scientific scuba diver course to as/nzs 2299.2:2002biophysics.sbg.ac.at/transcript/ssd.pdfscientific...

Scientific Scuba Diver Manual (AS/NZS 2299.2:2002) 1/123 Introduction

Scientific Scuba Diver Course To

AS/NZS 2299.2:2002

Manual compiled by Pierre Madl and Maricela Yip

Based on the lectures given by

Noel Teufel Boating & Diving Officer at the Centre of Marine Studies University of Queensland

Glen Halter Queensland Ambulance

Gary Chaplin Occupational Health and Safety Officer at the Centre of Marine Studies University of Queensland

Dr. Robert Long Hyperbaric Recompression Chamber at the Wesley Hospital Brisbane

Brad Hutcheson Acknowledgements for assisting during the practical Dive Lectures

Salzburg (AUT) / Brisbane (AUS), February 2003


The perfect SCUBA outfit


Table of Contents

Introduction ......................................................................................................................................................... 6 1. Scientific Scuba Diver (SSD) .......................................................................................................................... 7

Responsibilities and concepts of a SSD .......................................................................................................... 7 Diving at work ................................................................................................................................................ 7

2. Inspection and Execution of current Standards ............................................................................................... 9 Penalties .......................................................................................................................................................... 9

3. Risk, Risk Factors, Risk Control, and Risk Assessment for Diving.............................................................. 10 Risk Factors .................................................................................................................................................. 10 Risk Control .................................................................................................................................................. 11 Risk Assessment ........................................................................................................................................... 12 Dive Planing and Risk Assessment ............................................................................................................... 14 Simplified Risk Calculation .......................................................................................................................... 14 Detailed Risk Calculation - Record of RISK ASSESSMENT FOR UQ DIVING OPERATIONS .............. 15 Qualitative Risk Assessment tables ............................................................................................................... 16

4. Role and Function of a Scientific Scuba Diver (SSD) .................................................................................. 19 Research Diving Operation Log .................................................................................................................... 20 Responsibilities of the Team Supervisor during the course .......................................................................... 20

5. Diving Physics .............................................................................................................................................. 21 The Physical world ........................................................................................................................................ 21 Gases in Diving ............................................................................................................................................. 21 Measuring the Physical World and the SI-System ........................................................................................ 21 Density .......................................................................................................................................................... 22 Buoyancy ...................................................................................................................................................... 22 Pressure ......................................................................................................................................................... 23 Kinetic Theory of Gases................................................................................................................................ 23 Energy ........................................................................................................................................................... 25 Light .............................................................................................................................................................. 25 Sound ............................................................................................................................................................ 25 Heat ............................................................................................................................................................... 26 Propulsion, Drag, and Trim ........................................................................................................................... 26

6. Diving Physiology – Fitness, Respiration, and Circulation........................................................................... 27 Diving Fitness ............................................................................................................................................... 27 Respiration .................................................................................................................................................... 30 Ventilation ..................................................................................................................................................... 30 Lung Volumes and Capacities ...................................................................................................................... 31 Circulation ..................................................................................................................................................... 32 Effects of Immersion on Circulation ............................................................................................................. 33 Circulatory and general Physiological Problems .......................................................................................... 33 Breathing Problems ....................................................................................................................................... 36 Diving Maladies – Signs and Symptoms ...................................................................................................... 38

7. DeCompression Illness (DCI) / DeCompression Sickness (DCS) ................................................................ 40 Types of DCS: ............................................................................................................................................... 41 Symptoms of DCS ........................................................................................................................................ 41 Risk Factors favouring DCI / DCS ............................................................................................................... 42 Five Minute Neurological Exam ................................................................................................................... 42 Treatment of DCI and DCS: ......................................................................................................................... 43 Compressed Gas Treatment Record .............................................................................................................. 43

8. Decompression and Recompression .............................................................................................................. 44 Decompression Theories ............................................................................................................................... 44 Dive Tables ................................................................................................................................................... 45 Special Dive Table Procedures ..................................................................................................................... 46 Dive Computer Theory and Application ....................................................................................................... 48 Aids to Decompression ................................................................................................................................. 48

9. Rescue ........................................................................................................................................................... 49 The “Zero Accident” Goal ............................................................................................................................ 49 Pre-Emergency Signs .................................................................................................................................... 49 Stress - Chain of events ................................................................................................................................. 50 Dealing with “Out of Air” Situations ............................................................................................................ 50 Rescue and Rescue Techniques..................................................................................................................... 52 Underwater Rescue – Is it safe to intervene? ................................................................................................ 52


Surface Rescue .............................................................................................................................................. 53 In-Water Respiration ..................................................................................................................................... 54 Accident Management .................................................................................................................................. 56

10. First Aid and the Chain of Survival in Diving Accidents............................................................................ 57 Legal issues in 1st aid .................................................................................................................................... 57 The Chain of Survival ................................................................................................................................... 57 Risk of cross-infections ................................................................................................................................. 58 Victim assessment ......................................................................................................................................... 58 Resuscitation ................................................................................................................................................. 58 Breathing emergencies - Asthma .................................................................................................................. 61 Cardiac emergencies ..................................................................................................................................... 61 Shock and anaphylaxis .................................................................................................................................. 61 Soft tissue injuries, and Haemorrhages (Bleeding) ....................................................................................... 62 Chest injuries ................................................................................................................................................ 63 Dislocations, and fractures ............................................................................................................................ 63 Head and spinal injuries ................................................................................................................................ 64 Diabetes......................................................................................................................................................... 65 Eye injuries ................................................................................................................................................... 66 Epilepsy......................................................................................................................................................... 66 Stroke ............................................................................................................................................................ 66 Malaise and injuries predominantly related to SCUBA diving ..................................................................... 67 Cramps .......................................................................................................................................................... 67 Carotid sinus reflex ....................................................................................................................................... 67 Seasickness ................................................................................................................................................... 67 Disorientation and Vertigo ............................................................................................................................ 68 Dehydration ................................................................................................................................................... 68 Poisoning ....................................................................................................................................................... 68 Hypothermia ................................................................................................................................................. 71 Hyperthermia ................................................................................................................................................ 71 Venomous Bites and Stings .......................................................................................................................... 71 Burns ............................................................................................................................................................. 72

11. Oxygen Provider ......................................................................................................................................... 73 Why O2 .......................................................................................................................................................... 73 Handling O2................................................................................................................................................... 73 Administering O2 .......................................................................................................................................... 73 Practical Aspects ........................................................................................................................................... 74 Putting the System together .......................................................................................................................... 74 Demand Valve............................................................................................................................................... 75 Constant flow system .................................................................................................................................... 75 Recompression Therapy – The necessary 2nd Step ........................................................................................ 76 Hyperbaric Chambers ................................................................................................................................... 76

12. Diving Environment .................................................................................................................................... 78 Physical Aspects of water movement ............................................................................................................ 78 From Fetch to Waves .................................................................................................................................... 78 Surf ................................................................................................................................................................ 78 Tides .............................................................................................................................................................. 79 Currents and how to deal with them .............................................................................................................. 79 Thermal and salinity Changes ....................................................................................................................... 80 Weather Conditions ....................................................................................................................................... 80 Bottom Conditions ........................................................................................................................................ 80 Diving Environments (Fresh vs. Saltwater) .................................................................................................. 81 Biological Aspects (Aquatic Life)................................................................................................................. 81

13. Diving Equipment ....................................................................................................................................... 82 Scuba Systems............................................................................................................................................... 82 SCUBA Cylinders ......................................................................................................................................... 83 Cylinder Valves and Manifolds..................................................................................................................... 84 SCUBA Regulators ....................................................................................................................................... 84 Regulator Attachments: ................................................................................................................................. 86 Diving instruments ........................................................................................................................................ 86 Buoyancy Compensation Device (BCD) ...................................................................................................... 87 Dry Suits ....................................................................................................................................................... 87 Air Compressors ........................................................................................................................................... 88


14. Deeper Diving and Technical Diving Techniques ...................................................................................... 89 Diving Readiness .......................................................................................................................................... 89 Preparing to Dive .......................................................................................................................................... 89 Planning and Preparing for Successful Dives ............................................................................................... 89 Reducing Common Diving Risks .................................................................................................................. 90 Deep Diving (Planing & Execution) ............................................................................................................. 90 The Deep Dive .............................................................................................................................................. 91 Equipment Considerations ............................................................................................................................ 91 Environmental Hazards ................................................................................................................................. 92 Technical Diving ........................................................................................................................................... 93 Full-face-mask diving and u/w Voice Communication ................................................................................. 93

15. Navigation for Divers .................................................................................................................................. 94 Navigational Equipment for Divers .............................................................................................................. 94 Measuring Distance Underwater ................................................................................................................... 94 Means of Navigation ..................................................................................................................................... 94 Navigational Problems .................................................................................................................................. 95 Use of Charts ................................................................................................................................................. 95 Advanced Underwater Navigational Equipment ........................................................................................... 95

16. Limited Visibility and Night Diving ........................................................................................................... 96 What is Limited Visibility Diving? ............................................................................................................... 96 Factors Determining Water Visibility ........................................................................................................... 96 Techniques for Low Visibility Diving .......................................................................................................... 96 Night Diving and Equipment for Night Dives .............................................................................................. 98 The Night Dive.............................................................................................................................................. 98

17. Search and Light Salvage ............................................................................................................................ 99 Organization .................................................................................................................................................. 99 Risk Factors .................................................................................................................................................. 99 Search Patterns .............................................................................................................................................. 99 Light Salvage Procedures ............................................................................................................................ 101 Knots ........................................................................................................................................................... 101

Appendix ......................................................................................................................................................... 103 Diver Registration Form ............................................................................................................................. 103 Daily Diving and Boating Safety Record .................................................................................................... 104 Research Dive Operation Record Form ...................................................................................................... 105 Record of RISK ASSESSMENT form ........................................................................................................ 108 Scientific Divers Log Book ......................................................................................................................... 112 Rapid field Neuro Exam Record (1/1) ........................................................................................................ 114 Compressed Gas Treatment (1/1) ................................................................................................................ 115 Comments ................................................................................................................................................... 115 Information required when completing a workplace injury form (1/2) ....................................................... 116 Contact & Emergency Information ............................................................................................................. 117 Dive Medical Form (1/5) ............................................................................................................................ 118 Access to your personal information: .......................................................................................................... 122 References ................................................................................................................................................... 123


Introduction Your attendance at this course is highly valued. In accordance with our Mission Statement that identifies our desire to train students to World Best Standard Practices we request that you personally identify with a desire to participate and achieve the highest standard within your capability. It is this attitude that will develop you into a scientific diver and give you the satisfaction of a job well done. Whilst you strive for excellence it is well to remember that a good job is a job done safely and with this in mind we request that you read and observe the following guidelines. Course Objective: the course objective is to give comprehensive instruction in occupational / scientific diving to students with basic diving skills in order to prepare them for research / scientific in the research / scientific diving industry. This is not a course intended to substitute a dive course for beginners (e.g. open water diver), but rather builds upon the skills taught therein. Safety: at the University of Queensland, safety is of paramount importance, and must be considered as the primary consideration during each section of diver training. Students will be expected to make themselves aware of, The University of Queensland’s safety policy as soon as practicable, and abide by all safety rules and regulations set down by the Qld Workplace Health and Safety Act1. Safety rules are to be strictly observed where applicable, and any student who has any concern whatsoever should discuss the issue with the course instructor. Work boots are to be worn when handling cylinders or whilst within the University of Queensland confines. Safety equipment is to be worn or used in areas so designated or as requested by supervisory staff. Unauthorized modification of dive equipment is not permitted. Defective equipment should be reported to supervisory staff, appropriately tagged with a defect report and entered into the quality assurance system. Intoxication and/or personal dehabilitation from drug use is NOT tolerated. Whilst on course your body is working to high physical levels and your mind needs to be tuned to the job. Your safety depends on you being in control. At all times consider your fellow diving companions - although the most important person is you - the safety of those around you depends on your ability and concentration. It is expected that students will wear the relevant safety equipment where appropriate or when designated a “construction site” by the diving instructor. Log Books: students will be issued with a temporary log book. Full instruction will be given in the documentation of this book and will be examined as part of the final assessment. Log books are to be handed to the students supervisor at the end of the week for checking and signing by the course instructor. Housekeeping: all basic safety starts with good housekeeping, both on deck and in the quarters. Students are expected to police and tidy the area’s they use during the course. Body: the best equipment in the industry is only as good as the diver using it and likewise the total package is only as good as the training and discipline the diver has in the use of both. Personal hygiene, health and fitness are the top divers most important tools. You are not expected to graduate from the Scientific Scuba Diver course an expert. But as a SSD with a thorough knowledge of the basic skills required to be of value to yourself and your future employer. Then if you have the right attitude, after the process of gaining the necessary experience, you should become an asset to yourself and the scientific / research diving industry. Target Group: This course aims at students and researchers performing scientific work underwater. An open water ticket (PADI, SSI, NAUI, etc.) or equivalent is essential as the course does not cover basic underwater skills. Participants should be 18 years of age or over and have at least 20 hours of recreational diving experience.

1 http://www.uq.edu.au/ohs/

Scientific Scuba Diver Manual (AS/NZS 2299.2:2002) 7/123 Chapter 1

1. Scientific Scuba Diver (SSD) Purpose of this SSD course: • To increase practical and theoretical knowledge of scientific scuba diving. • To ensure that scientific scuba divers are suitable qualified and trained to dive supervisor standards. • To make scientific scuba divers aware of their responsibilities with reference to AS/NZS 2299.2:20022 and

Occupational Health and Safety requirements3. • Extra qualification of an SSD includes the following: • Oxygen Provider (see Chapter 11) • Radio Operator (see Marine Radio Operator Manual4) • Boating License for vessel greater than 12m (not yet available) • First Aid qualification (see Chapter 10) Responsibilities and concepts of a SSD The aim of this concept mainly focuses on the aspect of avoiding prosecution and to be aware of the risks involved in diving. Regulation is needed as many dive related incidents and accidents are mainly due to the lack of understanding and knowledge about diving in general and the risks involved. Regulations as those proposed under the AS2299 standards made it possible to reduce the number of dive related accidents to one fifth to those compared with the USA in the same period of time5. These regulations are set up by an independent body and an unbiased concept of the aims and goals (usually, recreational standards are made in a way to enable maximization of profitability, regardless of the fitness of applying candidates – a reason why certificates obtained from operators like PADI, SSI, etc. are not recognized by commercial dive industry). A SSD should remember that Decompression Incidents (DCI) are quite common especially in shallow water. Among other topics described in the manual (see also fig. 1.1) the cardinal responsibilities of a SSD are: • Be on Time • Bring your own equipment, as well as • Bring the tools required for the dive tasks Diving at work (in accordance with the Occupational Health and Safety Legislation - Application in the field): Under the current legislation, a SSD is considered as an employee of the University for which he performs the diving tasks. Unless the SSD is a level 3 diver (commercial license), it is essential to include outside contractors to perform the scientific task (e.g. underwater drilling activity for coral bore hole samples, for the operation of hydrostatic suction pumps, etc.), or even to include the help of other persons to get the underwater tasks properly done. Diving at the workplace may involve: • Designers, manufacturers, importers, and suppliers of plant. • Erectors and installers of a certain plant. • Manufacturers, importers and suppliers of substances required

underwater (fixation chemicals like formalin, etc.). • Owners of specified high-risk plants. • Workers and others

Fig. 1.1:General Boating, Diving, and

Snorkelling Information 6

2 https://committees.standards.com.au/COMMITTEES/SF-017/PRODUCTS/ 3 http://www.uq.edu.au/ohs/ 4 http://www.sbg.ac.at/ipk/avstudio/pierofun/funpage.htm


Such obligation is discharged by regulations or ministerial notice. It prescribes procedures and recommendations, following advisory standard equally to or better than; if none are applicable, reasonable precaution and diligence should be employed. Current mandatory regulation to which the Scientific Diving community is bound to: • Workplace Health and Safety Act (includes fines) • Workplace Health and Safety Regulation • Workplace Health and Safety Advisory Standards (set up by the ruling body of expert) • Industry Codes of Practice • Australian Standards • Other Standards of Information relative to the activity Applicable advisory standards do include a RISK ASSESSMENT (see Chapter 3), First Aid qualification, Directives of Manual tasks, as well as the impact of noise due to running compressors nearby. For example: the following sections of the Workplace Health and Safety Regulation state: • Section 52, 53, 54: Notification, Recording and Direction for Management ( every incident must be reported

to the supervisor or dive officer) • Section 76 to 78: Interpretations-, Construction Diving Work and ADAS (Australian Diver Association

Scheme); regard construction diving and is not of relevance for the SSD, as they usually lack level 3 classification.

• Section 78 to 79: Dive Medical according to AS 2299; includes all working divers like fish collectors, sea cucumber collectors, and other activities involving the recuperation of marine species via SCUBA equipment.

• Section 80: Qualifications according to ADAS • Section 81: Diver Supervisor • Section 83: RCC and ADAS qualified operator to be available • Section 84: Hyperbaric recompression chamber operated by ADAS qualified personal • Section 85: Restrictions to the use of self contained breathing apparatus (SCUBA) • Section 86: Restriction to the use of surface supplied breathing apparatus (SSBA) • Section 86A to 86J: involves the recreational diving industry (you pay someone taking you out for a dive).

Section 86A: Requirement to discharge Section 86B: Headcounts (prior to and after the dive trip, finalized with the signature of the diver); a safe procedure involves a double headcount (headcount, signature, headcount). Section 86C: Medical for Resort divers Section 86D: Lookout and Rescue staff both for boat and land-based operation Section 86E: Supervision of resort divers Section 86F: Dive safety logs

• Section 86G to 86J: involves the recreational snorkel industry. Section 86G: Requirement to discharge Section 86B: Headcounts (prior to and after the snorkel trip, finalized with the signature of the snorkeller); ); a safe procedure involves a double headcount (headcount, signature, headcount). Section 86C: Medical for snorkellers Section 86D: Lookout and Rescue staff both for boat and land-based operation Section 86E: Supervision of resort divers Section 86F: Dive safety logs

Compressed Air Recreational Diving and Recreational Snorkelling: The code provides further information to assist with the implementation of the sections of the regulation. Furthermore, information is provided about equipment that should be used, air purity, skills and knowledge issues, diver rescue and first aid, dive records, guidance notes regarding some maladies and general hazard area, i.e.: plant noise, hazardous substances involved with the dive, manual handling and work environment. Diving Skills - is used by all persons who dive whether they are construction, photographer, scientist, military, police or oilrig divers. In any case, skills should be so advanced that surface repetitions (a major cause of DCI) can be avoided at any time of the dive. Task Skills – or the work that they are doing to perform can be very specific to the goals of the employer although one would expect that a maritime archaeologist and oil rig diver using a “Broco” ultra-thermic cutter would be trained to the same level for the same type of work.

5 N. Teufel 17th of Feb. 2003, lecturing comment 6 http://www.geosp.uq.edu.au/11arspc/downloads/


2. Inspection and Execution of current Standards Currently three Health and Safety Inspectors operate along the Queensland coast, together with their associates, amount to about 100 inspectors enforcing these standards. Their powers to monitor and enforce current legislation include the following: • Search, inspect, measure, photograph (document) diving operations. • Take anything not in rule, and includes the copy(right) of documents. • Investigate workplace incidents (an incident is not an accident – in an incident nobody was harmed, e.g.

onboard equipment, or emergency gear is improperly maintained or even non functional). Tools of enforcement: Inspectors may impose notices (allowing time to fix it within a given period) or in severe cases may even lead to confiscation of items not in line or in severe cases even the entire vessel. • Improvement notices • Prohibition notices • Seizure of equipment. These measures are appealable, but come along with: • On the spot fines, • Court injunctions (court rulings), and • Prosecution Penalties Ignoring the warnings may bring about the exclusion from the project or may even induce penalties according to the regulations. Section 24 of the AS2299 standard lists the penalties (penalty units, PU = A$757): • Inducing a dive related Death or grievous bodily harm (GBH) quotes 2000 PUs or 2 years imprisonment. • Exposure to substances likely to cause GBH quotes 500 PUs or 1 year imprisonment. • For any other injury lighter than GBH quotes 400 or 6 months imprisonment. Any other breach of workplace Health and Safety Regulation that result in dive related incidents amounts to 30 PUs. On the spot fines can be issued when regulations for some regulatory breaches (e.g. failing to comply with improvement notices).

7 Currently one PU is the equivalent of A$75 and increases in line with the consumer price index (CPI)


3. Risk, Risk Factors, Risk Control, and Risk Asses sment for Diving Outlines the frequency of exposure to risk, ist probability of adverse outcome, and the seriousness of such an outcome. The following table illustrates an applicable model in the determination of the RISK factor (fig. 3.1): Procedure (although this procedure is quite subjective, it provides good approximation of the risks involved):

Probability: first the risk of failure of controls is determined and used as the starting point

Frequency: the corresponding frequency marks the slope

LINE: connecting these two and intersecting it with the center line generates the third reference point

Possible consequences: estimating the possible consequences yields the forth point which builds the second slope

Risk Slope: connecting the intersecting point of the center line with the forth point and extending it to the risk score line scores for the overall risk factor

Fig. 3.1: Risk score chart

Risk Factors Environmental conditions: certain parameters should be examined for their effects on the dive from the perspective of operations both on the surface and below, including, but not limited to –

(i) strength and direction of the surface wind and the degree of influence that it may have on the diving operation and emergency response capability;

(i) current and tide; (i) underwater visibility; (i) entrapment hazards (kelp forests, cords, nets, etc.); (i) depth at workplace; (i) water temperature (avoiding hypothermia / hyperthermia, a factor that determines the thickness of

the wetsuit); (i) time of day; (i) underwater terrain; (i) atmospheric temperature and humidity; (i) contaminants (working in oil tanks, septic tanks, sewage pipes, etc.) (i) isolation of the dive site (how long does it take to get a DCI victim to the next hyperbaric pressure

chamber); Task related factors also include the complexity of the diving task or the presence of a component, which is non-routine in nature and may increase the level of risk associated with a diving operation. Hyperbaric and physiological Risk Factors include:

(i) frequency of diving, including multiple ascents, repetitive diving, and multi-day diving; (i) depth and duration of dive; (i) breathing gas used (compressed air, Nitrox, Heliox, closed and semi-closed rebreather); (i) exertion required to reach dive site or to conduct task; (i) excessive noise (compressor noise, boat and / or container ship traffic, underwater drilling, etc.); (i) immediate pre-dive fitness (prior dives, prior physical exertion, fatigue, recent illness – big no-no’s

include alcohol consumption, narcotics, and nicotine); in order to reduce the risk of a DCI incident, drink plenty of water before and after the dive (600mL each time); and

(i) altitude exposure (dives exceeding 300m in altitude, in regards to the DCIEM table, must be treated with a correction factor);

The effects of associated activity factors should be assessed as well. Associated factors include: (i) manual handling; (i) boat handling; (i) dive platforms (pontoons, etc.)


Other hazards: presence of other hazards such as the following should be taken into account: (i) dangerous marine animals; (i) shipping movements; (i) water inlets (stay at least 100m away from a hydroelectric dam water inlet; the suction power of

such an inlet inevitable squeezes the diver against the grid, with no chance of detachment – unless turbines are shut down);

(i) use or presence of hazardous substances (chemicals etc), biological pollutants, or explosives; (i) other hazards peculiar to the dive location;

Emergency response factors: there should be an assessment of what would be required in case of an emergency. The assessment is treated extensively in Chapter 9. It must consider:

(i) the location and availability of appropriate emergency systems; and (i) emergency response procedures (what are the local phone or radio emergency numbers);

Risk Control Control of Risk is achieved by selecting from the hierarchy of control measures, one or more measures which individually or in combination achieve the required risk reduction. Appropriate control measures should be applied to risks, using the hierarchy of controls in the following order:

(a) Elimination – where the level of risk cannot be controlled to an acceptable level, no diving should take place;

(b) Substitution – where the risk can be controlled by performing the task using alternative methods of diving, consideration should be given to using these alternative methods (dry suit vs. wet suit, rebreather vs. SCUBA, etc.);

(c) Design – plant and procedure should be designed to minimize risk; (d) Isolation – persons should be isolated from the identified hazards.

Administrative controls – every dive plan should seek to minimize the degree and duration of the diver’s exposure to risk. Note: almost every aspect of dive planning falls into this administrative category. Other administrative controls include:

(i) training, supervision, experience, and selection of dive team members, including staffing levels;

(i) provision of an appropriate diving operations manual (see scan below);

(i) organization and planning before, during, and after the dive;

(i) selection of appropriate plant; and (i) selection of appropriate form and level of

communication.

Risk control involves also personal protective equipment: Appropriately designed and sized personal protective equipment should be provided, used and maintained. The limitations of all equipment used should be identified as part of the risk assessment process. Information from manufacturers and from records of prior dive experience should be used to identify limitations (fig. 3.2).

Fig. 3.2: Diving Safety Manual8

8 http://www.uq.edu.au/ohs/Divingweb.pdf


Risk Assessment A fun dive does have a different risk profile than a scientific dive where you work for someone else. Guidelines for recreational snorkelling include suitable sea condition, physical fitness proved by a medical statement, deployment of lookout staff on the boat, pontoon or shoreline (usually 1 lookouter per 10 snorkellers), avoidance of hyperventilation during activity.

With an SDD these guidelines are extended and include an assessment done by a competent person. It is the critical appraisal of a diving operation with particular emphasis on the potential risk to divers. The assessment process focuses on the overall risk to a diver from a number of elements rather than from the risk from one of these elements in isolation. Thorough assessment assists in the identification and prioritisation of the control measures to be applied. An assessment should be made on at least:

(a) the identification of hazards in the workplace; (b) the nature of the risks created by those hazards; (c) the degree of exposure to those risks; (d) the potential of those risks to cause injuries and illness; and (d) the measures required to control the exposure to those risks.

A risk assessment has the objective of prevention of death, injury or illness being caused by a workplace, workplace activity or specified high risk plant. It is achieved by preventing or minimizing exposure to risk of death, injury, or illness caused by dive related work; i.e. knowing the working environment.

• Site location • Dive profiles • Abiotic factors (temperature, freshwater vs. saltwater, etc.)

Examples of a dive related Risk: Tagging reef sharks: White tip reef sharks (species name) are able to bend their torso by 180°, while black tip reef sharks (species name) do not have this flexibility. Therefore, holding a white tip on its caudal fin will end up in serious bite injuries. Working with cone shells: working with live molluscs especially those of the genus Conus may inflict serious injury. Great care is needed when handling a conus as its proboscis can quickly become very long. C.geographus is among the most dangerous. Control Measures: • Eliminate the hazard (equivalent to no diving) • Substitute (e.g. exchanging the compressed air supply with a mixed gas, nitrox, or rebreather system) • Redesign task that should be done underwater to make it safer • Isolate • Administrative controls (lookouts, emergency O2 kit, supervisor onboard, etc.) • Personal protective equipment (e.g. dive knife, electromagnetic shark repellent, etc.) Sources of information available: • Workplace Health and Safety Regulation9 • Advisory Standards • AS/NZS 2299.1, 2, & 3 AS 2815 series (training standards)10 • AS 3848.1 • Training Agency materiel as it relates to their professional streams • Occupational Diving texts • Diving medical text and journals

9 http://www.uq.edu.au/ohs/pol-ae.html 10 https://committees.standards.com.au/COMMITTEES/SF-017/PRODUCTS/


Scenario: The following is an example that should illustrate the range of applications in the field of Workplace Health and Safety Legislation; UQ has agreed to undertake a dive operation for a government department; this involves collection of samples of species from the channel to St. Lucia Campus including Luggage Point, Cairns Cross, Hamilton Wharf, Qld Police Wharf, and Riverside Centre. It will also require lifting of structures in which molluscs are attached (fig. 3.3).

Pre dive planning: • Isolation • Site features approach details. • Personnel: Qualification and experience,

medical status (includes that one of the buddy).

• Equipment requirements and equipment maintenance status (includes own SCUBA gear, that should have been checked within the last 12 months along with documentation as proof).

• Communications (e.g. full faced voice com., untethered dive, sonic beacon, etc.).

• Emergency procedures (emergency numbers for hyperbaric treatment facilities, DAN contact numbers, evacuation facilities and procedures, etc).

• Conditions under which operations likely to occur.

• Standard operating procedures. • Things likely to effect the operation. • Authorities required (permits, etc.) On Site Emergency procedures: • Assistance to divers underwater • Recognition of emergency • Activation of search and recovery • Recall • First Aid (O2-kit, must be operational

before dive commences) • Evacuation • Communication Pre dive planning on site: • Site conditions • Medical status of dive team • Supervision • Status of equipment • Establish communications • Emergency procedures (dive sausages,

glow sticks, whistle, pony dive lamp, pony gas tank with regulator, etc.)

• Monitoring process • Planning profiles • Assign tasks (who is doing what) Dive Profile Planning: • Depth • Time • Endurance, SCR (calculate surface

consumption rate)

• Conditions • Human Factors • Tasks • Decompression obligations (using the

DCIEM tables) • Breathing gas tank pressure Dive execution (supervision): • Monitoring • Assessing • Recording • Communication Post dive: • Monitoring of events • Equipment status • Breathing gas usage (check and monitor

pressure and depth gauges) • Decontamination (Sewage outlet at

Luggage point) • Gather relevant information –

reassessment • Recording of information Failure Analysis: • Isolate equipment / site • Obtain information • Record • Report • Assess hazard and risk (essential for

follow-up investigations at same site) • Formulate changes • Adjust dive operation Record File

Fig. 3.3: Research Diving Workplan11

11 see Appendix for complete form


Dive Planing and Risk Assessment Before commencing any dive activity, the preparative work must include the planning of the dive, assessment of risks, and any paper work connected to that activity. In particular, the dive must be registered with the Dive Officer and / or the agency acting as the employer. Planning the Dive: Hazards should be identified at the time of registration of the dive site, during the preparation of the dive plan and at the dive site prior to the commencement of the dive. Any hazards, which arise during the dive, should immediately brought to the attention of the dive coordinator and the dive plan varied as necessary to ensure the health and safety of the diver or the dive aborted. Risk factors that must be already included prior to the dive; e.g. dive site is known to house oyster banks that represent an increased risk of getting cut when exposed to strong currents.

Fig. 3.4: Diver Registration form to enter the divers personal data

into the database 12

Fig. 3.5: Diver Safety

form required to register for any dive activity13

The assessments process should be undertaken in consultation with divers in the following three parts: (a) Dive Site Registration – in assessing the risks posed

by working at a particular site at the beginning of a scientific program (fig. 3.4).

(b) Before the diving operation commences, the selection of appropriate control measures for inclusion in the dive plan must be established.

(c) At the dive site and during the diving operation – ensure that the limitations of the control measures selected are not exceeded, including during the dive and post-dive activities.

The safety form must be filed every single time a dive will take place, and must be submitted to the Dive Officer for registration (fig. 3.5). Remember: know the local emergency numbers and the location and phone number of the nearest working hyperbaric treatment facility for each of the dive sites before you dive! Simplified Risk Calculation The following part of this chapter provides a detailed analysis and evaluation of the risks involved in dive related working activities: in essence the evaluated risk should be in the green range. Where the risk is: Very high / High - work should not

continue until improved controls are in place

Medium / Low - improved controls must be provided as a high priority

Very low / Negligible - risk is “not significant”

Severity of consequence Likelihood of injury

Fatality Permanent

injury Hospital in-patient

Medical treatment

First Aid only

Frequent Very high Very high High Medium Low Occasional Very high High Medium Low Low

Rare High Medium Low Low Very low

Improbable Medium Low Low Very low Negligible

12 http://www.marine.uq.edu.au/divreg.html 13 http://www.marine.uq.edu.au/safety.html


Detailed Risk Calculation - Record of RISK ASSESSMENT FOR UQ DIVING OPERATIONS DIVING TASK RISK ASSESSMENT & CONTROL - Conduction an Appropriate Assessment (fig. 3.5) Overview: on commencement of any UQ Diving Task, or prior to departure for any university diving trip not

covered by a previous risk assessment, the DIVE Coordinator for the trip must ensure that a completed risk assessment for the trip is provided to the University Boating and Diving Officer or the Site Diving Officer HIRS / LIRS. Where a risk exists for any project or task, it is the responsibility of the Dive Coordinator to review this on a regular basis and update it when any of the Diving Task conditions or procedures alter in any substantial way - such that an increased risk may exist.

Scope: this procedure describes how the risks involved with particular planned activities are assessed and how controls for theses risks are selected. The Dive Coordinator / Leader should address both project and task risks, and specific hazards where these are deemed medium to high risk for any project.

Definitions of crucial terms: Responsible Person: an individual who assumes responsibility for the health or welfare of any other person in a workplace by providing instruction, direction, assistance, advice, or service, is deemed a Responsible Person in accordance with the Workplace Health and Safety Regulations 1995 and related legislation14. All management and supervisory staff (incl. those with responsibility to students) are therefore considered Responsible Persons. Employee: for the purpose here, employee refers to any staff member, student, visitor, or volunteer. Hazard: a situation , activity, or task with the potential to cause injury or damage. Responsible Officer: Deans, Heads of Division, Heads of School and Administrative Sections have been designated Responsible Officers under the Workplace Health and Safety Act 1995 and related legislation. Risk: a situation, activity, or task with some actual likelihood of harm or damage.

Responsible Person: the Dive Coordinator for a planned diving project or task is responsible for ensuring an appropriate risk assessment is performed and approved and at appropriate risk controls are in place prior to commencement of work.

Procedure: as mentioned above, the planned project or task should be assessed by the person in overall charge of supervising the project / task in the field. This would normally be the Dive Coordinator. As a minimum (if the assessment has been prepared by another employee), the assessment must be reviewed and signed by the Dive Coordinator and the Project Leader (where these differ), before being forwarded to the University Boating and Diving Officer or Site Diving Officer HIRS / LIRS. The Coordinator or delegated team member shall perform a risk assessment (as described below) for each activity, and document their findings on the Diving Risk Assessment form. This can be done by adopting the following measures:

1. fill out the 1st page of the Diving Risk Assessment form, listing date of assessment, date / times of work, type of work being undertaken, where work is being carried out, name of person conduction assessment and those participating in the work.

2. List any additional identified hazards (refer to Hazard Check list - Diving) in the 1st column of each of the conditions 7 hazards section of the form (environmental, task related, hyperbaric / physiological, associated activities, others, and emergency response).

3. In column 2 of the Diving Risk Assessment form, assess consequences applicable to the specific task or activity (see table 2, Assessment of Consequences or Impact).

4. For each potential hazard identified, assess and record the likelihood (see tables 1, Qualitative Measures of Likelihood). NB: a specific hazardous substance risk assessment form may assist in the documentation of hazards associated with the handling, use or production of a hazardous substance.

5. Then find and record the potential risk to people in column 4 (see table 3, Level of Risk). 6. In column 6 of the Diving Risk Assessment form specify the risk control measures required to ensure all

identified hazards are controlled. In specifying control measures, the hierarchy of controls listed below should be considered - in priority order (see table 4, Risk Score).

7. Once these risk control measures have been applied reassess risk and record this in column 6.

8. Using table 4 Risk Score, determines if diving should commence / continue. Diving operations should only commence or continue when the risk score is either L or CR. Should the risk score change during diving operations then actions should be taken to reduce the risk to L or CR.

9. All workers must read and understand the risk assessment before signing the assessment.

Fig. 3.5: Risk Assessment Form15

14 WHSR act: http://www.marine.uq.edu.au/???htm 15 See Appendix


Proof should be able to be provided that a higher order level of control is not practicable. A risk assessment must be reviewed at any time when information indicates that it is no longer valid, but at least at intervals not exceeding 2 years. As mentioned previously, determining the need for any review of a Risk Assessments is the responsibility of the Dive Coordinator / Field Supervisor for a given project.

Records: copies of completed Diving Task Risk Assessments shall be retained by the University Boating & diving Officer or Site Diving Officer HIRS / LIRS, and it is the responsibility of the field supervisor who completed the assessment to ensure that copies are made available to all employees undertaking the assessed tasks, or involved in the project.

The Diving Risk Assessment form and Hazard list provided in this document should be used together, to assist in evaluating the level of risk involved in any diving operation. Qualitative Risk Assessment tables Table 1: Qualitative Measures of Likelihood Table 2: Assessment of Consequences or Impact Level (Descriptor) Description Level (Descriptor) Example of description

A (Almost certain) The event is expected to occur in most circumstances.

1 (Major)

Extensive or life threatening injuries, emergency protocols enacted, loss of production capability, emergency services required.

B (Likely) The event will probably occur in most circumstances.

2 (Moderate)

Medical treatment required, emergency services required, person is not able to continue work.

C (Possible) The event should occur at some time.

3 (Minor) 1st aid required, person may / may not be able to continue work.

D (Unlikely) The event could occur at some time.

4 (Insignificant) No injuries, person able to continue work.

E (Rare) The event may occur only in exceptional circumstances

Table 3: Qualitative Risk Analysis – Level of Risk Likelihood Severity of Consequences 1 (Major) 2 (Moderate) 3 (Minor) 4 (Insignificant) A (almost certain) E E H H B (likely) E H H M C (moderate) E H M L D (unlikely) H M L L E (rare) H M L L

Table 4: Risk Score Symbol Risk Pre-dive During Dive

E Almost certain Dive must not commence Urgent action required H High Risk Dive must not commence Action required at earliest possible

moment M Moderate Risk Dive must not commence unless routine

management practices are in place and have been evaluated

Action required

L Low Risk Dive can commence with routine management practices in place

Continue managing with routine practices

CR Controlled Risk Diving may commence with controls in place

Diving may commence with new controls in place

Note: diving operations should only commence or continue when the risk is either L or CR. Should the risk score change during diving operations then actions above should be taken to reduce risk to L or CR.


Table 5: Types of Control - Use in order of severity Type of control Description Elimination Remove hazard. If not possible, or where another control cannot be implemented which

substantially reduces the risk, no diving will take place. Substitution Use an alternative method of work. Engineering / design

Ensure that plant and procedures are set up to minimize a risk; e.g. separate divers from a hazard.

Administrative / training

Ensure administrative processes are in place to minimize risk where applicable; e.g. field reporting procedures. All divers must be trained in work procedures offering greatest safety.

Protection Ensure that personal protective equipment is more than adequate for its intended purpose; e.g. wetsuits are of adequate thickness for task / temperature, or drysuits are worn.

Table 6: Examples of Control

Hazard Type of control Description Cold water Substitution Replace wetsuit for drysuit, thicker wetsuits or hot water suits. Barotrauma Administrative /

training Ensure divers are adequately trained and experienced, and to cope with foreseeable emergency situations.

Blue-green algae

Design Separate diver from the hazard using a drysuit and a lock on the helmet. Use decontamination procedures.

Current / tide Elimination / design

Dive only at slack water if tidal current. Use adequate harness and lifeline in all cases. Buoy dives if free swimming, and work vessel “live”.

CO poisoning Elimination Ensure that plant is set up in such a way that CO poisoning risk is removed; e.g. use SCUBA instead of SSBA compressor supplied air.

Table 7: Diving Risk Table (the following checklist of hazards / risks and other items may be of assistance when

planning diving work): RISK FACTOR LOW RISK MODERATE RISK HIGH RISK

Weather and sea Calm, settled weather pattern

Calm, unsettled weather pattern

rough

Site exposure Sheltered Exposed

Time of day Start and finish in full daylight

Start at / before dawn and finish near / after dusk

Night diving

Current at site Nil to weak Moderate Strong Depth at worksite <18m 18m – 30m >30m

Site location Location not remote, sheltered embayment with uniform bottom profile

Exposed site and remote location

Number of personnel 2 –3 divers (multiples) & 1 boat handler per team

2 – 3 divers (multiples) and no boat handler

Single diver

Diving experience of personnel

>50hrs 50hrs – 20hrs <20hrs

Duration of dive At least 2 repetitive groups less than deco-limit

1 repetitive group less than no-deco limit

Dive to no-deco limit

Dive profile “ideal” profile “square” profile “reverse” profile or, “sawtooth” profile

Multiple ascents None One or two Three or more

Local knowledge Know site well Some experience with or knowledge of site

Little knowledge of site

Affect of boat traffic on dive site

Infrequent traffic; depth >5m

Some traffic depth or <5m SSBA dive

High traffic / shipping lane, depth <5m SSBA dive

Entrapment hazards Unobstructed ascent Obstructed ascent Medical assistance <30min away 0.5hrs – 2hrs away >2hrs away Repetitive diving No more than 2 per day 3 – 5 dives per day >5 dives per day Time since last dive <3months 3 – 6months >6months

Handling marine life General observation Observation of dangerous animals

Spearfishing / manipulation of dangerous / venomous animals

Task related risks Use of slates & cameras Use of handheld pneumatic tools and / or small liftbags

Use of heavy tools / frames and / or large lift bags


Table 8: Hazard Checklist in Diving (the following checklist of hazards and other items should be considered when planning diving work)

Task related factors - free-swimming survey work - quadrat survey work - transect survey work - lifting with liftbags - suction sampling with air lift - sample collection - enclosed diving (caving / wreck) - hydraulic / pneumatic tools - explosive tools - cutting or welding - photography (cold) - boat handling / unguarded

propellers - shipping movement - manual handling - pressure differentials / suction - entrapment - entry / exit methods - lifeline entanglement - dive profiles - sufficient trained personnel Fauna & Flora - stinging animals (marine) - other dangerous marine animals - handling of small animals - handling of large animals 1st Aid requirements - 1st aider in group - 1st aid kit in tow vehicle - 1st aid kit in boat - O2 cylinder (adequate size) - any additional items required? Pre- / post dive clothing - sun hat - towel - winter clothing (all year) - trousers / overalls - wet weather equipment - appropriate footwear Pre- & post-dive factors - pre dive fitness - fatigue - dehydration - drugs / alcohol - exercise - sleep deprivation Dive team - size - composition - experience of each individual - fitness - individual medical conditions

Personal protection - adequate exposure protection (e.g.

exp. Suit, gloves, boots, hood) - harness (SSBA / tethered SCUBA) - over-gloves - lycra suit - overalls over wetsuit / drysuit - welding visor - adequate clothing f. dive attendant Personal - sunburn - heat stress - cold stress - manual handling, lifting - striking and grasping - slips and trips - mental stress - personal security and safety - individual medical conditions Transport - tow vehicles and vessels - aircraft - fuel requirements - launch and retrieval of vessel - tow vehicle size / capability - vessel size - vessel engine size - safety equipment aboard - secure from theft - radio and operator present - diver / cox’n licensing - flying after diving - sea conditions on way to site Underwater Navigation - training - diver experience - direction determination - visibility Communication - between participants - with locals - with nominated contact - training and experience - equipment types available - underwater radio communication - lifeline communication - familiarity with standard signals Tides and Weather - general - tide data - met. bureau forecast - radio broadcasts

Essential site information - wind and sea state - current / tide at or on way to site - air and water temperatures - time of day - maximum depth of site - maximum depth of dive/s - contaminants / biological hazards - entrapment hazards - underwater terrain - isolation - remote sites - floating hazards - sun / ice Fire Risk - extinguisher in vessel - combustibles on vessel Emergency Response Factors - location / availability of emergency medical system

- emergency response / evactn. plan - trapped / lost diver - communications Hyperbaric / Physiol. Factors - barotraumas of ascent / descent - decompression illness - hypothermia - hyperthermia - CO poisoning - CO2 poisoning - N2 narcosis - O2 toxicity - drowning - exhaustion - cross infection Fire and Explosion - flammable substances - explosives Thermal hazards - cryogenic fluids - hypothermia - heatstroke Electrical - high voltage equipment (e.g. generator)

- 240V electrical equipment Overseas fieldwork - disease - vaccinations - political climate Other (specify)

For the Diving Risk Assessment forms see Appendix


4. Role and Function of a Scientific Scuba Diver (S SD) Scientific Diving is performed for the purpose of professional scientific research, natural resource management or scientific research as an educational activity. There are many categories of scientific scuba divers and their roles and functions vary accordingly. Categories include: • Restricted Scientific Diver: Persons who are involved in research requiring diving but who have limited

diving experience and are deemed by the diving officer of their host institution not to have experience equivalent to a scientific diver. They shall:

i) be 18 years of age. i) Not dive using SSBA (surface supplied breathing apparatus for hostile environments) equipment. i) only dive when conditions are suitable for untethered SCUBA mode (attached to a line for enhanced communication and emergency procedures – see Chapter 16 Limited visibility and Night Diving). i) Not dive deeper than 18 meters depth. i) Not act as a standby diver or a dive leader. i) Not dive as a restricted diver other than for a single initial period of up to 12 months. i) Not use powered underwater tools or lift bags.

Role: a diver that is involved in research, natural resource management or educational diving under the direct supervision of an unrestricted scientific diver, dive leader, dive coordinator, and / or dive officer. Function: to ensure that they are familiar with, and dive in accordance with the pre- dive plan. Act as a buddy diver during the dive to others in their group and maintain effective two-way communications with each other at all times.

• Unrestricted Scientific Diver: usually the researcher involved in diving activity. Role: a diver that is involved in research, natural resource management or educational diving under the direct supervision of a dive leader, dive coordinator, and / or dive officer. Function: to ensure that they are familiar with, and dive in accordance with the pre- dive plan. Act as a buddy diver during the dive to others in their group and maintain effective two-way communications with each other at all times.

• Dive Leader: usually the researcher involved in diving activity. Role: a person in charge of a specific part of a diving operation. Function: when in charge of a single group of divers, a dive leader takes responsibility for any decision required as the dive proceeds (in consultation with the dive coordinator). This person also ensures that other buddy diver(s) in the group are familiar with, and dive in accordance with the pre- dive plan. Furthermore, the Dive leader conducts the dive in accordance with AS/NZS 2299.2:2002 and local Occupational Health and Safety Regulations.

• Dive Coordinator: usually the researcher involved in diving activity. In order to fulfil the role of SCUBA Dive Coordinator, a person shall:

i) be an unrestricted SSD. i) be able to recognize and manage diving emergencies. i) have at least 15 hours of experiences as a SSD. i) satisfy any other reasonable requirements specified by the organization’s diving officer.

Role: a person who supervises and coordinates any SCUBA dive and is responsible for dive team safety. Function: to ensure that all scientific SCUBA diving operations under supervision are carried out in accordance with AS/NZS 2299.2:2002 and local Occupational Health and Safety Regulations.

• Diving Officer : usually a person who is not involved in research activity but permanently occupied with the safety of diving procedures, equipment and vessels needed in diving operations. In order to fulfil the role of Diving Officer, a person shall:

i) be trained to a level equal to or exceeding that specified in AS 2815.1. i) have at least 100 hours of underwater diving experience. i) satisfies any other reasonable requirements specified by the organization. i) keep up to date with current developments in diving technology and practice.

Role: a person who has been nominated in writing by the employer and who is ultimately responsible for all diving activity. Function: to be familiar with any legislation or guidelines, particularly AS/NZS 2299.2:2002, Occupational Health and Safety Requirements and Employers Safety Manual. The Dive Officer ensures that diving operations are safe – and to restrict or prohibit any that are considered unsafe. The Dive Officer also has the duty to update procedures, practices and / or equipment in a timely manner. Diving Officer at UQ, Moreton Bay Research Station, Heron Island Research Station, Lizard Island Research Station: Noel Teufel. Site Diving Officer at Heron Island Research Station: Jim Lawrence.


Research Diving Operation Log Details of every dive for each diver must be recorded on this form DURING THE DIVE by the surface Dive Attendant. At the end of a trip, the form must be signed off by the Dive Coordinator, and submitted to the University Diving Officer before another dive is permitted. Where more than one dive is done by a diver on a trip, please record the dives sequentially on this form (fig. 4.1). In addition, the SSD is required to enter all dive specific data into her / his own logbook. The entered data is then verified and signed by the Dive Coordinator, and kept with the SDD for personal reference. When taking up a position with another governmental body or educational institution, this logbook is of crucial importance as it will be the only document to proof the amount and type of diving activity performed as a SDD.

Fig. 4.1: Research Dive Operation Record16

Responsibilities of the Team Supervisor during the course The team supervisor is responsible (under the guidance of the course instructor) for all the daily operational activities, security, and quality assurance during the course of each day, and the duty week. Each student shall be required to carry out the duties of the team supervisor for one day during the course, and will be assessed as part of the competency based assessment on the proficiency of carrying out these duties. The following is a brief outline of the duties: 1. organizing and preparing of all equipment necessary

for the days program. 2. to plan and organize each team member into tasks

for the day; e.g. check compressor, safety equipment, dress diver, etc.

Fig. 4.2: SSD Logbook17

3. to ensure that at the end of each diving day an inventory of all diving equipment used is completed and equipment returned to a secure place.

4. to ensure that at the end of each day any defective equipment is appropriately tagged with a defect report and entered into the quality assurance system correctly.

5. to ensure by use of a checklist, that all equipment, fuels, etc., necessary are loaded onto the transport prior to going to the work site.

6. to ensure that at the end of each day all dive log books are filled out correctly, any dive sheets are filled out correctly, with enough detail, are signed by the diver, and supervisor, then returned to the course instructor, for endorsement and filing into the students file (fig. 4.2).

7. to ensure that at the end of the week, all divers logbooks, stores inventory, and equipment defect reports are correctly completed and left on the course instructors desk for checking, endorsement, and filing in the students files.

8. to ensure that at the end of each day, all equipment is washed, maintained, and is stored in the designated location.

9. to ensure that at the end of each day, the lecture room and work areas are cleaned and maintained in a clean, tidy, safe, and operable condition.

10. to ensure that all rubbish is to be placed in refuse bins which should be emptied daily. 11. to ensure that at the end of each day, all empty or low on air SCUBA tanks are charged to their relevant working pressure, and returned to secure storage. Remember: the student is not a one person band and during the day as team supervisor (s)he will be assessed for leadership and people management.

16 see appendix (UQ Research Dive Operation Record Form) 17 see Appendix (SSD Log Book)


5. Diving Physics The Physical world Matter is composed of atoms, itself considered the smallest unit into which it can be divided and still retain its unique character. Each element is comprised of only one kind of atom, giving it distinctive characteristics; e.g. carbon (C), oxygen (O), hydrogen (H), etc. Molecules are groups of atoms bonded together. A molecule is the smallest identifiable unit into which a substance can be divided and still retain its composition and chemical properties.

Fig. 5.1: The three states of matter

The three fundamental states of matter are solid, liquid, and gas (fig. 5.1). In a solid, the atoms are relatively ordered and structured, thus giving it a definite shape and volume. In a liquid, the molecules “flow”, allowing it to take the shape of its container. A gas, has neither a definite volume nor a definite shape as it will expand to fill any closed container - such as a SCUBA cylinder. Gases in Diving Air is the gas most familiar to us. Being a mixture it is primarily composed of nitrogen (N2), oxygen (O2), Argon (Ar), Carbon Dioxide (CO2), and traces of some rare gases. Some gases such as water vapour (H2O) and CO2, are present in varying concentrations depending on place and time (fig. 5.2). In diving, these gases can become toxic; this is covered in chapter 10 1st Aid & Chain of Survival. Nitrogen (N2): it is a colourless, odourless, tasteless gas and is the most plentiful component of air. For humans, N2 is a metabolically inert gas when inhaled, instead, humans have to rely on food to cover the nutritional demand of N-compounds.

Fig. 5.2: The composition of air rare gases 0.003% (CO, H2O)

Although N2 is of no need, breathing it at increased pressures implicates potential dangers that range from N2 narcosis to DCS (see chapter 7, DCI/DCS). Oxygen (O2): likewise a colourless, odourless, and tasteless gas, it is metabolised in the cells of the body to generate energy and heat. O2 itself does not burn, but supports combustion. Breathing higher partial pressures of O2 can lead to O2 toxicity, including convulsion and loss of consciousness. Carbon Dioxide (CO2): it is a colourless, and in low concentrations, odourless as well as tasteless gas that reacts readily with H2O to form carbonic acid (H2CO3). CO2 is the by-product of our metabolism and expelled via the lungs during exhalation. The level of CO2 in our body is monitored by specialized cells, which regulate the stimulus to breathe. Carbon Monoxide (CO): is likewise a colourless, odourless, and tasteless gas, but highly poisonous, as it has a 200 times greater affinity with the red blood cell’s haemoglobin. Thus CO-intoxication prevents O2 take-up and will ultimately lead to cell death if CO levels increase beyond tolerable levels. Water vapour (H2O): the amount of water vapour in the atmosphere is referred to as humidity and usually expressed as relative humidity (percent to which air is saturated with H2O-vapor at a given temperature). As air is cooled, its relative humidity will rise as the total amount of H2O the air is able to contain it decreases. If cooling continues below saturation temperature (dew point), moisture will condense. Measuring the Physical World and the SI-System Length: a meter [m] is defined as the distance light travels through a vacuum in 299.792458⋅E-6 seconds. Area: the SI metric system use units of length squared to measure area in units of meters squared [m2]. Volume: is the measure of space occupied, and capacity is the measure of volume that can be contained. Both are expressed in units of length cubed (length x width x height) in units of meters cubed [m3]. Weight (mass): the standard unit of mass is the kilogram [kg] or 1000g. The kilogram is approximately equal to the mass of 1 L of pure water at 4°C. Temperature: it is the measure of hotness or coldness. Heat and temperature are related, but they are not the same. Heat is a form of energy, and temperature is a measure of the amount of heat energy present. In the SI system, temperature is given in [°C] or [K]. The Kelvin scale refers to absolute zero (-273.15°C). Conversion from Celsius to Kelvin: T[K] = T[°C] + 273.15


Density It is the mass per unit volume; the density of dry air is 1.293kg/m3 and changes with increased levels of humidity. The density of seawater (1.025kg/L, slightly denser than freshwater – fig. 5.3.) chances with its salinity, this in return directly affects the buoyancy of the diver.

Fig. 5.3: Max. density of freshwater is reached at

3.98°C; increasing density by adding salt increases buoyancy (inlet)

Fig. 5.4: Hydratation of ions in seawater

ρ = m V

m, mass V, volume

[g] [m3]

Density is often observed in two phenomena known as a thermocline (a zone of rapidly changing temperature) and a halocline (a similar layering of waters of differing salinity in which lighter fresh water floats on top of denser salt water). These two phenomena are more explicitly explained in the chapter 12 (Diving Environment) Oceanographers measure salt content of ocean water in grams/kilogram of seawater [g/kg] or parts / thousand [%0]. The total quantity of dissolved salt in seawater is known as salinity. Six ions make up more than 90% of the salts dissolved in seawater: Na+, Mg++, Ca++, K+, Cl-, and SO4

=. NaCl ions together account for 86% of the salt ions present in seawater. Anions and cations are enveloped due to the polar properties of water. Under NTP conditions, the hydratation envelope keeps the oppositely charged ions separated from each other (fig.5.4). Buoyancy Archimedes noted that an object wholly or partially immersed in a fluid is buoyed up by the force equal to the weight of water displaced; i.e. any object that has the same density as the water will neither float nor sink, but remain wherever it is placed in the water column (fig.5.5). The buoyant force depends on density of the fluid in which the diver is immersed. Ocean water is about 2.5% denser than fresh water; therefore, a diver would have to add more weight when changing from fresh water to salt water to compensate for increased buoyancy. Not doing so would make the diver positively buoyant (drifting upward), while leaving extra weight on when going back to fresh water would make the diver negatively buoyant (sink).

Fig. 5.5: Archimede’s Principle: the displaced amount

of water corresponds to the weight of the immersed body

The ideal weighting of a diver (without weights) but with full gear and tank should be such that the person only sinks to the level of the chin (after a fully inhaled breath) while sinking to the forehead level (with a fully exhaled breath). In this state the diver is said to be neutrally buoyant.


Pressure When humans descend beneath the sea, the pressure around them increases tremendously. To keep the lungs from collapsing, air must be supplied also under high pressure. This exposes the blood in the lungs to extremely high alveolar pressure (hyperbarism). A tennis ball left in the pocket of the BCD will compress easily at 17m depth and deflate suddenly when ascending back to the surface - leaves a “nice” bruise! Physically speaking, pressure (p) is the force acting on a Unit Area (fig.5.7) usually given in [Pa] or [N/m2]:

Fig. 5.6: The buoyant force on a cube is the difference

between the downward force on its top face and the larger upward force on its bottom face.

Fig. 5.7: Pressure is not only determined by weight but

also by the area it acts upon

p = F A

= m⋅g A

F, force m, mass A, area

[N] [g] [m2]

p= ρH2O⋅g⋅A⋅d ρH2O, density

g, grav. const. 9.81 d, depth

[g/m3] [m/s2] [m]

Divers experience pressure as the result of the weight (not mass) of the air (atmospheric pressure), plus the weight of the surrounding water (hydrostatic pressure). Ordinary pressure gauges show the pressure in absence of atmospheric pressure. This is called the relative (or gauge) pressure and is to be distinguished from the absolute pressure. The absolute pressure is defined as the pressure that takes into account the atmospheric pressure plus the pressure exceeding it. A 10m column of seawater exerts the same pressure at its bottom as the entire atmosphere above the earth. Therefore, a person at 10m beneath the ocean surface is exposed to a pressure of 2 atmospheres, 1 bar caused by the air above the water and the other bar by the weight of the water itself; e.g. a relative cylinder pressure of 0bar indicates that it has the same pressure of the surrounding atmospheric pressure, i.e. one atmosphere equivalent to 10msw of absolute pressure.

1atm = 1.013bar = 760mmHg = 101.3kPa = 1103N/m2 = 1.033kg/cm2 = 1033g/cm2 = 10.08msw (meters seawater) = 10.67mfw (meters fresh water)

Kinetic Theory of Gases The ideal gas law describes the interrelation of pressure, volume, and temperature. It describes the dynamics of a perfect or ideal gas.

Fig. 5.8: Lift bag underwater: volume vs. pressure

p⋅V = n⋅R⋅T

p, pressure V, volume

n, molar amount R, gas const. 82.1⋅E-3

T, temperature

[atm] [L] [mol] [L ⋅atm/(K⋅mol)] [K]

Boyle’s law: for any gas at constant temperature, the volume of the gas is inversely proportional to the absolute pressure:

p1⋅V1 = p2⋅V2 The image on the right shows a lift-bag at sea level containing 1L of air. At 10m beneath the sea (2bar), the volume has been compressed to only ½ and at 8bar (71m) to 1.25L. Thus the volume is inversely proportional to the pressure (fig. 5.8). Boyle’s law is extremely important in diving because increases in pressure can collapse air chambers of the diver’s body; e.g. squeezes, equalization of air spaces, reverse blocks, and lung rupture injuries are all examples of this law in action. This law can be illustrated using cylinder capacities (as shown in the calculation of the Surface Consumption Rate (SCR) in the following section.


Charles’ law: for any gas at a constant pressure, the volume of the gas is directly proportional to its absolute temperature:

Fig. 5.9: Surface Consumption Rate (SCR)

V1 T1

= V2 T2

Amonton’s law: for any gas at a constant volume, the absolute pressure of the gas is directly proportional to its absolute temperature:

p1 T1

= p2 T2

Avogadro’s law: a gram-mole of any gas (molecular weight in grams) has a specific number of molecules; i.e. 6.022⋅E23 molecules per gram-mole. This implies that one gram-mole of any gas will occupy a volume of about 22.41L at STP. The general gas law is a combination of Boyles, Charles’ and Amonon’s law. It can be used to predict the behavior of any quantity of gas in terms of absolute pressure, volume, and absolute temperature:

SCR at Rest: ∆p 80bar, using a 10L cylinder gives a surface equivalent volume of 800L; diving down to 20m increases the ambient pressure by a factor of 2, reducing the net volume to 800/2 = 400L. with 20min bottom time gives a breathing rate of 400/20 = 20L/min in reference to the surface

SCR at Rest: ∆p 60bar, using a 10L cylinder gives a surface equivalent volume of 600L; diving down to 20m increases the ambient pressure by a factor of 2, yielding a net volume of 600/2 = 300L. with 5min bottom time gives a breathing rate of 300/5 = 60L/min in reference to the surface.

p1⋅V1

T1 = p2⋅V2

T2

Thus the air consumption underwater increases proportionally to the increasing depth (increasing absolute pressure). Henry’s law: at a given temperature, the weight of gas dissolved by a liquid is directly proportional to the partial pressure of the gas upon the liquid. The amount of a gas that will dissolve in a liquid is dependent on the pressure of the gas on the liquid (i.e. is proportional to the pressure of the gas in contact with the liquid – see fig. 5.10). At a given temperature, the weight of a gas dissolved by a liquid is directly proportional to the partial pressure of the gas upon the liquid. When the pressure on both sides of a membrane becomes equal, there will be no further change; a state of equilibrium will have been reached.

Fig. 5.10: Henry’s law; a dynamic process

Dalton’s law: the total pressure exerted by a mixture of gases is equal to the sum of the pressures that would be exerted by each of the gases if it alone were present and occupied the volume. Since volume is directly proportional to the number of moles of gas present (constant temperature and pressure), the pO2 is then given by:

pO2 = __VO2__ VO2+VN2

⋅pΣ VO2/VΣ, Volum. ratio

p, pressure [-] [atm]

e.g. at a depth (10m) where the pΣ is 2bar, the O2 content in air should be reduced by 10% (volumetric) to maintain the same pO2 of 0.2bar.

The partial pressure of any component gas in a mixture can be found by multiplying the fraction for that gas by the total pressure of the gas mixture (fig.5.11). Dalton’s law is important to divers because the air (breathing gas mixture) that the diver breathes at depth is delivered by the regulator at ambient pressure and the diver is subjected to that pressure. The table to the right shows the rise in partial pressure with increasing depth. At sea level, a human dissolves about 1L of N2 gas in her/his body tissues.

abs. ptotal

Depth pN2

[kPa] pO2

[kPa] %N2 %O2

1 atm 0 79 21

79 21

2 atm 10 158 43

3 atm 20 237 64

Fig. 5.11: Increase of partial pressure with depth


Breathing compressed air at a depth of 30m (3+1bar) the partial pressure of N2 triples and along with it the volume dissolved in the human body. Although facing a reduced lung capacity while immersed, the increased ambient pressure increases the solubility product of gasses that go into solution. At sufficient partial pressures, gases breathed, whether N2, O2, or contaminants like CO, can have adverse or dangerous effects on a diver (see next Chapter 6, Fitness, Respiration & Circulation). Energy Energy is the capacity to do work and can exist in several forms: i) Mechanical energy (potential or kinetic energy) resulting from movement or storage of a body; i) Thermal energy (potential heat): the energy of molecular motion; i) Electromagnetic radiation (wave): the energy of radio waves, infrared (IR), light (VIS), ultra-violet (UV), X-

rays, etc.; i) Chemical energy (enthalpy of reaction): energy released from chemical reactions; i) Electrical energy (electrical potential): the energy of moving electrons; i) Nuclear energy (fission and fusion): atomic forces; Light Out of the energy concepts outlined above, IR, VIS, and UV, are the most relevant for a SSD. Light experiences various forms of modification upon interaction with matter (fig. 5.12): i) Refraction: refers to the bending of light rays as they

pass from one medium (density-1) to another (density-2); light travels about 25% slower in water. As our eyes are made to focus on land, a dive mask is required as a necessary interface to avoid blurred vision. The use of this prosthesis results in magnification due to change of medium density. Thus, objects viewed through a mask appear about 4/3rd larger and about ¼th closer, than they really are.

i) Absorption: refers to the change in the color and intensity of light as it passes through water.

Fig. 5.12: Refraction, absorption, diffusion, and

reflection of light i) Diffusion: is the scattering of light as it interacts with water molecules; diffusion accounts for the loss of color

underwater; a high enough particle load suspended in water diffusion and absorption occur rapidly. Thus, light penetrating into the water decreases with depth until to the point where no light is able to penetrate (aphotic zone).

i) Reflection: occurs when light waves hitting a surface under a particular angle bounce of a surface; especially if the surface is calm, the diver on a night dive shining against the surface at a flat enough angle, can see the beam of the torch reflected back into the water.

Sound Sound travels better through denser media; the closer the molecules of a medium are stacked together, the more efficiently sound is transmitted through that medium. Humans perceive the direction of sound because our brain is able to measure and interpret the difference in time between the sound reaching our two ears. In water sound travels 4 times faster (1440m/s) than in air (330m/s), thus the time differences (∆t) needed to discriminate between the two ears is too short (fig. 5.13). Sound relocation underwater for humans is almost impossible.

Fig. 5.13: Locating origin of sound


Heat Being comfortably warm is the difference between having an enjoyable and a miserable dive experience. Exposure to cold water is not only uncomfortable, it can lead to life-threatening 2ndary effects (hypothermia is just a precursor to DCI ore even DCS). Body heat is generated in many ways as it is transferred from places of higher temperature into places of lower temperature via conduction, convection, and radiation (fig. 5.14): Heat Capacity: is the heat absorbed by a material in joule per degree Celsius in terms of the actual amount of material under consideration (stored body heat). Conduction: is the transfer of heat by direct contact in solids or fluids at rest (the net energy flow from warmer to cooler matter). It is most evident when skin diving and improves with suit diving. As seawater is a good heat conductor (poor thermal insulator) more body heat is lost while swimming than cycling under the hot sun (with air being a better thermal insulator).

Fig. 5.14: Heat loss due to conduction, convection,

and radiation

Convection: is the transfer of heat in liquid or gases in a state of motion (circulatory patterns of heat); convection becomes evident when using a loosely fitted wet suit, or when wet and the skin is exposed to wind, the loss of body heat becomes apparent due to cooling effect of water evaporation on the skin. Radiation: is the transfer of heat that takes place without any material carrier; body heat is usually irradiated as infrared radiation. Likewise it is picked up from the sun if the body is exposed to it. Propulsion, Drag, and Trim As water is about 1100 times denser than air, several forces act on the diver. As mentioned earlier, buoyancy (fig.5.6) is the upward force caused by the displaced water while weight is the downward force due to the diver’s body mass. The diver is able to move forward by the force of thrust and the kick (fig.5.15). Drag: is the force of resistance (friction) to the movement through the water. It acts backwards opposing the direction of travel. The amount of drag is directly related to the cross-sectional area as one moves through the water. The greater the cross-section presented, the greater the friction resisting forward propulsion. Lift: is the upward or downward force that results from the resistance of the water when swimming at an angle to the direction of movement. Trim: is the body attitude in the water (head up, level, head down). Trim is essential to avoid excess water

Fig. 5.15: Trim and Drag: Increased cross-sectional

area is energetically more demanding

resistance which will result in overexertion. If the diver swims with the body lined up with the direction of travel (arms against body, and no “danglies”) the diver present minimal surface area to the water, thus minimizing drag. However, swimming head up or down in the water, waving the arms, or carrying bulky equipment, the drag and the amount of energy expended increase.


6. Diving Physiology – Fitness, Respiration, and Ci rculation Diving Fitness Health and medical considerations: the Dive Medical Exam (fig. 6.1) is made to identify possible risks before beginning a diving program, enabling the proband to make informed decision about what risks she/he is willing to assume. Determining medical fitness for diving begins with a general medical history form reviewed by the physician. It is important to determine the health in the past, past injuries, medication taken regularly, alcohol or drug abuse, mental attitude, tendency to habitual air swallowing, accident-proneness, impulsive behavior, and risk of panic.

Fig. 6.1: Dive Medical sheet18

A comprehensive diving medical includes a chest X-ray and a pulmonary function test to determine the performance of the lungs, blood and urine tests for infectious and metabolic disorders, examination of the CNS, of the eyes, ears, nose, and throat. Resting and exercise electro-cardiograms (ECG) that screens for cardiovascular diseases and exercise tolerance are commonly recommended for males over 40 and females over 50. The initial screening medical exam should be followed by annual exams particularly for divers over 35 and for those with personal or family histories that are of concern, like cardiovascular disease, lung disorders, nervous system disorders, diabetes, ear and sinus disorders, including smoking-drug-alcohol misuse. Nutrition: General nutrition advice to divers is the same as anyone else for good health and reduction of risk for heart disease, cancer, stroke, diabetes, hypertension, obesity, and other health problems. The standards outlined in the food pyramid based on traditional eating patterns of healthy vegetarian peoples of many cultures is shown in fig. 6.2. A healthy diet is high in complex carbohydrates such

Fig. 6.2: The healthy eating (food) pyramid

as grains, legumes, fruits and vegetables, includes lots of water and a moderate amount of plant-based proteins, vitamins, and minerals. A limited amount of alcohol, caffeine, salt, sugar, and saturated fat can be tolerated. Physical Fitness: Aerobic fitness, muscular strength and endurance, as well as flexibility are essential for any diver. Aerobic fitness is the ability of the lungs, heart, and blood vessels to deliver O2 and the ability of the muscles and other cells to metabolise it (fig. 6.3). Regular fin-swimming (snorkelling) is considered one of the best preparative pre-dive exercises. Other activities contributing to fitness are dancing, skating, cross-country skiing, jogging, biking, and of course swimming. Good fitness reduces the risk of heart disease, stroke, diabetes, high blood pressure, high cholesterol, cancers, and many other diseases. A good amount of muscular strength reduces chances of strains and other injuries during diving. Weakness in back, hip, abdominal, and hamstring muscles are key factors in back pain. Muscular endurance reduces the chance of leg cramps and muscular fatigue. Endurance is easily obtained by regularly being involved in moderate weight-lifting practices. Good flexibility reduces the likelihood of strains, pulls, and other injuries. Flexibility can be easily improved with stretching exercises such as Yoga. All these preparatives should be performed under guided assistance to avoid injuries and long term adverse effects.

Fig. 6.3: Aerobic fitness

18 for a detailed description see appendix


Fitness to Dive: apart from physical fitness, any diver must have a valid medical (not out of date). Though, there are contraindications that according to their severity can prevent dives all together or may impose a temporary ban on any diving activity; Absolute Contraindications: Several lung disorders and heart defects are considered to be in complete opposition to diving;

Asthma: it is a respiratory disease involving the bronchial tubes, which carry air from the windpipe to tiny air sacs in the lungs. When a person has asthma, the bronchial tubes are inflamed and hyperreactive and are clogged with mucus. They go into spasms, called asthma episodes, when triggered by a wide variety of substances and circumstances. An asthma episode leaves a person gasping for breath.

Tuberculosis: TB, or tuberculosis, is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria can attack any part of your body, but they usually attack the lungs.

Emphysema: it is a lung disorder in which the healthy elastic sponge-like tissue is damaged and does not squeeze the air in and out properly. It is as though the lung tissue has become perished, similar to an old flabby football bladder or car tyre tube. This means that the air cannot move in and out of the air sacs easily. The elastic function of the lung is lost.

Chronic bronchitis: it is an inflammation of the lining of the bronchial tubes. These tubes, the bronchi, connect the windpipe with the lungs. When the bronchi are inflamed and/or infected, less air is able to flow to and from the lungs and a heavy mucus or phlegm is coughed up.

Diabetes type I: Insulin Dependent Diabetes Mellitus (IDDM) occurs in 10% of all people with diabetes. This type tends to appear suddenly and progresses rapidly. The pancreas stops (or nearly stops) producing insulin, therefore insulin has to be injected to stay alive. Type I diabetes cannot dive!

Epilepsy: it is a chronic disorder characterized by recurrent seizures. Seizures are defined as passing neurological abnormalities caused by unregulated electrical brain discharge, a direct result of unusual electrical activity in the brain. Complex- partial seizures (formerly psychomotor or temporal lobe Epilepsy) are characterized by a complicated motor act involving impaired consciousness.

Angina pectoris: is a recurring pain or discomfort in the chest that happens when some part of the heart does not receive enough blood. It is common symptom of coronary heart disease (CHD), which occurs when vessels that carry blood to the heart become narrowed and blocked due to atherosclerosis. Patients with angina are at an increased risk of heart attack compared with those who have no symptoms of cardiovascular disease.

Myocardial infarction: it is the death of a section of the myocardium, the muscle of the heart, caused by an interruption of the blood flow to the area. Commonly referred to as a heart attack.

Coronary Artery Disease (CAD): The coronary arteries are blood vessels that carry blood and oxygen to the heart muscle. When these arteries become clogged with fatty deposits called plaque, it is called coronary artery disease. CAD is sometimes called coronary heart disease (CHD). Clogged arteries can keep the heart from getting enough blood and oxygen and can cause chest pain (angina). If a blood clot forms, it can suddenly cut off blood flow in the artery and cause a heart attack.

Cardiovascular Disease: see CAD Nervous System Disorders: the central nervous system, or CNS, comprises the brain, the spinal cord, and

associated membranes. Under some circumstances, bacteria may enter areas of the CNS. If this occurs, abscesses or empyemas may be established. As pus and other material from an infection accumulates, pressure is exerted on the brain or spinal cord. This pressure can damage the nervous system tissue, possibly permanently. Without treatment, a CNS infection is fatal.

Pneumonia: it is a serious infection or inflammation of your lungs. The air sacs in the lungs fill with pus and other liquid. Oxygen has trouble reaching your blood. If there is too little oxygen in your blood, your body cells can't work properly, and you may die.

Recent surgery: any surgery that leaves stitches that have not yet been removed. Temporary Contraindications:

Pregnancy: some studies on pregnant animals have shown an increased rate of fetal abnormality from decompression sickness, particularly among sheep; different studies in other animals have not shown an ill effect on the fetus. Like many other medical conditions, the available studies on this issue are inconclusive.

Earache: itself is not a disease, but it is a symptom of disease or injury in the external or middle ear. Respiratory infections and Common Colds: the common cold is an infection of the upper respiratory

passages -- the nose, throat, and sinuses. Symptoms include stuffy or runny nose, sore throat, a cough, aching and fatigue, and just a general sick feeling. Sometimes, a cold is accompanied by fever. Lung expansion injuries are often caused by mucus left in the lungs after a severe cold or influenza. As a rule of thumb, refrain of diving for at least twice the time the cold or flu lasted.

Seasickness: as a ship rocks back and forth, the inner ear, which is responsible for sensing direction and maintaining equilibrium, sends confusing messages to the brain, causing nausea.


Hernia: A hernia occurs when one part of your body - usually the intestine - protrudes through a gap or opening into another part of your body. Sometimes this happens when you strain or lift something heavy.

Swimmer’s ear: is an uncomfortable bacterial infection of the external ear. Cotton swabs and finger cleaning interrupt automatic cleaning mechanisms and push debris back into the ear. Stripping away the natural protective wax from the ear canal leaves the ears moist after diving - ideal condition for the proliferation of bacterial growth.

SUB-Related Contraindications:

Alcohol: any of a class of organic compounds characterized by one or more hydroxyl (OH) groups attached to a carbon atom of an alkyl group (hydrocarbon chain). Alcohol is hydrophil; it enters all cells (except adipocytes) and is toxic to all cells. Metabolism of alcohol generates aldehydes, which are also water-soluble and toxic. Alcohol and aldehyde disturb many biochemical pathways. Alcohol has no nutritive value, depresses appetite and prevents the absorption of nutrients.

Tobacco: cigarette smoking increases the risk of bronchitis, emphysema, lung cancer, cardiovascular disease, high blood pressure, and other conditions that reduce the quality and length of life. Cigarette smoke contains a fair amount of CO, which has a far better affinity to haemoglobin than O2. One cigarette elevates CO-blood levels for up to 8 hours.

Over-the-Counter Medications: certain non-prescriptive drugs reduce mental alertness, and the ability to judge a situation appropriately.

Recreational Drugs and Drug Abuse: such socially accepted and legal drugs as alcohol and nicotine have been excluded, and "drug abuse" has been limited primarily to heroin, marijuana, stimulant and depressant drugs, and hallucinogens.

Food: Diving after a heavy meal significantly increases the risk of a dive accident.

Relative Contraindications: an illness resolved after a risk assessment was made in which the dive leader established that someone desperately WANTS to conduct this particular dive (this should be seen as a relative contraindication).

Persons with disabilities: deaf persons with knowledge of ASL theoretically could manage a dive successfully; be aware though, that such people tend to overreact due to excitation and the ability to “talk” to each other underwater.

Hypertension: when the systolic/diastolic pressure exceeds 135/85. Someone with hypertension is more than twice as likely to develop heart disease and six times more likely to have a stroke. High blood pressure can cause blindness and also severely damage your kidneys.

Chronic pain: Fiendishly, uselessly, pain signals keep firing in the nervous system for weeks, months, even years. There

may have been an initial mishap - a sprained back, a serious infection - from which you've long since recovered. There may be an ongoing cause of pain--arthritis, cancer, and ear infection. But some people suffer chronic pain in the absence of any past injury or evidence of body damage.

Congenital Defects: diseases that are inherited. Allergies: an allergy is in fact an abnormal reaction by the body’s defence system (immune system) when

the human organism is exposed to its animate or inanimate environment. Allergies are classified in: Type I: atopic syndromes as observed in bronchial asthma, neurodermitis (atopic eczema), Hay fever (allergic rhinitis). Type II: allergic reactions to drugs, transfusions, or stings; in particular allergic reactions to certain venoms of sea creatures (risk of anaphylaxis). Type III: gradual destruction in alvoli of the lungs (exogenic allergic alveolitis = farmer’s lung). Type IV: contact allergies

Mental Instability: psychological stress with partner, dive buddy, team, etc. Fatigue: as with any activity, a tired body and a non-alert mind drastically increase of a dive-related accident. Rest extensively between dives (avoid squeezing 3-4 dives into one day).


Respiration In inhalation, the main gas required to keep body cells alive is O2, whereas CO2 is a metabolic by-product that must be gassed off during exhalation. If ambient pO2 levels fall below 14kPa of normal levels (hypoxia) numbness is experienced. O2 levels of about 10kPa result in sleepiness, whereas 8kPa brings about coma and a further reduction to 6kPa tissue necrosis (anoxia). O2 is taken up by the lungs, chemically attracted to haemoglobin and supplied to the target tissue with the bloodstream (fig. 6.4). The air a diver breathes passed through the mouth down to a junction of 2 tubes - the stiff trachea, where air continues down to the lungs, while the other one just behind it, constitutes the muscular oesophagus which pushes and squeezes food via peristalsis down to the stomach. The epiglottis in charge of separating the two tasks of breathing and swallowing from being mixed up. From the larynx, the trachea continues down into the chest where it divides into two bronchi that represent the entry and exit-ways of the lungs. The deeper down the lungs, the more the bronchioles divide like the branches of a tree. After about the 20th division, where the velocity of the gas stream is allows diffusion across a membrane, alveoli come into place. About 300⋅E3 of these are the air-exchanging units cluster in each lung. Separated by a surfactant and a on cell-layer thick membrane, each alveolus is imbedded in a dense network of capillaries where O2 is swapped for CO2. A thin double membrane called pleura surrounds the lungs, which anchor the lungs to the rib cage. The tiny pleural cavity is filled with fluid not only lubricates the sliding parts, but also makes sure that expansion of the rip cage results in a suction force which is necessary to passively ventilate the lungs. Damage to the pleural cavity can allow air to enter breaking the suction effect, making rib-cage ventilation impossible and ultimately may result in the collapse of the lungs. With an intact pleural cavity, the rib cage prevents the collapse of the lung flaps allowing stomach driven ventilation via the diaphragm.

Fig. 6.4: Respiration anatomy

Ventilation Breathing in and out is possible because the bellows-like activity of the diaphragm and expandable rib cage. A bottomless jar surrounding 2 balloons and closed off with a rubber membrane is a simple representation of lung ventilation. To inhale the diaphragm pulls downwards, enlarging the chest volume and thereby dropping the pressure (p·V = constant). The chest volume is usually at a negative gauge pressure (to keep the lungs open against their surface tension): the lung pressure is negative enabling air to flow in. When the chest compresses and the diaphragm moves up, the chest pressure rises, the gauge pressure in the lungs become positive, and air is expelled (fig. 6.5).

Fig. 6.5: A simple ventilation model


Lung Volumes and Capacities Tidal Volume: The volume of air that a diver can breath in and out is called the tidal volume (fig. 6.6). At rest is about 500mL. With some 12-16 breaths per min., this amounts to a total tidal volumetric rate of 6-8L/min. Vital Lung Capacity: the biggest breath one can exhale after a likewise big inhalation is the vital capacity. It is determined by the size and age of a person, and decreases with age. Residual volume: even after forcefully expelling all air, just about 1000mL still remain in the lungs. It is the residual volume required to prevent the lungs from collapsing. Another vital function of the lungs is filtration. Besides filtering out larger aerosols, lungs are also effective filtering organs in the reverse sense. The alveoli are capable of degassing micro-bubbles from the blood stream into the alveolar sacs, reducing the danger of arterial gas embolism (EAR) that would otherwise occur if the bubbles would reach the heart and / or brain.

Fig. 6.6: Spirogram of lung volumes and capacities

O2 is passed on from the alveolar sac via a diffusion barrier to the red blood cells. The passage of gas from the area of high concentration to an area of lower concentration is known as diffusion, and occurs until equilibrium is reached (fig. 6.7). The blood’s role consists not only in bringing oxygenated blood to target tissues throughout the body but also to provide each organs’ cell with energy, amino acids, and other essential nutrients. Hemoglobin enables each red blood cell to loosely bind as many as 4 O2 molecules to form oxy-hemoglobin. Oxygenated (arterial) blood looks bright red, while deoxygenated (venous) blood has a dark reddish color. This affinity to carry O2, comes for a price as CO is able to bind 200x stronger to hemoglobin, making it very problematic when breathing CO-contaminated filled tank air (discussed further below).

Fig. 6.7: Exchange of O2/CO2 in the lungs and tissue

(*) tissue pO2 can fluctuate between 5kPa (rest) and 3kPa (heavy work)


Circulation The blood consists mainly of red blood cells containing the O2-binding hemoglobin, white cells required for the disease response and platelets platelets needed for wound healing. All those components are suspended in the liquid portion termed plasma; it contains the immune response, sugars, nutritional compounds, and other substances. From the lungs, oxygenated blood is directly pumped into the left atrium of the heart (fig.6.9). From there it is pressed into the left ventriculum. With every full contraction the arteries pumps the oxygenated blood into the ever finer branching system of arterioles, and capillaries. This branching brings a net reduction in the speed of flow, to such a point that in the capillaries it flows so slow, making diffusion of gases (O2/CO2) and nutrients possible. At rest, each cell in the body uses little O2 - that’s why mouth-to-mouth resuscitation can work even with lowered partial oxygen pressure (the air exhaled still contains about 17% O2 – compare with fig, 6.7). Exercise though, increases O2 demand of the cells stripping not only more O2 from the oxygenated blood, but also demanding for a faster supply of oxygenated blood to the cells. Breathing in more O2 won’t increase a person’s ability to extract more O2, but rather increases the likelihood of getting hyperventilated. Only regular exercise will pave the way for increased efficiency in O2 utilization; e.g. snorkelling.

Fig. 6.8: General plan of circulation

Once O2 is delivered and CO2 released into the blood, capillaries join together to form venules which increases the speed of flow until it reaches the veins (Vena cava – fig. 6.8), that brings back deoxygenated (but not entirely stripped O2) blood to the right atrium / ventricle of the heart. The oxygenated blood enters the right atrium from the Vena cava, passes into the right ventricle and is pumped to the lungs via the pulmonary artery. Oxygenated blood passes from the pulmonary veins into the left atrium, is squeezed into the left ventricle and is then pumped out the aorta. As the arterial blood pressure is slightly higher than the venous blood pressure, the left chambers of the heart are more muscular than the right half.

Patent foramen ovale (PFO) or interatrial septum defect is an opening in the interatrial septum (cardiac wall separating left from right atrium) that normally closes at birth and later forms a depression called the Fossa ovalis – see inlet of fig. 6.9. Unfortunately, in up to 30% of the adult population, this flap does not seal entirely. As pressure in the right atrium is about 500Pa lower, blood flows from the left to the right without going through the systemic circulation, allowing a certain amount of oxygenated blood to be shunted off and mixed with deoxygenated blood. A PFO receives much attention in diving, because the larger micro-bubbles originating from the venous system (lower blood pressure) can merge with the arterial system and it’s quite smaller micro-bubbles (higher blood pressure), upon merging, resulting in even larger macro-bubbles. This may explain why victims with PFO show an increased severity of DCI and DCS.

Fig. 6.9: Anterior view of frontal heart sectio


Effects of Immersion on Circulation Normal blood pressure in humans at sea level is more or less equivalent to that show in the figure on the right. As the heart goes through its pumping cycle, the pressure in the main vessels fluctuates. The systolic and diastolic pressures are the maximum and minimum values developed in the arteries. The diastolic and systolic pressure differences in females is about <10% lower than that of males (fig. 6.10a). During immersion, the altered ambient pressure exerted upon the body, the negative pressure breathing (see Chapter 13 Diving Equipment - Regulators), and the more or less horizontal body position, causes blood to centralize at the central thorax area. Blood pooling results in reduced lung volume and a slightly increased blood pressure detected by the pressure sensors in the arterial wall. The detection of this seemingly “extra fluid”, triggers a physiological response that releases hormones which signals the kidneys to get rid of some fluid to normalize blood pressure, resulting in increased diuresis and the urgent need to urinate (fig. 10b). Unfortunately, with the increased excretory turnover of the kidneys, less water is available for the N2 to be dissolved while breathing under pressure, increasing the likelihood of gas embolism.

Fig. 6.10a: Blood pressure in an adult

human male

Fig. 6.10b: Pressure natriuresis; two ways in which the arterial pressure can be increased; left, by shifting the

renal output curve with higher ambient pressure (diving); right, by increasing the intake of salt and

water.

In order to compensate for this physiological response, divers should drink at least 0.6L of water before and 0.6L after the end of each dive. Likewise, blood donors should refrain from giving blood at least two days prior an intended dive. Circulatory and general Physiological Problems Cramps: a cramp is a muscle spasm producing pain and temporary disability. The most common cause of leg cramps is kicking wit stiff, rigid ankles. Cramps also occur when a muscle is suddenly asked to contract beyond its usual shape. Upon occurrence of a cramp, bend back the affected muscle and gently massage. Cramps can be prevented by eating banana (source of potassium). Carotid sinus reflex: the carotid arteries are the main vessels carrying blood up to the brain. Where these arteries fork up, there is a small bulge (sinus). As these sini contain baro-receptors that detect blood pressure, externally applied pressure can falsely suggest the brain to slow the heart rate to reduce blood pressure. However, using a tightly fitted hood exerts excess pressure onto the Carotid artery (fig. 6.11); thus, reducing the blood flow to and from the brain. This may ultimately result in dizziness, lightheadedness, or even unconsciousness.

Fig. 6.11: Caroitid sinus reflex


Hypothermia (Chilling): results when the diver loses more body heat than can be replaced. True clinical hypothermia is reduction of the diver’s body core temperature. Surface temperature of our body is maintained to about 32°C. If the water temperature is any less than this, the diver slowly gives up heat to the water until the skin temperature matches that of the ambient water temperature. Up to 30% of body heat is lost via the heads surface. The use of a hood can significantly reduce the loss of extra body heat (fig. 6.12). A diver suffering from hypothermia can become incapacitated by cold, starts to shiver, feels tired, clumsy movements, confusion, apathy, difficulty to speak, weakness, confusion, coma, and drowning. Hyperthermia (Overheating): a diurnal upward variation of the body’s core temperature (by 3-5°C) is considered normal.

Fig. 6.12: Hypothermia

If there is no immune response to microorganisms, which likewise results in a rise of body temperature, any temperature increase should be considered dangerous. Overheating results if more heat is generated in metabolism than is lost. The most common way a diver is to overheat when wearing a full exposure suit while preparing to a dive on a hot, humid day. As the diver’s body temperature starts to rise, the diver starts to sweat as part of the normal physiological response (fig. 6.13). The diver can loose so much water (even while diving) that the blood pressure starts to fall significantly, and circulation becomes impaired. If temperature regulation fails, the serious and possible fatal condition of heat stroke may occur. Overheating is often associated with seasickness. Symptoms of overheating include: increasing fatigue, weakness, pale skin, rapid breathing, weak pulse, low blood pressure followed by shock-like unconsciousness. In the case of a heat-stroke, symptoms include headache, high fever, confusion, rapid pulse, hot-flushed skin, eventually, collapse, coma and possibly death. Survivors may suffer permanent brain damage.

Fig. 6.13: Hyperthermia

Obesity does increase the risk of hyperthermia - a thinner wetsuit might help. Again, reduce heat stress by staying well hydrated - drink, drink, and drink plenty of water! Seasickness: this can ruin dive trips all together. The fluid-filled semicircular canals in the inner ear even though motion is the primary trigger, improperly digested food can represent the basis of seasickness. In fact skipping a meal might prevent seasickness from occurring in the first place. Early warnings include feeling of unease and dismay, pallor accompanied with headache, followed by weakness, cold sweat, nausea, continued salivation, and finally vomiting. If vomiting underwater, retain the regulator in place, keep the mouthpiece pulled away from one corner of the mouth to allow materials to flow out into the water, while keeping the purge button pressed to prevent clogging. Disorientation: this is a loss of sense of direction or position. A person’s connective and muscle tissue is dotted with little proprio-receptors, that tell the brain about the position of body parts. The vestibular system in the inner ears provides information about the body’s position in space, while the semi-circular canals register the movements of the body through space. Extra redundancy is provided by visual contacts of the surrounding environment (fig. 6.14). As these orientation systems work hand in hand above water, they are a lot more distorted and limited in its application underwater, especially when neutrally buoyant. With restricted visibility (or super-clear water), a narrow mask, low light levels, the vestibular system can be confused by sloshing and surge, leading to disorientation, not knowing which way is up or down. Blue Orb Syndrome (BOS): is the loss of orientation during pelagial dives; blue ocean water surrounding the diver makes it hard to spot any reference points required for orientation.


Fig. 6.14: Vestibular system

Vertigo: is a hallucination of spinning, rotation (whirling sensation), or whirling and is most probably connected to an improperly functioning vestibular system. Vertigo can be triggered by hyperventilation, using alcohol or drugs, from motion sickness, from inner ear DCS, and from unequal stimulation of the diver’s ears by temperature or pressure. In some cases vertigo can be triggered when using a hood, as cold water enters one external ear canal while the other is kept free, or when using no hood, ear wax is blocking further entry of seawater. Equalizing frequently and early while descending with feet first, often helps to avoid vertigo. Pressure build-up in the middle ear (reverse block) during ascent can produce a similar effect known as alternobaric vertigo. Dehydration: considered an abnormal loss of water that is not replaced. Over a period of a day, a person gains water in the amounts and ways shown in the figure on the right. Overheating during pre-diving preparation can increase sweating. Both immersion and cold stimulate the body to increased diuresis. SCUBA tank air is dry - with each breath the body uses water to humidify the air. Loosing water in that way is not a problem as long as it is replaced. This water balance is kept in equilibrium when a person obtains enough water by eating, drinking and via metabolic activity. As urine constitute the bulk of liquid loss, a shift in water balance (too little liquid) results in more concentrated urine. Thus not all the metabolic waste products can be eliminated via the kidneys gradually poisoning the body (fig. 6.15).

Fig. 6.15: Water loss and gain – a balancing act

This effect is know as dehydration; it reduces heat tolerance and the ability to work, brings early fatigue along with an increase heart rate, and leaving a dry mouth. As body fluids in a dehydrated diver become viscose (thicker), chances of suffering from DCI are higher as fewer amounts of fluids are available to dissolve the increased pN2. Remember to drink plenty before and after each dive. Excellent fitness conditions the body to exercise in heat. Water intoxication (excess consumption of H2O) is rare, but can occur if the person drinks a lot without providing extra minerals and salts lost during sweating. Generally men lose a higher percentage of their body weight in sweat than women, leaving males more prone to dehydration than females.


Breathing Problems Breathing resistance: the density of the breathing gas coming from the SCUBA tank rises with increasing depth. Denser air is so to speak “thicker” and requires more work to breathe. Experiencing increased breathing resistance will ultimately lead to less oxygenated blood (reduced pO2 levels). Chemo-receptors in the medulla detect rising blood CO2 levels, while other receptors in the carotid arteries and aorta may activate breathing if blood O2 levels become dangerously low. Such circumstances ultimately shorten the available bottom time, as extra effort is needed for breathing. Experiencing breathing resistance has been implicated in some diving accidents. Cheap or improperly tuned regulators increase the workload on the respiratory system. A good quality regulator will start to free-flow upon immersing it into the water with the mouthpiece facing up. Hyperventilation and Shallow-Water black-out: hyperventilation lowers pCO2 in a person, suppressing the immediate need to breathe. But breath-hold diving for example uses O2 quite quickly (fig. 6.16). In snorkellers shallow water blackout can be triggered when hyperventilating more than 4 times (up to 10 or even 20 times) for breath-hold diving. Chemoreceptors in the arterial wall signal an elevated pO2-level. Initially, diving down to depths of 10m still poses no problem. As the dive proceeds, maybe into the 2nd minute, the partial pressure of O2 drastically sinks, while that of CO2 soars. According to Dalton’s law, an ascent to the surface causes the partial pressure of O2 to sink even further, reducing the available O2 reserves. At that stage and in order to maintain essential body functions, the brain shuts down all unnecessary O2 consumers, rendering the diver unconscious, shortly before reaching the surface. Hyperventilation can also be induced by emotional factors; find out what is frightening and abort the dive. Ascend normally to the surface and stop diving until the causes are resolved.

Fig. 6.16: Blackouts in skin diving

Overexertion: even though poor equipment status, improperly trimmed, and not neutrally buoyed may facilitate it, the major reason for it is being out of shape for a particular task. Effects of overexertion include air hunger and eventually panic. Overexertion may also result in cramps that usually affect the lower extremities of the legs. Avoid working excessively under water or trying to swim against a strong current even with a proper ventilation rate; stop breathing, rest, and allow breathing to gradually return to normal. In a current, find something to hang on to. Hypoxia: is a deficiency of O2 at the tissue level without killing the cells. Based on the cause, hypoxia can be based on Hypoxic hypoxia (low pO2 in the arterial blood; the type divers are exposed to), Anaemic hypoxia (too little functioning haemoglobin), Ischemic hypoxia (too little blood flow), and Histotoxic hypoxia (target tissues are unable to take up O2 due to poisoning). In any case, when tissues receive too little O2, they turn hypoxic; micro-gradients within cells can even turn anoxic. The imminent signs of hypoxia are drowsiness, incoordination, headache, double vision, possible euphoria, apathy, cyanosis (lips, mouth, fingernails), rapid pulse and breathing, convulsions, unconsciousness and eventually death. If the victim as a result becomes unconscious, then this represents a life-threatening situation, immediate O2 must be administered (EAR if necessary). Blood O2-levels dwindle almost instantly when circulation is still working. Resuscitation with pure O2 increases the delivered pO2 and helps to offset this effect. As 100% oxygen is a combustion booster it also is capable of substituting the balance of partial pressures in favour of oxygen. As it does not add any extra N2 into the system, delivering O2 is beneficial for DCI victims as it increases the pO2 and “forces” the N2 out of the tissues into the blood and out via the lungs; thus reducing the likelihood of long term negative effects. Chapter 13 (Oxygen Provider) extensively deals with O2-administration. Cyanosis: is the change of skin colour to slightly bluish, dark purple skin coloration, most easily seen in the nail beds and mucous membranes, due to hypoxia.


Drowning and Near Drowning: while drowning is guaranteed death, near drowning offers a chance of survival and is closely linked to cell osmosis. Water penetrating the larynx shuts it off in a reflex called laryngospasm; it simply blocks water from penetrating the lungs, but at the same time increases the chances of suffocation (drowning people do not inhale air, but die from hypoxia - lack of air due to the spasm). Saltwater Aspiration: Fluid build-up in the lungs, on the other hand, is caused by inhalation of seawater. The osmotic effect of it forces fresh water through the surfactant into the alveoli of the lungs, gradually developing into water filled cavities (fig. 6.17). Fluid building up in the lungs can lead to pneumonia and the fatal condition of 2ndary drowning. A faulty regulator or a crack in the mouthpiece is sufficient to for the inhalation of saltwater. Even though the mouth feels less dry, the accumulated saltwater in the lung can cause similar effects like near drowning, and usually will manifest itself only long after the dive by obvious chest pain (heavy breathing with pneumonia-like symptoms). The surfactant in the alveoli is needed to reduce surface tension, and is easily washed away when in contact with water - water-filled alveoli can’t perform gas exchange.

Fig. 6.17: 2ndary drowning; the salty water exerts a negative osmotic pressure (turgor) onto the lining of

the alveoli, resulting in a gradient that causes fluids to leak out into the alveoli.

Other manifestations are similar to hypoxia, i.e. bluish skin (cyanosis), no breathing, and or no pulse. Permanent brain damage may result after only 4-5min of hypoxia. The Gasp Reflex and Dive Reflex: although quite different to (near) drowning, both can be lethal. The gasp reflex can be defined as the sudden uncontrolled deep inhaled breath one experiences on jumping chest first into cold shower; it can result in aspiration of water and asphyxiation. Folding the arms across the chest or holding a cushion or life jacket close to the front of the chest can prevent it (fig. 6.18). The dive reflex involves the nerves in the face i.e. the trigeminal nerve to the check area signal the heart rate to slow down (bradycardia), to decrease blood circulation into the extremities, and closing of the glottis over the entry of the trachea. Peripherals are shut down of the major arterial blood supply to keep the body core temperature at 37.2°C.

Fig. 6.18: Safe entry into cold water

Bradycardia can lead to irregular heartbeats (arrhythmias) and can pose a problem to people with heart disease. Actual cardiac arrest has been reported as the result of the dive reflex (dry drowning). Covering both sides of the face with the hands can prevent the drive reflex. In some individuals, the exposure of the front face to cold water (e.g. while jumping into the water and the mask slips off the face) can trigger an asthma-like attack, which suddenly reduces the overall cross-sectional area of the bronchi and bronchioles. Upon exhalation, it brings about a drastic reduction in the total flux of air per time unit, causing the victim to literally drown due to lack of oxygenated air (hypoxia). Cold water drowning victims are usually predisposed candidates for CPR.


Diving Maladies – Signs and Symptoms Remember react immediately to the signs. Often symptoms are masked and along with denial (it’s nothing), the affected diver enormously increases the risk of serious DCS (including the body, so listen to it!). In fact, denial is quite common and the trigger to more serious incidents (always listen what your body has to tell). As the human body contains several air-filled spaces, a barotrauma describes injuries due to changing pressure conditions while diving. Lung-Barotrauma: it occurs when pressurized air in the lungs can’t escape while ascending to shallower depths. Muscle tissues is capable to withstand strains to a certain degree. Whereas, lung tissue, being a passively ventilated spongy tissue, does not possess this rigid property. Due to Boyle’s law (p⋅V = constant), holding the breath while resurfacing causes over-pressurization of the lungs. Lung Barotrauma is the main reason divers are so vigorously taught“, never to hold their breath” as interrupted breathing is a conditioning factor for such a severe injury. Pneumothorax: is an injury that allows air to enter the intrapleural space via the alveoli. The otherwise sealed off intrapleural space is filled with air, surface tension and recoil of elastic fibres cause the lung on the affected side to collapse. Collapse or incomplete expansion of lung tissue is called atelectasis (fig. 6.19). Although a collapsed lung is quite infrequent, it occurs as lung over-expansion ruptures the pleural lining of the diver’s lungs and the degassing air escapes into the small, normally fluid-filled pleural cavity. Spontaneous pneumothorax is an occasional observation in smoking young adults. Symptoms may include chest pain, breathing difficulties, reduced chest movement on the affected side, leaning onto the injured side, shock, and cyanosis! In severe cases, such as rapid ascent and suppressed breathing, the lungs pop out through the diver’s mouth. Breathing normally and exhaling while ascending to the surface can easily avoid lung Barotrauma.

Fig. 6.19: Pneumothorax

Thoracic Squeeze: as it is quite rare, it is only observed in breath-hold diving beyond depths of 40m. It occurs as pressures at these depths squeezes the lungs beyond residual volume as blood shifts from the chest to the extremities. However, on ascent, the reverse is happening re-inflating the lungs as long as the person does not exhale underwater at significant depth. Loosing consciousness may bring about exhalation, and is in detailed described in shallow-water blackout. Middle Ear Barotrauma: the middle ear is connected for drainage and ventilation to the throat by the Eustachian tube (fig. 6.20). This connection is normally closed and only opens up when swallowing or during forceful equalization during descent. Delaying clearing during descent causes ambient water pressure to seal the Eustachian tube, preventing equalization (trapdoor effect). Slightly ascending to shallower depths until equalization is possible usually reverses blockage and makes equalization again possible. Descending without ear equalization most often results in the rupture of the eardrum(s) (tympanic membrane – lower inlet of fig. 6.10). Although this painful condition can be treated, the formation of scars on the drum almost always results in a loss of sensitivity, i.e. loss in hearing. Other symptoms include fullness in the affected ear, vertigo, and ear ringing (tinnitus). Inner Ear Barotrauma: injuries to these parts mean damage to either of the delicate structures separating the middle ear from the inner ear (oval and the round windows).

Fig. 6.20: Middle ear barotrauma; upper inlet showing

normal eardrum, lower inlet a ruptured eardrum

Uncontrolled middle ear squeeze or pressure equalization can transfer pressure against the oval or round windows, distending them until rupture occurs. The effects of the rupture range from pain and tissue damage, tinnitus, and vertigo to eventually permanent hearing loss.


By simply avoiding forceful and prolonged attempts to clear pressure in the ears, often and regular gently equalization and planning safety stops on every dive prevents this from occurring.

Sinus Barotrauma: while descending or ascending , blockage of the sini of the skull often results in squeezes. Sometimes such blockages result in ruptures of blood vessels supplying the lining inside the sinus. Blood cloths clogging the opening of a sinus cause troubles during ascent, thus reopening the recently closed rupture of the blood vessel (fig. 6.21). Sini barotraumas are evident when the diver resurfaces with a bloodstained dive mask (or just a slight film of blood trapped at the bottom of the mask). In such circumstances the diver should refrain from further dives.

Fig. 6.21: Sinus barotrauma

Dental Barotrauma: tooth decay and incomplete fillings can create air pockets in a diver’s tooth. Existing fillings with poor dental hygiene provide solid ground for dental decay and may deteriorate existing fillings in such a way, that micro-cracks etched out by the bacteria (Streptococcus sp.) allow entry of compressed air into the cavity underneath the filling while descending (fig. 6.22). The reverse happens during resurfacing. Both processes result in painful conditions of the affected tooth. In severe but rare cases an affected tooth can literally explode! Regular check-ups with your dentist can prevent this from occurring. Arterial Gas Embolism (AGE) and Cerebral Arterial Gas Embolism (CAGE): during a rapid scent, micro-bubbles expand and merge to form macro-bubbles. These are capable of becoming stuck while travelling through arterioles and venules, blocking the flow of blood to and from a certain tissue (embolism). Symptoms are eminent and immediate. Blocked blood-flow in the brain (CAGE) result in dizziness, incoordination, paralysis, convulsion, unconsciousness, and eventually death. AGE can form in any tissue; when it occurs in the spinal cord it results in (permanent) paralysis of the associated area (fig. 6.23).

Fig. 6.22: Dental barotrauma

Fig. 6.23: Arterial gas embolism

If it occurs in the coronary arteries, it leads to Angina pectoris or even to heart attack. Therefore, never hold the breath, never practice “skip-breathing” techniques; always ascend slowly, and do not smoke (avoid 2nd hand smoke)! Diving Emphysema: this is an abnormal distension of body tissues (air filled cavities). Mediastinal emphysema as a result of a rapid ascent forms in the lower parts of the lungs and gradually makes its way up under the skin to the diver’s neck evolving to subcutaneous emphysema (itself manifested by a skin rash in the neck area – fig. 6.24). Emphysema of this kind result in pain under the sternum, create breathing difficulties, swelling and due to the pressure built-up possibility of lung collapse along with heart failure. Subcutaneous emphysema on the other hand results in changed pitch of voice, crackling under the skin, and difficulties to swallow.

Fig. 6.24: Medistinal and subcutaneous emphysema

Decompression Sickness (DCS): due to the complexity of this topic it is covered in details in the following chapter


7. DeCompression Illness (DCI) / DeCompression Sick ness (DCS) Differentiation of Decompression Illness (DCI) vs. Sickness (DCS): when a person breathes air under high pressure for a long time, the amount of N2 dissolved in the body fluids increases. Over several hours enough N2 is carried to all the tissues of the body to saturate the tissues with dissolved N2 (fig. 7.1). Because it is metabolically inert, it remains dissolved until the pressure of the breathing gas decreases. As this removal takes hours to occur, a sudden ascent back to the surface can induce DCI. At sea level, almost 1L of N2 gas is dissolved in the entire body; about 48% in water, while about 52% in the fatty tissues (N2 is lipophilic as it is 5 times more soluble in fat than in H2O). The total amount of dissolved N2 is 2L at 10m, 4L at 30m, 7L at 60m, and 10L at 90m. Desaturation of watery tissues is within 1h, but due to the poor blood supply in fatty tissues may require many hours or even days.

Fig. 7.1: Typical pattern of N2 tissue saturation

When ascending too fast, or without a deco-stop from a deeper dive, significant quantities of N2-macrobubbles can develop in the body. The principles in bubble formation are shown in the figure 7.2. The left scan shows the diver’s tissues as they have become equilibrated to a pN2 of 515kPa (5bar, about 6.5 times the normal amount).

Left: saturation of the body to high gas pressures when breathing air at pΣ of 6.58bar (657.9kPa). Right: excess of intrabody pressure that is responsible for macro-bubble formation in the tissues when body is returned to NTP.

When the diver suddenly rises to sea level, the ambient pressure reduces to only 1bar, whereas the pressure inside the body is still the sum of the partial pressures (534.9kPa). A pressure exceeding ambient pressure and is 97% based on N2-builup. This sudden reduction in pressure cause bubbles to plug the small blood vessels (fig. 7.3).

Fig. 7.2: Physical responses to pressure change

Often these bubbles may not appear for many minutes to hours because N2 can remain dissolved in a “super-saturated” conditions. Increased exercise can shorten this latent period, just as shaking a soda bottle facilitates degassing. Decompression Illness is considered less severe as Decompression Sickness, as the former only involves post-diving pain, while the latter includes gas embolism due to expansion and the agglomeration of micro-bubbles resulting in formation of macro-bubbles in the blood stream. It is the result of staying too long underwater, diving too deep, or ascending too quickly. Generally micro-bubbles are generated after every dive, but efficiently filtered out as they are gassed off in the lungs. DCI / DCS can occur even 48hrs after a dive!

Fig. 7.3: Degassing bottle of soda


Types of DCS: Bubbles can both mechanically and chemically damage a diver’s body. They might squash a vessel and nerves from outside or obstruct them from within. White blood cells and platelets clump onto the macro-bubble triggering a complement activation immuno-response. Predisposing factors are thought to include dehydration, CO2 retention, hypothermia, exertion, post-dive exercise, fatigue, smoking, alcohol consumption, lack of fitness. Effects of DCS start from minutes to hours after resurfacing and span a spectrum from mild to severe symptoms: DCS-I: piercing pain observed in one of the extremities (joints, shoulders), usually the limbs, but also the skin

(itchy rash), inner ear barotrauma, chokes along with white (foamy) sputum. DCS-II: any kind of neurological symptoms associated with the central nervous system (CNS), like numbness in

the extremities, vomiting, dizziness, difficulties to urinate, loss of bowel, temporary impotence, etc. Statistics suggest that 3.4 per every 10000 recreational divers suffer from DCI. If a diver experienced a DCI incident, she/he should at least wait several months (1-3 months) before diving again. Synonyms of DCS: Bends, Compressed Air Sickness, Caisson Disease, Diver’s Paralysis, Dysbarism. Symptoms of DCS Gas bubbles blocking blood vessels in various tissues are responsible for most symptoms. At first, only the smallest vessels are blocked by macro-bubbles, but as the bubbles coalesce, progressively larger vessels are affected. Tissue ischemia and sometimes necrosis are the result. In mild cases symptoms include fatigue due to neurological effects of N2, headache, vomiting, numbness and tingling in extremities. In most people with DCS (about 95%) the symptoms are tingling, pain in the joints and muscles of the legs (especially in the shoulders and the hips), tight gut, marbled skin rash on the torso (Cutis marmorata and maculopapular rash – fig. 7.4).

Fig. 7.4: Skin mottling (Cutis marmorata)

In 5 to 10% of DCS victims, CNS-related symptoms occur, ranging from dizziness to paralysis or collapse and unconsciousness, loss of leg control (stroke-like symptoms), loss of bladder control, (inability to urinate), general malaise; sometimes the damage is permanent. Finally in about 2% of all cases, the victims develop “the chokes” (coughs with whitish sputum that sometimes can be mixed with blood), caused by massive numbers of macro-bubbles plugging the capillaries of the lungs, characterized by a serious shortness of breath, followed by pulmonary oedema, and occasionally death. Pulmonary Oedema refers to an abnormal accumulation of interstitial fluid in the interstitial space and alveoli of the lungs. The oedema may arise from increased pulmonary capillary pressure (less from permeability) due to macro-bubbles rapidly gassing off via the alveolar capillaries. The most common symptom is dyspnea (painful or laboured breathing), wheezing, tachypnea (rapid breathing), restlessness, feeling of suffocation, cyanosis, pallor (paleness), and diaphoresis (excessive perspiration). As diagnosis of a pulmonary oedema requires experience from an expert, it is not further covered here, except that 1st aid consists of administering O2, which is extensively covered in Chapter 11 (Oxygen Provider). Necrosis is cell death due to inflicted injures. In necrosis, many adjacent cells swell, burst, and spill their cytoplasm into the interstitial fluid. This mess of cellular debris usually stimulates an inflammatory response. Necrosis is another result of the expansion and aggregation of micro-bubbles to a larger bubble of nitrogen gas can result into a blockage of the arteriole, ultimately halting the oxygen-supply of the capillary network attached to it (fig. 7.5). In most cases, necrosis is experienced at the cartilage of the joints (osteonecrosis). As cartilage is supplied with nutrients by diffusion only, tissue death gradually leads to the decay of articular cartilage, that will not regenerate. The formation of dead tissue results in malnutrition of the sinovial fluid between adjacent bones, causing arthritis or in severe cases even cancer.

Fig. 7.5: Osteonecrosis


Risk Factors favouring DCI / DCS Patent Foramen Ovale (PFO): a hole in the arterial wall of the heart is found in about 30% of all humans, this closure does not happen completely, resulting in a significant shunting of oxygen-poor venous blood into the oxygenated arterial system. As the lungs act as perfect micro-bubble filters, a patient with PFO may more likely develop arteriole blockage when the shunted venous blood forms macro-bubbles – see Chapter 6 (Diving Physiology). The risk of DCI increases even further if a PFO patient holds his / her breath while ascending. Due to the lower blood pressure deoxygenated blood is more likely to form macro-bubbles in veins than arteries. Age: it is usually not a problem per se, it is just a question of aerobic fitness; males over 40 and females over 50 should undergo a profound medical exam to verify that no adverse medical facts interfere or increase the likelihood of DCI. Overexertion: Dive tables have been established from individuals under resting conditions. An excess workload increases circulation and metabolism, shortening no-decompression limits. Five Minute Neurological Exam Examination of an injured diver’s central nervous system (CNS) soon after an accident may provide valuable information to the physician responsible for treatment. The 5 minute Neuro Exam is easy to learn and can be performed by individuals with no medical experience (fig. 7.6). The examination can be done whilst reading from this manual. Perform the following steps in order, and record the time, and the results for each test. Basic principles of neurological assessment involve: What to do: 1. record examination, 2. make comfortable & respect privacy, 3. be systematic, 4. observe & question carefully, 5. don’t have any expectations, 6. in any case no further diving, and finally 7. check buddy as well. Performing the Exam:

Fig. 7.6: Rapid field Neuro Exam Record19

1. Orientation : i) does the diver know his/her name and age? i) does the diver know the present location? i) Does the diver know what time, day, year it is? Even though an individual may appear alert, the answers to these question can reveal confusion. Do not omit them.

2. Eyes: Have the diver count the numbers of fingers you display, using two or three different numbers of fingers. Check each eye separately and then together. Have the diver identify a distant object. Tell the diver to hold head still – or you hold it still – while placing your other hand about 45cm in front of the face. Ask the diver to follow your hand. Now move your hand up and down, then side to side. The diver’s eye should follow your pupils and should not jerk one side and return (nystagmus). Check that the pupils are equal in size.

3. Face: Ask the diver to whistle or purse their lips. Look carefully to see that both sides of the face have the same expression whilst whistling. Ask the diver to grit their teeth. Fell their jaw muscles to confirm that they are contracted equally. Instruct the diver to close his / her eyes while gently touching with the fingertips across forehead and face. Confirm that sensation is present, and feels the same everywhere.

4. Hearing: Evaluate the diver’s hearing by holding your hand about 60cm from the individual’s ear and rubbing your thumb and finger together. Check both ears by moving your hand closer until the diver hears it. Check several times and compare with your own hearing. NB: if the surroundings are noisy, this test is difficult to evaluate. If necessary, ask any bystanders to be quiet and turn off unneeded machinery.

19 see Appendix for detailed listing of tasks


5. Swallowing Reflex: Instruct the diver to swallow while you watch their “Adam’s apple” to be sure it moves up and down.

6. Tongue: Instruct the diver to stick out their tongue. It should come out straight in the middle of the mouth without deviating to either side.

7. Muscle Strength: Instruct the diver to shrug their shoulders while you bear down on them, to observe for equal muscle strength. Check the diver’s arms by bringing their elbows up level with their shoulders, hand level with the arms, and touching their chest. Instruct the diver to resist while you pull their arms away, push them back, and move them up and down. The strength should be approximately equal in both arms in each any direction. Check leg strength by having the diver lie flat and raise and lower their legs while you resist the movement.

8. Sensory Perception: Check on both sides by touching lightly as was done on the face. Start at the top of the body and compare sides while moving downwards to cover the entire body. The diver’s eyes should be closed during this procedure. The diver should confirm the sensation in each area before you move to another area.

9. Balance and Coordination: Be prepared to protect the diver from injury when performing this test. Have the diver stand up with the feet together, close their eyes and stretch out their arms. The individual should be able to maintain balance if the platform is stable. Your arms should be around, but not touching the individual, in case they fall. Be prepared to catch a diver who starts to fall. Check coordination by having the diver move an index finger back and forth rapidly between their nose and your finger – held approximately 45cm from their face. In another test of coordination, instruct the diver to slide the heel of one foot down the shin of the other leg while lying down.

Conduct these tests on both right and left sides, and observe carefully for differences between the two sides. Tests 1, 7, and 9 are the most important, and should be given priority if not all the tests can be performed. The diver’s coordination may prevent the performance of one or more of these tests. Record any omitted tests, and the reason. If any of the tests appear abnormal, injury to the CNS should be suspected. The tests should be repeated at frequent intervals while awaiting assistance, to determine if any change occurs. Report the results to the emergency medical personnel responding to the call. Good diving safety habits include practicing this examination on normal uninjured divers, to become proficient in the test. Following a very tight diving schedule that runs over several months, this simple test should be performed every 3 months; sporadic testing is beneficiary when executing a less intense dive schedule. Treatment of DCI and DCS: Rather than merely exposing a DCI-victim again to pressure by re-submerging her / him to the same pressure conditions experienced during the dive, it is better to administer pure O2 in order to facilitate the re-diffusion of dissolved N2 from the tissues into the blood stream (remember Dalton’s law of partial pressure). Once this first aid measure is applied, the transfer to a hyperbaric pressure chamber can be organized. Compressed Gas Treatment Record Should it ever happen that a diver shows DCI- or even DCS-like symptoms, the treatment record must be compiled in order to keep liabilities that might follow after an incident / accident to a minimum (fig. 7.7). It contains historical data regarding previous dives and most of the supplement information needed for a later investigation on the reasons of the incident / accident. Furthermore it is a document of proof of the 1st aid services provided. For a detailed description of O2 administration see Chapter 11 (Oxygen Provider).

Fig. 7.7: Compressed Gas Treatment Record20

20 see Appendix for detailed listing of tasks


8. Decompression and Recompression Decompression Theories In the early days of bridge construction working, one type of DCS was originally known as Caisson’s disease, or popularly the “bends”. For the construction of the pillage, engineers of the time used a pressurized bell that was placed at the bottom of the river and filled with air to such a pressure that it displaced the water underneath. Workers mining in such a pressurized environment for hours were subject to sudden decompression as they came back up to the surface. The limbs of those stricken, distorted with cramps, compelling them to walk with sticks, and drastically reducing the chances of survival. In 1908 J.B.S Haldane observed that animals (goats) subject to pressurized conditions not exceeding 10m seawater (2atm), could be brought to the surface without showing this effect. The net pressure reduction in such a depth is about 50% (same as for astronauts performing space walks in their semi-pressurized space suits). Extrapolating from this information, Haldane reasoned that tissues could always withstand a total pressure reduction of 50% (Haldane ratio), whether from 10msw to the surface or from 30msw to 10msw. Today’s knowledge clearly objects this as far too liberal and has since been modified to a ratio of 1.58:1. As shown in figure 8.1, the speed which one of these compartments absorbs or eliminates gases is defined by its half-time. The compartment’s half-time is the time required for each compartment to absorbed, degas half of the pressure difference between initial higher pressure and ambient pressure. After the first half-time 50% is degassed with 50% remaining. After another half-time gone by 50% of the remaining has left the tissue, leaving 25% residual gas., etc. Haldane used tissue half-times for various compartments of 5, 10, 20, 40, and 75% to model the animals body. The US Navy slightly improved the safety aspect based on research made with volunteering staff (trial & error). By calculating the maximum allowable tissue pressure by multiplying the N2-ratio by 10msw surface pressure (N2 = 0.79atm at sea level).

Fig. 8.1: Half time diagram of N2 tissue absorption

They also developed a model to address the concept of decreasing super-saturation ratios. This M-value is the maximum allowable pN2 in a specific tissue of the model. The British Royal Navy theory is even more conservative as it utilizes extended surfacing ratios than their US counterparts, reducing the available bottom time. It also includes an extremely conservative repetitive dive procedure, as all repetitive dives are combined and worked as single dives regardless of surface intervals. The Swiss Theory developed by prof. Buhlmann at the ETH Zurich extended the compartments to 16 different tissues with half-times ranging from 2.65 to 635 minutes. The M-values (the maximum allowable N2 pressure in a specific tissue) in this model are not constant but rather based on mathematical algorithms as a function of atmospheric pressure (includes diving at altitudes). As none of these models is an exact representation of the physics and the physiology involved in (de)compression but rather a fitting of mathematical equations to a time-depth history, the Canadian Theory contrasts these models even further. The Canadian Defence and Civil Institute of Environmental Medicine (DCIEM) studied the physiological effect on probands ranging from the 14 to 80 years of age. It employs a set of “serial” tissues, the 1st of which takes up and gives off gas from the environment while the 2nd and succeeding tissues take up and give off gas from the preceding tissues. Tables generated from this theory have been validated using Dopler ultrasonic measurements to detect sub-clinical decompression stress due to silent or micro-bubbles. These tables are considered to provide the best margin of safety, and are therefore used in this course. The Reduced Bubble Gradient Model (RBGM) is based on different tissue 32 compartments and is the current standard used for dive computers. Although it does not make table dives obsolete, it is a good redundant system to make sure that every dive is on the safe side.


Dive Tables NAUI recommends the use of DCIEM dive tables for scientific diving (fig. 8.2). Developed for the Canadian Forces diving unit of the defence and civil institute of environmental medicine (DCIEM). It is a more conservative approach to decompression procedures than those currently published by the US Navy and the Royal Navy. Based on over 20 years of decompression research using the Doppler ultrasonic bubble detector as an aid to detect micro-bubble formation in the veins. Tests were conducted in a hyperbaric chamber which wet-working divers in cold water between 5-10°C.

Fig. 8.2: PADI, NAUI, DCIEM dive tables

The DCIEM Air Diving Tables consists of the following sub-categories (fig. 8.3): Table A Air decompression Table B Surface Intervals Table C Repetitive Diving Table D Depth Corrections for Altitude Diving The tables cover dives up to 45m in depth. The key features used for the table include: Actual Bottom Time (ABT) – the total elapsed time

from when the diver leaves the surface to the time that the diver begins to ascend (given in minutes);

Fig. 8.3: The 4 sub-categories of the DCIEM table

Ascent Rate – a specified rate of rise that the diver must maintain up to and between decompression stops or surface: 15 ± 3m/min;

Decompression Stop (DS) – the length of time a diver must spend at a specified depth to allow for the elimination of sufficient N2 gas from the body to allow safe ascent to the next stop or the surface.

Descent Rate – the maximum rate of travel allowed in descending to the bottom: 18m / min; Effective Bottom Time (EBT) – used in repetitive diving, it is the calculated bottom time for decompression

purposes taking into consideration the depth, actual bottom time & residual nitrogen from the previous dive(s).

Effective Depth (ED) – used in altitude diving. It is the calculated depth of an equivalent dive at sea level. No-Decompression Limit (NDL) – the maximum bottom time which allows a direct ascent to the surface without

requiring decompression stops. Remember: never do a deco dive if a hyperbaric recompression chamber is not nearby!

Repetitive Dive – any dive that has a repetitive factor (RF) greater than 1.0 Repetitive Factor (RF) – a figure used for repetitive diving determined by the repetitive group and the length of

the surface interval after a dive. Repetitive Pressure Group (RPG) – a letter, which relates directly to the amount of residual nitrogen in a diver’s

body immediately on surfacing from a dive. Residual Nitrogen Time (RNT) – the time it takes to remove excess N2 that is still dissolved in a diver’s tissues

after the surface has been reached. Safety Stop – for DCIEM diving it is defined as 3mins at 4.5m, which includes the travelling time to the stop at

15m/min. Stop Time – the tabulated decompression stop which includes the travelling time to that stop at 15 ± 3m/min; Surface Interval (SI) – the time which a diver has spent on the surface following a dive; beginning as soon as the

diver surfaces and ending as soon as the diver starts the descent for the next dive (max. 18hours).


Special Dive Table Procedures The handling of the dive table is shown using the dive profile shown in fig. 8.4. This particular example shows a dive profile covering 4 dives on one day. The surface intervals are 2h 20’, 3h 45’ and 6h 15’ respectively while the depths range from 33m, 27, 21m and 12m. DCIEM Table A (fig. 8.5): 1. to find a 1st dive NDL select the depth and follow

the row of numbers across to the bold vertical lines. The section to the left of the bold lines is used for No- Decompression dives. The largest number to the left of the bold line is the NDL (in minutes) for that depth.

2. If the exact bottom time is not listed, use the

repetitive group (RG) for the next greater bottom time. Where no RG appears beside a particular bottom time, cease diving for at least 18 hours.

The NDL will be used later on to calculate the residual nitrogen time present in the tissue.

Fig. 8.4: A sample dive profile; according to the DCIEM table, the two DS’s are not necessary

Fig. 8.5: Table A

3. The ascent rate is 15 ± 3m/min. divers are advised to spend two minutes between 3m and 6 m while ascending from every NO-Decompression dive.

4. The section to the right of the bold vertical lines is

used for decompression dives, dives that exceed the NDL (fig. 8.5). Decompression stops must be conducted before surfacing from these dives. Decompression stops times are given in minutes.

Fig. 8.5: Table A (Deco Stops)

DCIEM Table B (fig. 8.5): 5. Match the RPG letter with the surface interval to

find the RF – a residual nitrogen indicator for a following dive is limited 2.0 and is the highest repetitive factor (RF).

6. As the surface interval (SI) increases, the RF

decreases. Any dive conducted when the RF is greater than 1.0 is a repetitive dive. If a RF is 1.0, use the 1st dive NDL (table A). If a RF is greater than 1.0, use the repetitive dive NDL’s (table C).

Fig. 8.5: Table B

7. Before conducting a repetitive dive, allow enough SI time to elapse for a repetitive factor to appear in table B. if an emergency forces you to dive before a RF appears, apply the following guidelines:

33m depth gives RPG = B and RF = 1.2 1st dive NDL = 12mins along with two safety stops at 6 and 3m (according to the table not necessary)

(a) for dives to the same depth: add the bottom times together and use the total time to determine your

RPG letter and decompression status. (b) For dives to different depths: take the RPG letter from your first dive and find the same letter group at

the second depth. Begin the 2nd dive as if you had already spent the bottom time listed beside the group letter.


DCIEM Table C (fig. 8.6): 8. The NDL for repetitive dives are given in table C.

The maximum depth of a repetitive dive must not exceed that of the preceding dive. (a) To find the NDL, match your RF with the

depth of the repetitive dive. (b) Find the RNT by subtracting the repetitive

dive No-D limit from the previous NDL for the same depth.

(c) On a repetitive dive, ABT is added to the residual nitrogen time (RNT).

The RNT from the first dive must be taken from Table A (highlighted #3).

Fig. 8.6: Table C 9. Add the actual bottom time (ABT) to the RNT.

The total of the ABT plus RNT is the Effective Bottom Time (EBT)

10. If the actual bottom time exceeds the NDL, a

decompression stop will be required. Stop times are given in table A according to the depth and EBT.

Dive #2: 27m depth with RF of 1.2 tmax of 2nd NDL dive (table A) = 20mins - time of 2nd rep. NDL (table B) = 14mins RNT of 2nd dive = 6mins

adding 12mins of the actual bottom time to the RNT results in an EBT of 18mins at 27m and RPG of D.

RNT of 2nd dive = 6mins + ABT of 2nd dive = 12mins EBT = 18mins

In order to find the remaining RPG and RF’s the calculation with the remaining two dives: the procedure provides the following results for dive #3: Finally, doing the same procedure for the last dive:

Dive #3: 21m depth with RF of 1.2 tmax of 3rd NDL dive (table A) = 35mins - time of 3rd rep. NDL (table B) = 25mins RNT = 10mins

adding 16mins of the actual bottom time to the RNT results in an EBT of 26mins at 21m and RPG of D

(as D was already used it will become E) RNT = 10mins + ABT of 3rd dive = 16mins EBT = 26mins

Repetitive Dives & Multi-day Diving (fig. 8.7a): 11. The RPG letter for each repetitive dive must be

greater than that of the preceding dive. Otherwise, add one letter to the RPG taken from the preceding dive and use the higher letter; i.e. when the 2nd dive resulted as RPG =D, the 3rd dive with the same RPG automatically becomes E; and so forth....

12. After three days of repetitive diving, a day off

from using SCUBA is recommended.

Dive #4: 12m depth with RF of 1.2 tmax of 4th NDL dive (table A) = 150mins - time of 4th rep. NDL (table B) = 125mins RNT = 25mins

adding 38mins of the actual bottom time to the RNT results in an EBT of 63mins at 12m and RPG of E

(as E was already used it will become F) RNT = 25mins + ABT of 4th dive = 38mins EBT = 63mins

Finding the Minimum Surface Interval (fig. 8.7b): 1. in table C, select the depth and find a NDL that

meets or exceeds the ABT. The RF required to conduct the dive is given at the top of the column; e.g. aiming at a depth of 15m gives a max No-decompression time limit of 41min and a RF of 1.5.

2. In table B, match this RF with the RPG letter from the preceding dive. The minimum surface interval is given at the top of the column; e.g. if the preceding dive yields a RPG E-diver, then a minimum surface interval of 1h is required to perform the dive at the aimed depth and duration.

Fig. 8.7a Table C and Fig. 8.7b: Table B


Depth Corrections in Altitude Diving: Any dive conducted at an altitude greater than 300m above sea level is considered an altitude dive. Depth corrections are necessary when diving at altitude because the reduced atmospheric pressure makes the altitude dive equivalent to a much deeper dive at sea level. Table D is used to convert the actual depth at altitude to an effective depth, which corresponds with the depth figures, intended for use at sea level (fig. 8.8). 1. Apply the following procedures only after having

acclimatized at the altitude of the dive site for at least 12 hours: (a) Establish the actual depth and altitude. (b) Find the depth correction by matching the

actual depth with the altitude. (c) Add the depth correction to the actual depth

to determine the effective depth – the equivalent sea level depth for an altitude dive. Apply the effective depth to table A (or to table C for repetitive dives);

(d) If the dive exceeds the NDL, decompress at the actual deco stop depth given in table D!

Fig. 8.8: Table D

2. If one must dive before 12 hours have elapsed, begin with the next greater depth instead of the actual depth. In the example given, begin the procedure as if the actual depth was 21m, which results in an effective depth of 27m!

Omitted Decompression Stop: Divers who have missed DS are to remain out of the water, rest, breathe 100% O2, drink plenty of fluids, be monitored for signs and symptoms of DCI / DCS, and be transported to a hyperbaric facility if symptoms are suspected.

Altitude: 1800m with a bottom time of 35mins actual depth = 18m + depth correction = 6m effective depth = 24m

according to table A: stop time is 10mins at 3m actual decompression stop at altitude is 2.5m!

Flying after Diving: Reducing ambient pressure below that of sea level by ascending with an aircraft after diving can produce DCI / DCS. There should be at least a surface interval of 12 hours after a single dive before flying. In case of multiple day diving over several days, the minimal required surface interval should be 24 hours. Dive Computer Theory and Application Dive computers differ from most traditional dive tables in that they track the pattern, rather than the square-shaped profile assumed by tables (fig. 8.9). Actual profiles look rather like multi-level dives that fall short of a squared profile, so extending the available time underwater. The wide variety of dive computers on the

Fig. 8.9: Actual and fictive dive profiles

market can give a large range of decompression data for similar dive profiles, and it is up to the diver to decide which is the best for its purposes. American Academy of Underwater Sciences (AAUS) has established guidelines for the use of dive computers; • Each diver relying on a dive computer must have her / his own device; • In buddy pairs, the most conservative dive computer determines dive planing; • If both dive computers fail (buddy pair), the dive must be aborted and re-surfacing procedures initiated; • After powering up a dive computer, there should be at least a waiting period of 18 hours; • Once in use, a computer shouldn’t be switched off until indicating complete degassing, or 18h have elapsed • Ascent rates given by the dive computer should be followed; • Ascent rates should never increase 15m/min; • On every dive – even on shallow ones, as well as using the computer – safety stops should be made; • Repetitive dives should follow according to the “DEEPER DIVE FIRST” maxim; Aids to Decompression The most common aids available for obtaining information about decompression are the dive tables and the dive computer. None of them however, can make decisions for the diver. The diver has to decide how deep a dive should go and how long it is to stay at that depth.


9. Rescue The “Zero Accident” Goal Incident vs. Accident: Diving incidents are unforeseen events with minor or casual significant results that can happen at any time with no apparent harm to a diver (no physical manifestation). A dive accident on the other hand, is a mishap causing injury or even death, and requiring medical assistance, and or some sort of medication. The zero accident goal is a strategy that involves careful observation and analysis of pre-dive arrangement, on-site safety measures , briefing, supervision, and post dive analysis of the events. Leadership Issues: dive leaders who organize and supervise have a concept of duty; this is expressed as the reasonable obligation to provide aid on the part of a diving leader and reasonable expectation of that aid on the part of a supervised diver (can be an issue of debate); e.g. the dive leader must have a checklist ready of what sort of tools and kits to take for a particular dive. The Right Response: not all diving incidents can be solved easily or quickly. The response process should involve a brief pause of reflection (thinking precedes action and the amount of action is dictated by the “least amount necessary” rule). No one has the duty to respond to anyone’s difficulties in the water, but if one decides to respond, remember: don’t leave the person in a state worse than you found her / him before your assistance. Accident Management: pre-dive arrangements include routine emergency protocols; a dive leader / coordinator, should have all the necessary emergency equipment and contact details available (see end of Chapter 9 Accident Management).

Fig. 9.1: Being prepared for an emergency

Be prepared: by knowing what to do, any member of the crew will be able to assist in an emergency. The following list provides a baseline (fig. 9.1): i) Keep information about the diving crew in a handy place; i) keep medical and insurance records (DAN) up-to-date; i) find out if the community in which the dive takes place has the international emergency access number (122);

check front pages of the local phone directory and inform everyone in the briefing about these numbers; i) keep emergency telephone numbers in a handy place, such as the 1st aid kit, including home numbers, family

members, and friends – be sure to keep both lists current; i) always bring a 1st aid kit along; i) practice 1st aid skills regularly and attend annual refresher course; i) divers suffering from particular abnormalities should wear their medical alert tag; The most important things are to recognize that an emergency has occurred and to call the local emergency telephone number. Then give 1st aid until help arrives. Pre-Emergency Signs Critical Incident Stress: facing something unknown always poses some sort of stress. There are two main methods to reduce stress of this kind: i) formal: try to get your buddy and yourself under

control; i) informal: try to play it down; not allowing to let

someone be affected by some sort of trouble, dispute, etc.

Unchecked critical incident stress: any incident not analyzed or identified if not on the spot, eventually later on will lead to an accident.

Fig. 9.2: A phase model of events of stress events and

responses According to the phase model of stress events displayed in figure 9.2, challenges can be perceived as being either positive (eustress) or negative (distress). Challenges with which we can cope are invigorating, whereas challenges beyond our coping abilities, tax biological systems and create distress, anxiety, and depression. Stress is the condition the body response to stimulation. The body tries to adapt to the stimulation, so, secretion of hormones affect the body’s defensive structure (autonomic nervous system and immune system). The “di-“ and the “eu-“ refer to the stressor, and not to the impact of the stressor (a stimulating, challenging dive vs. task overload resulting in mistakes). In either case, both can be equally taxing to the body and are cumulative in nature.


Stress - Chain of events Recognizing Excessive Stress: determine if you are under excessive stress; simply ask yourself if you are eager to make the dive at hand, and then, of course, to answer the question honestly. Keep asking yourself if feeling anxious, if under stress, if there are troubles with something; are you happy with the dive that’s about to occur? Because once the stress cycle gets going, the adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) which make the heart rate to go up, boost blood sugar levels, increase breathing rate, and shunting off blood supply to the digestive tract providing more blood supply and sugar to the muscles (fig. 9.3). Cortisol released from the medulla accelerates sugar metabolism, thus preparing the diver for a stress response. Feelings that are generated by excessive stress include strong misgivings and the inability to act! Therefore, meet the divers separately before you go to a dive; in this way one can best differentiate normal behaviour and evaluate it properly (e.g. introvert behaviour prior to dive).

Fig. 9.3: Stress response

Personal Stress Management: the best way to remove negative stress is by feeling competent and confident about one’s ability based on a frank assessment of the level of fitness, diving knowledge, and well-practiced skills. If stress does start to build up before a dive, recognize and deal with it immediately and effectively. Talk openly and address it, doing so avoids putting yourself and others at risk. Stress Related Behaviours: include gear-fumbling, blabbering, behavioural extremes, or even obsessive behaviour ....; all these are indicators that perceptual narrowing to the exclusion of every thing else is taking place. Helping a “Stressed-out” Buddy: if one’s buddy shows signs of stress one must deal with it before diving or make someone in charge aware of the fact that a new buddy is needed, and that the reason for such a decision is that one believes the person being rejecting may be unfit to make the dive. LEARN to LISTEN! Signs of Distress: when stress becomes distress it requires immediate rescue or harm will result. Distress is obvious and observable. Passive distress goes even further in that the victim accepts their fate and slips quietly beneath the surface for the 3rd and the last time. Underwater Signs of Distress / Impending Problems: a distressed diving person breathes faster and uncontrollable (generating heaps of bubbles), keeps sinking and rising (buoyancy problems), generates erratic, jerky movements, has troubles to trim properly, and keeps rejecting gear vigorously. Overcoming Fear: fear is a natural consequence when facing an unexpected event. By maintaining the focus on the goal, it is possible to control a situation and avoid the occurrence of a series of such events that ultimately increases stress. Usually the combination of several stress factors most certainly pushes the affected diver into the PANIC PIT (fig. 9.4). Panic is the cause of most diving fatalities. In some cases the unkindness of strangers or buddies accounts for increased stress levels. In a rescue event a nasty buddy is a major problem, while bystanders during a 1st aid assistance can become quite annoying; shouting and screaming like: “no that’s wrong!”

Fig. 9.4: The panic pit - once at the bottom of the pit

the diver will definitely shoot out of the water

Dealing with “Out of Air” Situations Prevention is everything: regularly monitor your tank pressure and your air consumption rate. If this does not happen, then the other diver(s) involved should assess the situation, and act accordingly. Only if the outcome is considered an emergency requiring an immediate abortion of the dive, then a decision to go to the surface by oneself (independent ascent) or along with the assistance of the buddy (dependant ascent) should be made. For the sake of safety and protection of anyone involved a controlled dependent ascent should be made. Mutual emergency planning: all effective buddy briefing must include the emergency plans and the type of equipment chosen (part of risk assessment)!


Self-rescue for an out-of-air emergency: only loss of buddy contact and no spare-air supply justifies an emergency ascent. Alternate Air Source (AAS): it consists of a small cylinder with a built in regulator (fig. 9.5). Usually it provides enough air to make an emergency ascent unnecessary but allows a normal resurfacing procedure with a built in safety stop. There is no “correct location” where it should be placed, but it definitely should not be stored in the BCD pocket!

Fig. 9.5: Spare air bottle

Emergency swimming ascent (ESA): when faced with a problem, first stop, think, and then act. Often an incident can be solved on the spot. If though, an out-of-air situation is imminent and the buddy is not around, then an emergency ascent should be done. To avoid life-threatening consequences afterwards, it is an absolute MUST to exhale continuously while doing an emergency ascent from 10-15m deep (fig. 9.6b). To avoid bolting to the surface, it is essential to deflate the BCD gradually while going up. While executing an ESA, rather then removing the mouthpiece, it should stay in place, as extra air might become available as the diver reaches shallower depths. ESA is acceptable for shallow water dives. After having reached the surface, the diver must STOP diving for at least 24h.

Fig. 9.6a & b: Diver ditching his weight belt properly (left) and right: Emergency swimming ascent (ESA)

BCD Breathing Ascent (BBA): the air contained in the BCD is breathable (provided it has not been inflated with a CO2 source). By removing the mouthpiece, placing the inflator mouthpiece into the mouth, and blowing into the inflator hose removes trapped water (by pressing the valve open); gradually roll over into a back-down-belly-up position to increase the air-pressure exerted to the inflator mouthpiece. Breathing continuously (out of the nose) while making the ascent avoids lung barotraumas. It should be mentioned though that bacteria and fungi present in the BCD might find their way into the lungs when executing BCD breathing. BBA is appropriate for deeper depth dives. Alternate 2nd stage air sharing (ASAAS): providing the out-of-air diver with the spare regulator (2nd stage with extended hose), both divers have to make sure that they hold firmly onto each other. The concept of buddy pairs makes a controlled ascent possible, as long as an ascent rate of about 15m/min is maintained. Shared Air Ascents (SAA) if a spare regulator is not available, buddy breathing must be executed by sharing the working air-source and regulator. Both divers must face and firmly hold onto each other (fig. 9.7). While one takes a deep breath, the other slowly exhales through the mouth. As soon as the breathing cycle is established, a controlled ascent should begin. It should be kept in mind that saliva can be a mediator for the transmission of any form of Hepatitis.

Fig. 9.7: Shared air ascent (SAA); a firm grip is

essential for a safe SSA Problems with air sharing: to avoid that one is dragged away, practice eye contact and use them as “a mirror” of to monitor the situation (remember, always repeat emergency commands prior to any dive). Both ASAAS and SAA are appropriate for deeper depth dives.


Rescue and Rescue Techniques Any incident or accident that requires assistance by somebody else to come safely to the surface is known as a rescue. This implies that assistance occurs in a way without putting yourself in danger or excess risk of requiring assistance yourself (remember Noel’s story with the 177m dive that almost ended in tragedy due to near blackouting while ascending). Preventing dive incidents start already with little things like a working onboard radio, readily available dive flags, assigning a lookout person, a properly fitted 1st aid kit, etc. Self Rescue: The first step in reducing the risk of diving and preventing diving accidents include rescue plans that are pre-established prior to the dive; properly maintained and familiar equipment; should ever happen something, then some sort of self rescue skills like STOP! Breathe, THINK , Breath, and then ACT can reduce the likelihood of an adverse outcome. One’s own best buddy is oneself; therefore at the 1st hint of doubt, simply drop your ballast. Don’t save on material things if your life is in danger – tools and gear can be substituted, one’s health instead not! Assisting Another Diver: one of the most common “rescues” involves the assistance of exhausted divers due to lack of fitness and or improper training. Remember, snorkelling is the best pre-dive training, but never exceed your training (don’t exaggerate and be aware of shallow water blackout). Underwater Rescue – Is it safe to intervene? Responsibility vs. Duty: along with the privileges of a being SSD comes some pre-arranged, documented assumed burden of duty with another diver or divers; such as when acting in a well-defined position as a diving leader, you have no responsibility to risk yourself for another diver; contacting emergency services to obtain assistance ASAP. Risk Assessment: under no circumstances should the rescuing diver / team exposing then to excess risk. All rescues begin with the difficult question like “is it safe for me to respond” (are there any imminent dangers when assisting) along with the logical follow-up “where is the buddy?” Ask yourself if it is safe to intervene: “Am I willing to assume the risk that intervention represents?” Often it is best to wait until the panic attack has passed from an agitated state to a state of acceptance of faith before intervening. In fact, it is up to the situation in which this “split-second decision” has to be made. Having made a decision in favour of rescue, a series of actions have to be taken immediately. With a non-responding diver, the 1st one involves how to lift the unconscious to the surface (usually by unclipping the weight belt and gradually inflating his/her BCD without removing the regulator of the victim’s mouth). Once back on the surface, it is followed by the 2nd task of checking for vital signs (ABC - check airways, breathing and circulation) followed by the 3rd and most crucial part of getting the victim out of the water. Effecting Rescue: a scenario for an unconscious victim: • Get the victim to the surface. • Establish positive buoyancy. • Stabilize breathing or begin and maintain appropriate life support. • Remove the victim and the rescuer(s) from the water. • Provide an appropriate 1st aid in consideration of the victim’s needs and available medical system (enough

O2 should be there to bridge the window until emergency crew is present). • Transport and / or maintain the victim until relieved by more qualified personnel.

Warning Sings of Impending Panic: seeing a diver struggling underwater, is an early stage of an imminent situation of stress. Accumulation of such incidents in a short period of time drives the stressed diver into the panic pit. In order to relief the stressed diver, approach him ASAP and lend assistance. Sings of distress include: • Shallow and rapid breathing (continuous bubble trail). • Upright position with “dog-paddling” hand and arm movements as well as pumping knee action. • Quickly, jerky, fumbling movements, • Wide, fright-filled eyes, • Mouthpiece abandonment, • Bolting to the surface, • Self-centered, attention focused on how to get out of the water, • No response to signals, • Choking and eventually, and • No signs of breathing.


Underwater Panic: panic can strike any diver (fig. 9.8). When a panicking diver underwater is about to bolt to the surface, they usually hold their breath, which in most cases result in lung-barotrauma. To make such a diver exhales; kick them into the side (rib-cage). Monitoring a Panicked Diver: a panicked diver tries to get out of the water under all circumstances; there is little if anything a rescuer can do to prevent a panicked diver to bolt to the surface. Underwater Attack: when being attacked by a panicking diver, it is essential to take whatever means to break free from the offender. Swinging the arms from below to above, kicking with feet often helps to obtain a safe distance from that person.

Fig. 9.8: Underwater panic attack

An Unresponsive Victim: an unresponsive diver will drown without immediate assistance (fig. 9.9). The victim must be conveyed to the surface as soon as possible. Steps to be taken include: • Survey and monitor the situation and be prepared

to intervene. • Approach and establish positive buoyancy to the

victim by inflating the BCD. If there is no air left in the BCD, remove ballast (weight belt).

• Mouthpiece: hold the victim’s regulator in the mouth.

• Ascend, an unconscious diver is relaxed, expanding air will escape from the lungs (paying attention that ascent rate is such that it minimizes risk of injury to rescuer).

• To maintain surface buoyancy remove all extra gear that is not necessary, inflate BCD if not yet inflated.

Fig. 9.9: Surfacing an unconscious diver

Surface Rescue Observable Surface Problems: a person in distress at the surface is in obvious, easily recognizable trouble: • Treading high in the water with no air in the BDC. • Abandonment of mask and mouthpiece (evtl. hands splashing against the water surface, seldom they call out

for help or signal for assistance). • Continuously over-filling BCD (dump valve’s over-pressure system continuously releases excess air). • Lack or response to signals or verbal communications. • Chin barely above water and gasping. • Choking and coughing and eventually • Diver face down with no signs of breathing. If the diver in distress is responsive to verbal communication, the 1st task of the rescuer should be a shouting message: DROP BALLAST – INFLATE BCD!


If the distressed diver is struggling on the surface, then the following should be done: • Assessing Risk: act accordingly by judging each

situation separately as well as the victim. Leaving a panicked diver there until accepting the faith is often safer for the rescuer than assisting immediately.

• The Approach: Planning determines success. Sneak towards a panicked diver rather than signalling that rescue is coming by facing the victim. Remove ballast (weight belt), if there is no air left in the BCD. Unclip BCD, remove mask and snorkel, push, pull, victim to the shore or boat.

• Surface Rescue Priorities: ensure victim’s buoyancy (don’t over-inflate BCD as this may interfere with EAR), bring into vertical position, and ensure that victim is breathing.

Fig. 9.10: Escape from a panicking diver

Dealing with Panic at the Surface: a panicked diver is characterized by a total loss of logic and mental control. Thus, any attempt to rescue a panicked poses a serious risk for the rescuer. In most cases it is safer to leave the panicked diver struggling till to the point when the person is willing to accept her/his situation. If the decision is made to assist while the panic attack is still evident, the rescuer should sneak towards a panicked diver rather than signalling that rescue is coming by facing the victim. The panicking diver must be approached from behind or better from below. Then the tank valve and clamping the tank between the rescuers knees keeps the panicked diver from attacking the rescuer (fig. 9.11). Doing so ensures a safety distance in case the panicking diver starts to beat aggressively around. It will take a while until the panicked diver will find back into a more rational state of mind. Then, it is safe to remove ballast (weight belt), and/or inflate the BCD to obtain extra positive buoyancy. Escape from a panicking Diver: if assisting, and the salvage operation seem to take a bad turn, make sure drastic measures are applied, in order to guarantee the rescuer safety. People in panic-mode develop enormous strength and will try to step on top of you just to stay above water! Defence from a panicking Diver: drastic action must be taken in order to free oneself from a diver in panic mode. Swinging the arms from below to above (to break free from the grip), and kicking with feet helps to obtain a safe distance from that person.

Fig. 911: Getting hold of a panicked diver: grab the tank valve and clamp the tank between the knees

In-Water Respiration If an unconscious diver has been brought to the surface, then the paramount concern is to stabilize the victim, check breathing, and if necessary provide EAR. In order to do so, the victim should be grabbed by the DO-SI-DO technique (from above, reach under the arm of the victim and grab the tank valve, BC, or exposure suit). EAR is then given by providing a breath every 4th second (look, listen, feel, breath). Upon arrival to the shore / boat gradually proceed with equipment removal (including own), while continuing to provide EAR (see next page). Towing: towing or assisting in injured or tired diver is best done by dragging the victim along whilst holding firmly onto the tank valve (fig. 9.12). Other towing techniques are wheelbarrow push; here the breathing unconscious victim is lying flat on the water surface while the assisting diver pushes the victim with the feet held firmly against the shoulders toward shore or boat.

Fig. 9.12: Surface rescue – diver tow


Mouth to Mouth Rescue Breathing: effective rescue breathing as shown in fig. 9.13, requires that:

i) airways must be clear i) check and / or remove dentures i) control victim i) provide 15 ventilations per min by pinching the victim’s nose and administering a normal exhalation (approx. 0.5L) to the unconscious diver.

Mouth to Snorkel Rescue Breathing: is a method to keep water away from reentering the victim’s mouth. Pocket Mask Rescue Breathing: is an excellent alternative for rescue breathing and should be always be stored in one of the pockets of a SSD’s BCD. The pocket mask is placed onto the unconscious victim, sealing mouth and nose, and held in place with the elastic strap.

Fig. 9.13: Providing EAR with a pocket mask to a

diver in need Equipment Considerations: once EAR can be given on a continuos pattern, the rescuer can start to remove the victim’s gear; weight belt, snorkel, mask, fins, and BCD of the unconscious diver, while performing EAR. It helps to repeat a mental algorithm like LOOK, LISTEN, FEEL, BREATHE, to maintain continuous EAR. Once the victim is stripped of gear, the rescuer can do likewise (except for fins) until shore or boat is reached. If CPR is necessary, it can’t be performed effectively in the water, the paramount concern is to get the victim rapidly to solid ground (see Chapter 10 1st Aid - Resuscitation). Administer pure O2 to increase efficiency of EAR. Assessing Problem: the best way to learn what may be wrong is to observe and ask (if possible). A rational answer is OK, while an irrational answer should be a sign of alarm. When bringing an unconscious diver aboard / ashore and professional medical help is not yet available, you are the most qualified person to handle the situation, manage the accident. Auxiliary Surface Rescue Aids: boats, paddlecraft, personal water craft (dive boat, fig. 9.14). Removing a Victim from the Water: while the victim is still horizontally positioned in the water, the rescuer positions her/himself that the chest is facing the victim’s head. From behind, reach under the victim’s armpits to grab the victim’s left or the right arm. Then the rescuer walks backwards gradually out of the water. If another diver can assist, then they should hold each other’s arm to provide back-support while dragging the victim out of the water. Terrain issues can sometimes interfere with a smooth rescue operation. This should be taken into account prior to the dive! Lifting an injured diver onto a boat is best done by placing the victim into a barge and hauling it aboard along with the victim (rather than dragging them over the edge).

Fig. 9.14: Recovering an unconscious diver

Fig. 9.15: Parbuckling aboard

Fig. 9.16: Hauling an un/conscious diver onto the beach

Parbuckling: Parbuckling involves the use of a sledge, planks, ropes and blocks and tackles (fig. 9.15). Carries and Lifts: are shown above; the victim is either dragged or with the help of another aider lifted ashore (fig. 9.16).


Accident Management Emergency Planning must be done before the dive and this involves the following: • communications equipment: like on board VHF radio with DSC function, mobile phone, etc. along with

emergency numbers (DAN, or hyperbaric chamber facilities, etc). • emergency equipment as discussed (1st aid kit, O2-delivery systems, etc.) • trained personnel: at least the dive coordinator, or dive leader should be trained in 1st aid and O2-supply. • emergency management: make sure that the group stays together and does the following:

i) Assess (what has happened, what must be done) i) Appoint (who does what; i.e. call medical assistance, keep time log of all activities taken, to collect

victim’s medical history or medical alert information, witnesses. i) Account (made for all divers involved in diving activities) ???? i) Act (start rescue operation); locate victim, bring ashore / aboard, and continuously monitor vital signs, or

if conscious, provide assistance and perform rapid neuro-exam. A good way to remember the procedure when not having the full rapid exam protocol by hand is to use the acronym COWS as a tool for rapid assessment (can you hear me, open your eyes, what’s your name, squeeze my hands).

One note: secure victim’s equipment; leaving the 2nd stage mounted onto the 1st stage together with the tank. Equipment must remain “as is” until released by authorities – DON’T disassemble! Evacuation Procedures: assisting the diver during evacuation, transport and transfer. Make sure that the victim is placed properly to make transfer easier (bucket-like seater). Have proper means available (even improvised) to avoid further damage while relocating towards emergency facilities. Boat to dock or boat to shore transfer: avoid damage to yourself (muscle strains) during assistance, rather use lifting tools. Air evacuation: if it is necessary to evacuate victim via helicopter, make sure that you “advice” (don’t tell) the crew upon notification that they have O2-supply aboard and will not exceed 300m altitudes while evacuating the victim to proper medical facilities (fig. 9.17). N.B.: Airlift from a vessel or the water: never touch the ladder hanging down from a helicopter until it has touched the ground – electrostatic charge can result in serious injuries!

Fig. 9.17: sea rescue by helicopter


10. First Aid and the Chain of Survival in Diving A ccidents The main objects of the Occupational, Health and Safety Act are:

(i) to secure safety and welfare of persons at work; (i) protect persons against risks to health and safety; (i) to assist in securing safe and healthy work environments; (i) to eliminate at the source any risk to health, safety and welfare of persons at work; (i) and to provide for the involvement of employees and employers in the formulation and

implementation of health and safety standards. The purposes of Codes of Practice in the workplace provide employers and employees with practical guidelines to assist them in complying with legislation. It generally includes 1st aid training requirements, 1st aid equipment requirements, 1st aider requirements. The duties of an occupational 1st aider are provision of 1st aid, maintenance of 1st aid kits and facilities, identification of hazards, maintenance of records, education and counselling on health and safety issues. When accidents occur and 1st aid is administered the following information is required when completing a workplace “Injury, Illness & Incident Report” form21: name, address, and telephone number, age and sex of victim; date, time, and location of incident; history of the incident; 1st aider’s assessment; observation such as response, respiration, pulse taken at regular intervals; observed injuries; full details of 1st aid provided; any referrals advised such as own doctor, hospital, ambulance and whether this should be sought immediately or later if problems persist / arise22. The completed form must be handed over to the Occupational Health and Safety Officer at the University. Legal issues in 1st aid The principle aim of 1st aid is to preserve life, prevent further injury, protect the unconscious, promote recovery, access medical aid. The 1st aider is not always obliged to assist an injured or ill person; assistance should be provided only when duty of care is owed. Once the 1st aider decides to act, s/he must make sure that the chain of survival is maintained. The Chain of Survival Any emergency medical systems (EMS) around the globe are included in a network of community resources and are on permanent standby (fig. 10.1). Upon receiving an emergency call (via marine radio, mobile phone, satellite, landline, etc.), precious time will elapse between the actual time of arrival of the paramedics. It is this time the 1st aider must use to assess, monitor, stabilize, or eventually even provide vital life support in form of EAR / CPR to increase the chances of survival of the injured person. In order to do so, the 1st aider must act: i) move only if the victim’s life is endangered; i) ask a conscious victim for permission before giving

care (if consent is not given, a person could take legal action for assault);

i) summon professional help to the scene by calling the local emergency number;

i) continue care until trained personnel arrives. Even though a 1st aider may be at risk of legal action for providing assistance, legal action is unlikely if 1st aid is provided within the level of training and experience of the 1st aider. But remember, do not cause harm, and never leave the victim in a worse state than it was prior to assistance.

Fig. 10.1: Chain of survival

Fig. 10.2: The 1st Aid kit

21 http://www.uq.edu.au/ohs/pdf/accida.pdf 22 see Appendix Workplace Injury Form


Risk of cross-infections The most significant body fluid of concern to emergency care providers is exposure to blood. To minimize direct contact with blood, disposable gloves, eye protection, resuscitation mask, towels, etc. should be placed in every 1st aid kit (fig. 10.2). This in order to protect oneself as well as the victim from infections and transmittable diseases (mostly hepatitis A to F). Usually hepatitis is only spread when a cut or a mucosal injury in the mouth is present. Victim assessment For the 1st aider it is useful to asses and record vital signs periodically. Doing so provides a baseline to determine if and how the victim’s condition is changing at any time. The usual range for the resting pulse rate of an adult is 60-80beats. Should hypoxic conditions (lack of O2) arise, the skin colour changes from a reddish hue to a bluish colour (cyanosis). This is a clear indication that there are troubles in supplying oxygenated blood to vital target tissues. If countermeasures are not taken immediately the victim becomes unconscious and ultimately if still no action is taken will die. The 6 main causes of unconsciousness include hypoxia, drug overdose, head injury, toxic gas inhalation, epilepsy, and diabetes, among others. When assessing an injured person, the 1st aider can use the acronym DABC as some sort of guidance; it stands for presence of dangers to the aider, followed by checking the victim’s airways, breathing, and circulation (fig. 10.3). To enhance this procedure, a 2ndary survey should be performed; it involves a visual and tactile examination of the entire body. It is designed to help a 1st aider to determine what injuries are present, and if possible is conducted once the primary survey (checking for vital signs) is completed and acted upon. There’s one thing the 1st aider should keep in mind: to differ between signs and symptoms; a sign is something a 1st aider observes on the victim; a symptom on the other hand is something the victim feels. This discrimination must be strictly followed to make sure that 1st aid remains 1st aid and will not become therapy! (this is not the duty of a 1st aider as this goes far beyond the skills and scope of an emergency care provider). Resuscitation It is important to commence resuscitation ASAP. Death of brain cells usually begins after about 3-5mins of O2 deprivation. Before resuscitation can begin, the airways must be checked and cleared; the preferred method to open the airway of an adult is to apply a head-tilt and chin-lift, or jaw-thrust. If an unconscious victim left lying on the back it is important to support the lower jaw; the tongue, which is attached to the lower jaw, will fall against the back of the throat and block the airway. Then the unconscious, (maybe) breathing victim must be positioned on the side. In case of vomiting the lateral position allows drainage of fluids, and help to keep the airways open.

Fig. 10.3: What to do in an emergency


Expired Air Resuscitation (EAR): this methods works because exhaled air still contains about 16.5% O2, about 4% CO2, and 0.5% H2O vapour. This O2 concentration is sufficient to maintain conscious and adequate oxygenation of the brain for a limited period. If the victim is NOT BREATHING, the victim must be rolled back; then the 1st aider should ventilate just enough to cause the lower chest and abdomen to rise – ONE BREATH every 4th SECOND (fig. 10.4). This reduces the chance of stomach inflation and may assist gas exchange which occurs more during the expiration phase in resuscitation. Blowing too hard, not allowing the chest to fall between ventilations, inadequately open or clear airways, increases pressure on the stomach (gas enters the stomach) and regurgitation may be the result (= the passive outflow of stomach contents; not be confused with vomiting, which is accompanied by active muscular spasm). If the victim regurgitates during EAR, s/he must be placed on side, clear airways, reposition on back, reassess technique and correct where necessary. Successful EAR is achieved when chest / abdomen movement is observable, maintenance of spontaneous pulse (although very unlikely), resumption of breathing, sometimes improvement of the colour of the victim’s tongue, lips, and skin. Abdominal Thrusts (Heimlich maneuvre, fig. 10.5) is designed to clear the airways of obstructing objects. Applying a quick upward thrust that causes sudden elevation of the diaphragm and forceful, rapid expulsion of air in the lungs. This action forces air out of the trachea to eject the object obstructing it. It is also used to expel water from the lungs of near drowning victims before resuscitation is begun. In an unconscious victim it is best done by laying the victim on the back, positioning oneself over the victim’s legs, straightening the arms, placing the heels of the hands just above the navel with the fingers pointing towards the victim’s head and give quick upward pumping motion against the stomach.

Fig. 10.4: Administering EAR – continue breathing as long as pulse is present but person is not breathing, or

until emergency crew is on site

Fig. 10.5a & b: Abdominal thrust: conscious victim (left) unconscious victim (right)


Cardio-Pulmonary Resuscitation (CPR): If the victim shows signs of cardiac arrest (no signs of breathing or circulation) CPR must be performed. aid. A defibrillator should be on site (at least on the boat) - learn to operate it23. Remember to check battery function regularly to make sure it will work in an emergency. Events in the past have shown that cold water drowning victims are usually predisposed candidates for CPR if: i) immersion has not exceeded 60mins (in teenagers or

kids younger than 10yrs of age); usually once a 3-4min period has elapsed without CPR, it is almost impossible to avoid brain damage due to lack of O2;

i) there is no other lethal injury present; i) the procedure will not put rescuers unduly at risk. Finally, the CPR-victim will not unduly delay necessity of re-warming (via body heat). The use of kneepads can relief pain while providing 1st aid

Fig. 10.6: Administering CPR - continue with CPR

until emergency crew is on site

Performing CPR: is the artificial establishment of normal or near-normal respiration and circulation. The ABC’s of CPR are clear airways, check breathing, and circulation (fig. 10.6). Assessing the need by pulse determination (can be quite difficult in hypothermic victims). Never provide CPR while heart is still working - this would quickly stuff it up! Ingested water usually makes the victim vomit; if this should happen roll the victim aside, clear the airways, and continue with EAR or CPR. Single rescuer: the ratios and rates for single-rescuer CPR on an adult are 2 BREATHs and 15 COMPRESSIONs in 4 cycles per minute. Monitor pulse after having performed at least 8 cycles in a row. This interruption should not take longer than 5-10 secs. Pair of rescuer: if two-rescuer CPR on the adult victim can be performed, then 1 BREATH and 5 COMPRESSIONs in 12 cycles per minute must be administered. The chest-abdomen movement, maintenance of victim’s pulse, return of breathing, sometimes improvements of colour of victim’s lips and skin are indicators to monitor the effectiveness of EAR. Effective CPR is achieved when the presence of an artificial pulse can be detected (requires a 2nd rescuer), possibly improvement in the colour of the victim’s skin, lips, and tongue. It is quite unlikely that CPR will return a spontaneous pulse unless a defibrillator is at hand; therefore, keep working on the victim until professional help is at site!

23 http://www.m-ww.de/enzyklopaedie/diagnosen_therapien/defibrillator.html


Other emergencies a 1st aider should be able to deal with include: Breathing emergencies - Asthma Less dramatic events but likewise disturbing as they require immediate assistance, are breathing difficulties; e.g. an asthma attack. The mechanism of an asthma attack is an inflammation and swelling of mucosal lining of the small airways, secretion of mucus, and broncho-spasm. An asthma attack can be induced by an allergic reaction, exercise, cold weather, nervous tension, upper respiratory infection, etc. The symptoms of asthma attack are cough, rapid / difficulty breathing, wheeze, pallor, distress, , exhaustion, altered conscious state, inability to speak, and even cyanosis (turning bluish). The 1st aid management for asthma is reassurance, position of comfort, if the victim possesses its own emergency broncho-dilator, aid in the administration, medical aid as appropriate (the patients own medication!), O2-therapy if available. Cardiac emergencies Coronary arteries deliver the heart with oxygenated blood. Narrowing of the coronary arteries (ischemia) occur especially with advanced age, diet, unhealthy lifestyle, smoking, and / or hereditary factors. Usually myocardial ischemia causes hypoxia and results in a condition often termed Angina pectoris. It is a tight or squeezing sensation of the chest along with chest pain, or discomfort and / breathlessness arising from inadequate perfusion of the heart muscle (myocardium) as a result of exertion or stress. These symptoms usually abate with rest and / or medication. Should critically narrowing or complete blockage of the coronary arteries occur, the term heart attack (myocardial infarction) is appropriate; it is the results of a thrombus (stationary blood cloth) or embolus (blood cloth transported by the blood). The tissue beyond obstruction experiences inadequate perfusion, eventually dies and is replaced by non-contractile scar tissue. Signs and symptoms include chest pain or discomfort which may radiate to the neck, shoulders, jaw and arms; breathlessness; nausea; pale, cold, sweaty skin; anxiety. Infarction may also result in arterial fibrillation (a non-lethal fluttering pulse of 240-360 beats/min) or ventricular fibrillation with no pumping at all, thus lethal if left untreated (fig. 10.7). Steps in the 1st aid for heart attack require urgent medical assistance; conduct primary survey and act accordingly; if victim is conscious, position of comfort, rest and reassurance, assistance with person’s own medication, supplementary O2 should be administered along with constant monitoring. Perform CPR if no pulse is detectable (see there).

Fig. 10.7: defibrillation of a victim

Shock and anaphylaxis Shock results in an inadequate O2-supply to vital organs. As part of the fight & flight response, and pooling of the blood in the legs, the body reacts by reducing the circulation to peripheral tissues such as the skin and limbs, and increasing the breathing and heart rates to maintain blood supply to vital organs, leaving the victim almost paralysed and unable to stand on its own feet (fig. 10.8). The most common signs and symptoms of a state of shock are a pale (bluish), cold, clammy skin; rapid, weak pulse; rapid shallow breathing (low blood pressure and lower pO2 in the blood boost hart and breathing rate); altered state of consciousness; weaknesses (blood drained from brain and extremities); nausea, thirst, and feels cold (reduced skin circulation). The 1st treatment for shock includes a primary survey, determining the cause, and act to rectify it where possible, control any severe bleeding, lay victim down with leg raised, provide O2, arrange medical aid, keep victim still and reassured, and survey the victim’s vital signs. It is important to seek medical aid when treating a person for shock, as the victim may deteriorate rapidly (most 1st aiders lack adequate experience to determine whether further treatment will be required).

Fig. 10.8: Schock scan- ask Mr. Halter


Soft tissue injuries, and Haemorrhages (Bleeding) The average adult weighing 70kg circulates around 5-6L (70-80mL/kg body weight). Blood is a near liquid composed of plasma (carries sugar, nutritional compounds, and other nutrients) in which cells are suspended; red cells containing haemoglobin for O2 carriage; white cells for fighting infections; platelets for clothing. It is transported in veins and arteries. Veins are thin-walled, have one-way valves to prevent back-flow, and carry blood back to the heart. Arteries have thick, elastic walls and carry the oxygenated blood away from the heart by a pumping action. The blood pressure in arteries is higher than in the veins. Bleeding and the associated loss of total blood volume is more problematic in children than in adults. Because of the small body mass they have less blood, and the loss of blood that would cause little problem for an adult could prove catastrophic for a child. Arterial bleeding requires immediate assistance and is far more dramatic than venous bleeding. In arterial bleeding bright red blood spurting (rather than flowing) from a wound. To control such type of bleeding, direct pressure to the wound must be applied and elevating the injured part where possible. To control bleeding from a wound with an embedded object, the 1st aider must not remove the object, but apply pressure around the embedded object and elevate the injured part and arrange medical assistance. In the event of amputation, how is the severed part managed? It should be placed in a clean plastic bag or container which is then sealed and placed in ice or icy water and taken with the victim to the hospital. For open wounds, get a tetanus booster if the person has not had one in the last 10 years. How is a nose bleed controlled? Via squeezing the fleshy part of the nostrils (just below the bones) and sitting quietly with the head upright and slightly forward (don’t bend head back). Skin injuries are generally classified into 4 groups; these are abrasion, laceration, incision, avulsion, puncture, embedded object, or amputation (fig. 10.9). Note: Avoid spitting, sneezing, coughing, into the wound; also refrain from using cotton tips or any other medication (incl. disinfectant). The use of disinfectant is no longer considered a 1st aid treatment! A sufficiently bleeding wound “cleanses” itself. Only when cuts are not bleeding, a disinfectant should be used; e.g. coral cuts. Caring for a major open wound: avoid being slashed by blood; place a barrier between you and the victim’s blood (gloves, or covering the wound with a dressing or plastic wrap). The 1st aider must wash the hands

Fig. 10.9: Bleeding injuries

immediately after providing care (even when wearing gloves). Eating, drinking or touching one’s mouth, nose, or eyes must be avoided at all times. Likewise avoid touching any objects that have been contaminated with blood, as well as avoid handling any personal items, such as pen, combs, etc. while providing care. i) control bleeding by placing a clean covering, (sterile dressing) over the wound and applying pressure. i) elevate the injured area if the wound involves any fractures; i) apply a bandage snugly over the dressing; i) if the bleeding can’t be controlled, put pressure on nearby artery (pressure point) and seek immediate medical

attention or transport victim to a medical facility; After immediate care, keep the victim from getting chilled or overheated. Reassure and comfort the victim! Signal of internal bleeding are sometimes hard to detect but can be recognized by tender, swollen, bruised, or hard areas of the body, such as the abdomen; a rapid, weak pulse; skin that feels cool, moist, looks pale or bluish; vomiting or coughing up blood; excessive thirst; becoming confused, faint, drowsy, or even becomming unconscious;


Chest injuries The most common chest indication is a fractured rib. It usually comes along with pain which increases with movement or touch; bruising; distortion; difficulty breathing. The 1st aider should assist the victim into position of comfort. This is often sitting or semi-recumbent and with affected side slightly lowered. Support the injured area, provide O2 and seek medical aid. In the case of a pneumo-thorax (a collapsed lung), air enters the pleural space (fig. 10.10a & b), changing the interpleural pressure and causing the surrounding section of lungs to collapse making breathing difficult or in severe cases impossible. In such cases immediate EAR must be administered.

Fig. 10.10a & b: A puncture wound (caused by spear gun or bullet)that penetrates the chest cavity into the lung;

a special dressing with one loose corner keeps air from the wound when breathing in and allows air to escape when breathing out (in case of the spear gun, do not remove object!)

Dislocations, and fractures Ligament and tendon: the former is a flexible band of fibrous tissue holding joints together and connecting various bones and cartilages, while the latter is a fibrous band of tissue connecting muscle to bone. Contusion: a swelling and discoloration under the skin caused by trauma to the underlying blood vessels. Strain: a stretching or tearing of muscle or tendon (fig.10.11). Sprain: stretching or tearing of ligaments normally caused by the stretching of a joint beyond its normal range of movement (fig. 10.11). The 1st aid management for a sprain or strain involves supporting the injured area using a compression bandage; elevate the injured area for rest; only then cool the affected area using cold compress-ice pack for up to 10mins at a time, ensuring that the skin is not being overcooled. Dislocation: displacement of part of the body from its normal position, particularly a bone from its normal position in a joint. Fracture: traumatic injury to bone in which the continuity of the tissue of the bone is broken; it can be simple or closed, compound, or multiple (a type of complicated) fracture (fig. 10.11). Signs and symptoms of a fracture include pain, loss of movement, deformity, swelling, grating sound (crepitus), tenderness, and shock. Do not attempt to realign the broken parts! 1st aid management of a fracture or dislocation include a primary survey; keep victim still and quiet; arrange medical assistance; immobilize affected area and splint in a position of comfort; elevate immobilized limb if possible; treat for shock as required.

Fig. 10.11: Sprains, Strains, Dislocation and Fractures


Fig. 10.12: Bandaging in 1st aid care; fractures, strains, sprains, and other injuries of the musco-skeletal system

should be taken care of by supporting the affected area and leaving it at rest until professional treatment is available.

Head and spinal injuries The fractured skull is a trauma to the head and usually results in an altered conscious state; discharge of fluids from ears, nose or mouth; bruising around eyes or behind ears; blood-shot eyes. The 1st aider should perform a primary survey, arrange urgent medical aid, keep victim still and quiet, and monitor closely for deterioration of conscious state and provide oxygen if possible. Concussion is the most common head injury; it is essentially the shaking of the brain resulting in temporary impairment in brain function. The signs and symptoms of concussion are loss of consciousness, headache, confusion, memory loss, nausea, vomiting, dizziness, and visual impairment. The 1st aid treatment aims at keeping the victim still and quiet, observe closely for deterioration of conscious state, and seek medical aid. What is often thought to be concussion could be in fact the early stages of cerebral compression. That’s why medical advice should always be sought in the event of suspected concussion. If any compression is not treated, the victim could deteriorate rapidly. Cerebral compression could prove to be fatal. Injuries to the spine can paralyse or kill. The spine is a strong flexible column of vertebrae that supports the head and trunk. The spinal cord runs through the centre of these bones. Nerves originating in the brain form branches extending to various parts of the body through small openings. Cerebral compression is a spinal injury and is a bleeding or swelling under the rigid skull can cause a fluid build-up, leading to the compression and subsequent damage of the areas of the brain. The signs and symptoms of cerebral compression range from loss of consciousness, headache, confusion, memory loss, nausea, vomiting, dizziness, visual impairment, numbness, tingling; paralysis, convulsions, unequal or slow pupil response, to respiratory distress.


Signals of head and spine injuries: changes in consciousness; severe pain or pressure in the head, neck, or back; tingling or complete loss of movement of any body part; unusual bumps or depressions on the head or over the spine; blood or other fluids in the ears or nose; heavy external bleeding of the head, neck, or back; seizures; impaired breathing or vision as a result of injury; nausea and vomiting; persistent headache; loss of balance; bruising of the head, especially around the eyes and behind the ears; Spinal injuries most commonly occur in motor vehicle accident, diving accidents, falling objects that result in direct trauma to head and spine. The indications of spinal injury include the history of the incident e.g. any recent activity that can be held responsible for the pain or discomfort in neck or back, altered sensation (e.g. numbness or tingling), weakness or paralysis, irregular bumps along the spine, priapism in males. Any 1st aid given when suspected spine injury, should be limited to seeking urgent medical assistance, and to a primary survey; avoid any twisting or forward movement of the neck, carefully roll the unconscious victim over into a lateral position, and maintain normal body temperature.

Fig. 10.13a: Slipped Disk

Fig. 10.13b: Kinetic lifting to avoid the slip-disk

syndrome Diabetes Although diabetes is a reason why a person is excluded from any diving activity. Type I diabetes begins already in childhood. The person affected usually knows about it as it is part of her/his medical history. Type II diabetes affects adults and is the type of diabetes that can remain undetected if an annual medical check-up is not performed (SSDs have to undergo annual checkups). The pancreas is the organ responsible for insulin production. A hypoglycaemic person suffers from a low blood sugar level resulting of too much insulin being excreted (injected), by missing a meal, over-exertion, or infection (fig. 10.14). The most common signs and symptoms of hypoglycaemia are weakness; light-headedness; dizziness, confusion; may appear drunk; aggression; cold, pale, moist skin; rapid pulse; shallow breathing; altered conscious state. In a hyperglycaemic person, the blood sugar level is too high, and is the result of lack of insulin (prior of diagnosis of diabetes) or forgot to administer an insulin dose. The indications of hyperglycaemia range from drowsiness, blurred vision, numbness in legs, feet, and fingers, itching, thirst, breath has a fruity smell, to increased urine output, and even unconsciousness.

Fig. 10.14: Diabetes – sugar-insulin imbalances

1st aid in diabetics must be limited to hypoglycaemic conditions; if the victim is conscious and can take foods or fluids, administer sugar in form of a soft drink (sugared water). If the person does not feel better within 5mins, call the emergency services. In unconscious victims, do not administer anything but call for help immediately; position person lateral and monitor ABC.


Eye injuries A 1st aider dealing with an eye injury should keep victim still, never place any object into the eye, place sterile path over affected eye avoiding any pressure on the eye, discourage any movement of either eye (by covering both eyes) and seek medical advice. When dealing with a small foreign body in the eye, the 1st aider should flush the eye with clear water (prefer sterile saline) and seek medical aid if problem persists. Otherwise the aider should not attempt to remove the object, but rather place protective cover (e.g. polystyrene cup) taped over the eye avoiding any pressure on the eye, discourage movement of either eye and arrange urgent medical aid. 1st aid for a chemical injury into the eye require immediate flushing the injured eye with copious amount of fresh clean flowing water, ensuring that the contaminated outflow does not enter the other eye (fig. 10.15).

Fig. 10.15: Flush a chemical contamination to the eyes (skin) with cool running water for at least 20mins or

until the ambulance arrives

Epilepsy An uncoordinated electrical discharged within the brain is called a seizure or convulsion. The condition that can cause a seizure is epilepsy, hypoxia, head trauma, brain tumour, infection, high temperatures in young children. What is epilepsy? A chronic condition where a victim suffers more than an isolated seizure. Some signs of generalized tonic-clonic seizure include collapse, muscle spasm, cyanosis, and frothing from mouth. 1st aid for tonic-cloning convulsion aims to protect the victim from external dangers, and not to restrain or place any objects in victim’s mouth, but rather place victim in lateral position when fitting stops, conduct primary survey, and check for injuries that had been caused by the seizure, seek medical assistance as required. Stroke A stroke occurs if a blood vessel to the brain becomes blocked, or if it ruptures, reducing the blood supply to parts of the brain. Some sign and symptoms of stroke are speech impairment, weakness or paralysis on one or both sides of the body, drooping of the mouth, confusion, incontinence, unequal pupil size, altered conscious state, unconsciousness. Steps in the 1st aid management of a stroke should conduct a primary survey and act appropriately, seek medical assistance, provide oxygen if available, reassurance, place in a position of comfort, loosen any tight clothing, wipe away any saliva from mouth, lift non-responding limbs over to the healthy side (cosmetic), make sure victim does not cool off, and maintain the victim’s respectability! If necessary, treat for shock.


Malaise and injuries predominantly related to SCUBA diving SCUBA and Rebreather divers breathe compressed gas. As discussed in previous sections of this course paper, this can lead to several unique problems (see Chapter 6 - Diving Physiology). In order to avoid repetition of already discussed aspects of dive-related activities and the physiological response of the human body, the following comments are limited to management and 1st aid advice. 1st aid in Near Drowning: if still underwater, ascend quickly, once on the surface start EAR immediately. The pulse of a cold, unconscious diver is difficult to detect. Once out of the water start CPR if necessary. As 2ndary drowning can even occur hours after the incident, monitor victim closely. Administer O2 while doing EAR (using pocket mask) and ask for professional medical assistance. 1st aid in Arterial Gas Embolism (AGE/CAGE): administer 100% O2 and organize trip to the hyperbaric chamber immediately, otherwise call for professional help. Give EAR if required. 1st aid with DCI/DCS: with individuals suspected to suffer from PFO administer pure O2 (shifts pN2 away from tissues to the bloodstream and ultimately to the lungs, where it is degassed quickly). Place person horizontally (reducing blood pressure gradients) and give plenty to drink (increases solubility of N2 - except if DCI victim suffers from urinary blockage). Seek urgent hyperbaric treatment. 1st aid in Diving Emphysema: administer 100% O2 and organize trip to the hyperbaric chamber immediately. Give EAR or CPR if necessary. 1st aid in Pneumothorax: administer 100% O2 and organize trip to the hyperbaric chamber immediately. 1st aid in Middle and Inner Ear Barotrauma: if rupture occurs hold on to a stationary object, until dizziness passes and abort dive. Apply a light bandage onto the affected ear and lay victim with the injured ear down (side-wards). Seek medical attention. 1st aid in Sinus Barotrauma: stop diving and get medical attention; sometimes it helps to inhale warm and steamy air to unblock the sinus; likewise do spicy foods and hot sauces. 1st aid in Gastro-Intestinal Barotrauma: stop ascent, descent to vent gas and relieve discomfort, then slowly re-ascend. Various over-the-counter medication can relief flatulence. Usually leg movement while ascending eases the pressure a bit. 1st aid in Dental Barotrauma: visit dentist as soon as possible, don not attempt to seal off the affected tooth by gluing the pieces together.

Cramps A cramp represents a circulatory stress symptom as a tightly contracted and shortened muscle inhibits proper control of the affected extremities; to reverse the cramp, lengthen the muscle by stretching (fig. 10.16). Carotid sinus reflex It is a circulatory malaise and occurs when excess pressure is applied to the main arteries of the neck. Stop pressure by loosening whatever presses against the neck arteries and stop exertion. Bend over or lie down so that gravity can bring blood back to the head. Signal buddy to start your way up while monitoring the affected diver.

Fig. 10.16: Reliving a cramp by stretching a muscle

Seasickness Often encountered by person susceptible to motion sickness. Medication should be taken well in advance of a boat trip (with somewhat lowered efficiency, but can be taken also on the spot). A diver’s physical position on the vessel can help as well. The person should stay (lay down and close eyes) on deck at fresh air. If in standing position, if helps to focus at the moving water, thereby allowing the eyes and inner ears to sense the same movement, and resolve the supposed sensory conflict. Don’t read, and stay away from diesel exhaust fumes, avoid watching or smelling others who are sick, but provide affected person with moral support (fig. 10.17).

Fig. 10.17: Rough weather can leave the crew

unfit for diving


Disorientation and Vertigo The former usually precedes the latter. When affected by disorientation (due to blue orb syndrome, etc.) stop and grasp stationary object for reference, watch the buddy’s bubbles, check the depth gauges to see which way you’re heading. If affected by vertigo, stop and grasp stationary objects for reference (fig. 10.18).

Fig. 10.18: To fight vertigo, focus on your stream of

bubbles or let little water in your mask and focus on the water line.

If vertigo occurs in mid-water with no references available, hug yourself (the value of a nearby buddy in such a situation is apparent). If symptoms continue, abort the dive. Dehydration Commonly the result of heavy activity, lots of sweating and diving for extended times with no substitution of the lost body fluids. Stop, rest, remove diver from direct sunlight, and give her/him water to drink (no tea, coffee or alcoholics, as these tend to act as diuretics. Drinking seawater does have an even worse effect as it drains more liquid from the body than originally taken up (fig. 10.19; see also Chapter 6, Diving Physiology – Effects of immersion on Circulation).

Fig. 10.19: Dehydration despite excess fluid intake

Poisoning Poisoning is a rather uncommon observation, it may occur before, during, or after dive related activities. The 4 modes of poisoning are ingestion, injection, inhalation, or absorption. The indications of poisoning should include the history, alerted conscious state, altered respiratory rate, altered heart rate, change to the size to the victim’s pupils. The steps in the general 1st aid management of poisoning start with a primary survey and to act accordingly; arrange medical assistance; comfort and reassure victim; monitor victim; try to identify the type and quantity of the poison taken, and when it was taken; contact poison information centre if unsure if victim require medical attention. Vomiting should not be induced after ingestion of a corrosive substance because the corrosive substance may harm again the oesophagus and/or airways on the way up. Instead, it is better to dilute the ingested poison by drinking water or milk. Carbon monoxide (CO) toxicity: CO is toxic as it inhibits O2 take-up by competing with and occupying the binding sites of haemoglobin forming carboxy-hemoglobin. Being a colourless and odourless gas, it can lead to fatal incidents. CO has a 200x higher affinity to haemoglobin than oxygen (fig. 10.20). pCO increases with depth, providing more molecules of CO with each breath from a contaminated air source. Since the number of red blood cells is limited, the effect of CO increases with depth as more and more binding sites are occupied with that gas. At sea-level halftime is about 5½ hours. By breathing pure O2, halftime can be reduced to 1½ hours. CO poisoning usually occurs when breathing contaminated air from a faulty or poorly maintained compressor. Causes for CO inhalation are usually found at the filling station. If not carefully separated, air intake of the compressor can be mixed with exhaust fumes and filled into the compressed air mixture that will end up in the SCUBA tank. Although a taste- and odourless gas, it can be recognized as intoxication drastically reduces state of alertness. In any case immediately end the dive, administer pure O2 and organize trip to the hyperbaric pressure chamber. Inhalation of pressurized O2 helps to reduce lipid per-oxidation in cells.

Fig. 10.20: Treating CO toxicity with O2 improves fast

recovery 0-5% -- normal value 15-20--Headache, Confusion 20-40-- Disorientation, fatigue, nausea, visual changes 40-60 -- Hallucinat., combativeness, coma, shock state 60 or > -- Mortality 50% and over


Carbon Dioxide (CO2) toxicity is not observed in properly designed and maintained diving gear. Some divers don’t ventilate enough (hypoventilation), while others try to save air by “skip-breathing” methods. Under such conditions, CO2 may not be removed efficiently and CO2-levels increase causing hypercapnia. In severe cases this can lead to unconsciousness with no warning as the brain shuts down unnecessary O2 consumers to maintain vital body functions (see also shallow water blackouts). It can also become a problem when scrubbers in rebreathers are not well maintained. As the rate of CO2 production in the body does not increase, depth alone does not increase pCO2 in the alveoli. If an increased level of pCO2 of 10.5kPa (0.1bar) is sensed, the breathing rate is automatically increased to 8-11fold to vent it off.

Fig. 10.21: CO2 dissociation curve

If pCO2 is exceeding that level, the respiratory centre begins to be depressed due to the negative metabolic effects of CO2 (fig. 10.21). Besides a failing respiration, the diver suffers from acidosis, varying degrees of lethargy, narcosis, and finally anaesthesia. Nitrogen Narcosis: about 4/5th of air is N2. At sea level pN2 has no known effect on bodily functions, but at higher partial pressures it can cause varying effects. Mild effects (joviality, loosing cares) can be observed when a diver remains 36m beneath the surface for an hour breathing compressed air. Drowsiness sets on at depths of 45 and 60m (compare with fig. 10.22). At 60 to 75m, strength wanes considerably and the diver becomes clumsy, even useless when remaining at these depths for too long. N2 narcosis has characteristics similar to those of alcohol intoxication, thus earning the nickname “raptures of the depth”. The mechanism of narcotic effects is connected to the behaviour of gases in liquids when under pressure. N2 dissolves in the membranes of the neurons and, because of its physical effect on altering ionic conductance through the membranes, reduces neuronal excitability. The resulting anaesthetizing effect may result in limited visual perception, claustrophobic sensations, reduction of motoric capabilities, and general lack of common sense safety aspects. Narcosis impairs judgement and orientation, making it difficult to monitor depth, diving time, air reserves, and ignoring the presence of the buddy. Ascending to shallower depths helps to redeem the effects of silly behaviour underwater. Highly compressed N2 is so dense that airway resistance can become extreme, sometimes rendering the work of breathing beyond endurance. When experiencing N2-narcosis it manifests itself by a lack of rational behaviour and incapacity to solve rather simple tasks (e.g. performing a simple mathematical calculation like 100-7-7-7, etc.). Immediately ascent to shallower depths, to reverses this effect.

Depth [m]

abs. p [atm]

rel. pO2 [atm]

O2 Air [%]

rel. pN2 [atm]

Nitrox [%]

0 1 0.21 21 0.8 40 10 2 0.42 42 1.6 80 20 3 0.63 63 2.4 120 30 4 0.84 84 3.2 160 40 5 1.05 105 4.0 200 50 6 1.26 125 4.8 240 60 7 1.45 145 5.6 280

Fig. 10.22: Comparison of partial pressures of major gases with depth


Oxygen (O2) toxicity: when the pO2 in the blood rises far above 13.16kPa (0.13bar), the amount of O2 dissolved in the plasma increases markedly. The figure on the right, depicting the O2-hemoglobin dissociation curve, shows that increased pressure causes a large portion of the total O2 to be dissolved in the plasma, rather than bound with haemoglobin. Diving at about 30m (4bar) resulting in a total O2 content of about 29%vol per each 100mL blood (point A of fig. 10.23); 20% of that is bound to haemoglobin and 9% dissolved in the plasma. Target tissues use their normal amount of O2, about 5mL from each 100mL blood. The O2 content on leaving the tissue capillaries is still 24% (point B of fig. 10.23). at this point the pO2 is still about 157.9kPa (1.6bar), which means that O2 is delivered to tissues at this extremely high pressure (instead of the normal 5.26kPa = 0.05bar). Thus, once the alveolar pO2 rises above this critical level, the haemoglobin-O2 buffer mechanism is no longer capable of keeping tissue pO2 within the safe range of 2.63kPa to 7.89kPa; (see Chapter 6, Diving Physiology – Respiration).

Fig. 10.23: Quantity of O2 dissolved in the plasma and

combination with haemoglobin at very high pO2

Molecular O2 has little capability of oxidizing other chemical compounds. It must be first converted into an “activated” form; e.g. oxygen radicals (O⋅), superoxide (O2-⋅), peroxide (HO⋅). Even though small amounts are always present, bodily antioxidants (e.g. enzymes like peroxidase, catalase, dismutase) rapidly neutralize these free radicals. Thus, so long the hemoglobin-O2 buffer functions properly (pO2 =5.26kPa), the oxidating free radicals are rapidly removed. Above a critical pO2 level of 202kPa (2 bar) this buffering mechanism fails allowing the free radicals to literally swamp the enzyme system resulting in serious destructive or even lethal effects (brain dysfunction). Even though the body responds by blood vessel constriction to counteract that oversupply, tissue oxidation occurs. Especially sensitive is nervous tissue with its high lipid contents, as it causes the oxidation of poly-unsaturated fatty acids of cell membranes and cellular enzymes. Acute O2-poisoning is detrimental to many bodily tissues, especially to the brain. For most people, exposure to 4 bar (190msw) will cause seizures followed by coma. Exercise greatly increases a diver’s susceptibility to O2 toxicity, causing symptoms to appear much earlier than in a resting person. In fact one does not have to go to these depths; intoxication can be already achieved when using a different breathing gas mixture with elevated pO2, or CCR rebreathers using pure O2. With standard OCR gear, though these effects are only observable when diving at 66m for 140min (pO2 >33% or 1.6atm). Pulmonary O2-toxicity can occur even after a person is exposed to a pO2 of only 101kPa (1bar). Even though it does not show the acute effects, 12h after exposure, the lining of the trachea, bronchi, and alveoli become damaged (lung passageways congestion, oedema, and atelectasis). This can be also observed after 18-48 hours of exposure to pO2 of only 50kPa (0.5atm). Symptoms include chest pain, coughing and blackouting. CNS O2 toxicity occurs much more quickly at pO2 levels above a range of about 1.4 to 2atm’s, or seven to ten times the normal concentration at sea level. Symptoms include nausea, abnormal vision or hearing, breathing difficulty, anxiety, confusion, fatigue, disorientation, irritability, twitching of face, lips, or hands, dizziness, and convulsion. When experiencing O2-poisoning end dive immediately; symptoms reverse when pO2 levels drop upon ascent. Administer pure O2 and organize professional medical help, as drowning or air embolisms are likely possibilities if the convulsing diver loses the regulator mouthpiece.


Hypothermia The body of a hypothermic person reacts with constrictions of blood vessels in the skin and then deeper within limps to prevent heat loss. The signs and symptoms of mild hypothermia range from numbness of extremities; to pallor or blueness of extremities, and shivering (to generate body heat – fig. 10.24). Signs and symptoms of moderate to severe hypothermia range from uncontrollable shivering, incoordination, no-shivering in spite of cold, muscle rigidity, apathy, altered conscious state, to slow respiration and pulse, as well as heart irregularities. According to the severity of the chilling, several steps should be taken. For mild chilling, get the diver out of the water, administer warmed fluids (water), bundle person in up in dry clothes to prevent further heat loss and allow the body to rewarm itself gradually. Handle victim gently and lay them flat, conduct primary survey, insolate from environment with blankets or clothing, cover with plastic sheets to prevent any further heat losses caused by wind, provide warm drinks if victim is conscious, stable and can swallow; seek medical assistance. Refrain from administering alcohol as it dilates peripheral blood vessels and promotes further cooling. Chilling that goes further is a medical emergency, as the diver’s heart beat suffers from arrhythmias or can cease beating altogether if handled roughly. Immediately protect diver against further heat loss with warm layers over the diver and between the ground-layer and the diver. In severe hypothermic cases, the diver will be unconscious or appear even dead. Continuously check for breathing and pulse to provide CPR should it become necessary. Hyperthermia Hyperthermia can occur when remaining out of the water without removing the wetsuit. Some indications of heat exhaustion include profuse sweating; rapid, weak pulse; pale or flushed skin; headaches; nausea or vomiting; thirst! If not treated adequately, a heat stroke may be the next step and is indicated by absence of sweat, dry, red and hot skin; Her/his conscious state deteriorates; pulse becomes rapid and strong; convulsions may occur.

Fig. 10.24: Body core temperatures: body temperature normally varies within a healthy range; outside of that

range problems start to occur

For mild overheating, place diver under shade, lie down, remove wetsuit, replace water loss and reduce body temperature by administering cool water. Heat stroke represents a medical emergency, but sips of cool fluids (presumed victim is still conscious) on the way to emergency facilities can be administered, keep diver reclined or laid down to reduce for shock, fan vigorously (don’t cool victim to the point of chilling). Venomous Bites and Stings Many marine organisms can result in painful (some even lethal) injuries. Venoms that are injected into the diver are usually transported by the lymphatic system. Muscular movement drives the flow of venoms through the body. Pressure-immobilization technique is the only direct response to injected venoms; it involves applying pressure to the envenomated site by promptly placing a firm bandage around the site and bandaging as much as possible the affected limb. The limb is then immobilized to restrict muscular movement. Other types of envenomation that also require pressure-immobilization include bites from snakes, funnel-web spider, cone, bee-, or wasp-stings, bites of ants in allergic persons, as well as severe tick reaction. The 1st aid management for a redback (Latrodectus hasselti) spider bite: reassure victim, apply an ice pack for pain relief, and arrange for transport to a medical facility. Pressure-immobilization is not recommended with stonefish and other venomous fish spine-injuries as this increases pain and local tissue damage; instead hot water immersion is used in the management of fish spine injuries. Heat helps to break down these types of toxin and the hot water provides pain relief. 45-50°C; i.e. as hot as can be tolerated without scalding. Anaphylactic shock: A person stung by an insect who is looking flushed and is beginning to have difficulty breathing starts to have severe allergic reaction (anaphylaxis). Arrange urgent medical aid, remove the barb if possible, apply pressure-immobilization and be prepared to resuscitate if necessary. The more series consequences are observable when venomenation occurs in aquatic habitats. Fig. 10.25 lists some of the most common marine stings and injuries associated with reef animals.


Box jellyfish (Chironex fleckeri): never use methylated spirit or alcohol. Domestic vinegars should be poured liberally over the tentacles to inactivate stinging cells as soon as possible. The tentacles may then be removed. Artificial respiration and cardiac massage may be required. Where antivenin is unavailable, pressure-immobilisation may be used on limbs after inactivation of stinging cells, while the patient is being transported to the nearest medical centre.

Cone shells (Conus geographus) Pressure immobilisation in 1st aid should be applied and left in place until resuscitation facilities are available. This is a medical emergency. Assisted ventilation may be needed. Tetanus prophylaxis should be updated if required. There is at present no antivenin for cone shell stings.

Octopus (Hapalochlaena lunulat, H. maculosa): Pressure-immobilization is a recommended 1st aid. Prolonged artificial respiration may also be required.

Fig. 10.25: Selected dangerous marine species;

clockwise: Box-Jelly, Blue-ringed Octopus, Stonefish, Cone shell

May require supportive treatment including mechanical ventilation until the effects of the toxin disappear. Mouth to mouth resuscitation can keep the victim alive and the poison gradually wears off after 24 hrs, apparently leaving no side effects. There is at present no antivenin for cone shell stings.

Stonefish stings (Synanceja trachynis, S. verrucosus): Do not attempt to restrict the movement of the injected toxin. Bathing or immersing the stung area in hot water may be effective in reducing the pain. Transport the patient to the nearest medical centre. Hospitalisation for intravenous narcotic analgesia, local anaesthetic infiltration or regional block may be required. Definitive management consists of administration of stonefish antivenin. Indications for antivenin include severe pain, systemic symptoms or signs of (weakness, paralysis) and injection of a large amount of venom. Do not apply pressure immobilization.

Burns Even though divers are less exposed to burns (flame, hot objects, hot air, hot water, and steam, chemical, electrical and cold) some are of significance; i.e. radiation burns caused by the sun. The three major classifications of burns discriminate between superficial-involves the top layers of the epidermis (fig. 10.26); partial thickness-involves the epidermis and parts of the dermal layers; and full thickness-involves burning to both epidermis and dermal layers. In addition, subcutaneous tissues including nerves are being damaged. Indications of full thickness burn are painless itself but may be pain associated with partial thickness around the site, crack and dry appearance, white or charred in colour. Immediate attention for burns is required when a flame or scald burn the size of the victim’s palm; any flame or scald burn involving the hands, face, perineum or genitals; any chemical burns; electrical burns; burns with suspected with respiratory track involvement. The general steps in 1st aid management of burns is to avoid danger, relocate the victim to a safe environment when it is safe to do so, conduct primary survey, arrange medical aid if required, immediately cool the affected area with water for up to 20 minutes, remove all jewellery from affected area, elevate burned limps and cover area with a clean, sterile lint-free dressing provide oxygen if available to any victim with a significant burn injury.

Fig. 10.26: The 3 categories classifying burns


11. Oxygen Provider Why O2 O2, of course, is part of the air we breathe. It is a colorless, odorless and tasteless gas that constitutes about 21% of the air. For most organisms, it is an essential chemical to maintain metabolic processes. The amount of O2 delivered to a tissue depends on the pO2concentration in the blood and the rate of blood flowing through the tissues (perfusion). Since the haemoglobin is normally almost fully saturated, the blood usually cannot carry more than maximal carrying capacity determined by the bonding sites of the red blood cells. And still, if the inhaled gas is made up of pure O2, more of that gas can be taken up as it becomes dissolved into the plasma (compare O2-toxicity of previous chapter). Since air already contains 21% O2, what is used here is more accurately known as supplemental O2, i.e., an inhaled O2concentration greater than the 21%. The administration of 100% O2 in DCI victims may prevent existing bubbles from expanding, or even make them shrink enough to provide symptomatic relief. Another reason to have supplemental O2 available is to treat hypoxia, found in victims of near-drowning accidents (fig. 11.1). Oxygen can be very helpful for any hypoxic condition but primarily as treatment for DCS/AGE. Therefore, when circulation is impaired or blood O2 content is lowered, prompt provision of extra O2 may be very valuable; e.g. asthma, blood loss, envenomation, fractures, head injury, heart attack, stroke, shock, all forms of resuscitation, near drowning, inhalation of toxic gases (smoke or fumes), DCI, pulmonary barotrauma, Handling O2 As 100% oxygen is a combustion booster, there are As 100% oxygen is a combustion booster, there are serious risks when handling an O2 emergency kit; these include fire hazard (spontaneous ignition), potential explosion of cylinder, endangering casualty by improper use of certain positive pressure equipment. Therefore, it is essential to wipe off any grease (make-up, sun-taint lotion, etc.) from the face of the victim as adiabatic changes may cause ignition utilizing grease of any source as potential fuel which would result in severe internal burns to a potential victim!

Fig. 11.1: Administering O2 to a diver in need

Administering O2 Administering O2 to a non-breathing victim requires that s/he lies down horizontally, without elevating the legs. As indicated in the flowchart on the right, such a victim is best served with a pocket mask. An unconscious but breathing victim is either served with a demand valve and mask or with a non-rebreather mask (depending on the tolerability of the person) and under continuos surveillance should be kept in a stable lateral position. When assessing the effectiveness of an O2 delivery system, some factors should be considered like O2-concentration achievable, the time it takes to reach maximal O2-concentration, the flow rates necessary to achieve the desired concentration and the breathing resistance of the system (fig. 11.2).

Fig. 11.2: The appropriate choice in O2-treatment

Usually when one diver requires O2-treatment, the buddy may likewise require treatment. Thus, oxygen providers should plan to have an adequate O2 supply to allow casualties to breath high concentrations of O2 for the period it probably takes for the emergency crew to arrive at the site, or for the casualties to be delivered to an appropriate medical facility. N.B.: perform the head-tilt to the victim to enable easy ventilation! In such a case this time available till arrival of professional help must be taken in consideration as the O2 tank capacity is limited and more rapidly used up with two consumers than with one only. The end of this chapter states a simple example of how to calculate the O2 demand when using a particular mask.


Practical Aspects It is not desirable to deplete an O2 cylinder as moisture and other contaminants may deteriorate the interior. An O2 system must be charged after use or maintained at least once a year. Disposable parts are discarded after use, non-disposable parts are rinsed with cold water, washed with detergent, rinsed again, dried, and mounted together for testing. The system must be turned of after testing to relieve pressure on valves and other parts. Disassembled properly and placed into the proper storage compartment for rapid assemblage in an emergency (fig. 11.3). Storage should be away from heat in a well-ventilated area as leaking O2 in an enclosed compartment can explode suddenly when ignited.

Fig. 11.3: The entire O2 provider kit

Putting the System together The system must be assembled and ready to use prior to any dive (unpressurized with main valve closed) and stored in a clean, rapidly accessible site. This enables quick access should an emergency require O2 treatment. The core element of the system is the C-size cylinder at a working pressure of 16.3Mpa (holding a total volume of 490L pure O2). When putting the system together, the hands should be free of any grease, oil and clean, the area well ventilated with no open flames around. While the O2-outlet is facing away from the operator, attach the valve wrench and gradually open the valve slightly to remove any debris trapped in the bullnose adapter (mounted on the cylinder). After closing it again check that the Bodok seal (graphite impregnated neoprene washer) is properly placed in the regulator’s internal socket (in case of damaged or lost seal it is essential to have always some spare seals stored in the O2-kit to maintain a working system). The regulator is required to reduce the cylinder pressure to an outlet pressure compatible with the delivery equipment (fig. 11.5). Remove the wrench of the cylinder valve and place the regulator with the pin-index over the bullnose adapter in such a way that the locating pins on the reg are lined up with the matching holes on the cylinder valve pillar (fig. 11.4). The yoke screw is then tightened firmly enough to hold the regulator in position – the regulator will be further secured by the O2-pressure once the valve is opened. All the flow valves should be closed so that leaks can be detected when the valve is opened. Placing the wrench back and opening the valve, to pressurize the regulator slowly, gives the first reading on the pressure gauge. Closing the valve again should still give a stable reading; the slightest drop indicates a leakage in the system.

Fig. 11.4: Docking the reg onto the Bullnose adapter

Fig. 11.5: LSP regulator

When using the system it is recommended that the cylinder valve is fully opened and turned back ½ to ¼ of a turn. Having set up the main system, the delivery devices should be testes to ensure they are working adequately. There are several delivery outlets attached to the reg. Two high-flow outlets used for the demand valve, and one variable-flow outlet for the constant flow devices (simple face mask, non-rebreather mask, pocket mask or nasal cannula). The variable flow can be set to varying flow-rates.


Demand Valve A very simple and effective way to deliver near 100% O2 to a breathing victim (fig. 11.6). It is attached to a pressure converter (mounted onto the O2-tank, with integrated 1st and 2nd stage) allowing breathing like from a SCUBA tank. The benefits with using a demand valve are based on the ease of use and the high O2 concentration achievable. It is not used if breathing is weak as there may be insufficient suction to open the valve. Due to the breathing resistance of a demand system, a rapidly breathing hyperventilating victim may have difficulties breathing from it. Furthermore, a poor seal of the mask may not open the valve effectively and air will be entrained and dilute the O2-concentration. Should EAR be necessary, the rescuer can use the demand valve by breathing pure O2 and delivering the exhaled breath to the victim.

Fig. 11.6: Demand valve and mask

When placing a manually triggered O2 devices onto the face of the victim and pressing the purge button, the rescuer risks to inflate the victim’s stomach (resulting in regurgitation) or even a lung-barotrauma. Constant flow system The pressure converter can also be operated in a constant flow mode (fig. 11.7). Restrictors (switchable orifice with indicator at the lateral end of the regulator) provide flow rates from 3, 5, 8, 15, 20, or 25L/min. The most suitable flow-rate is based on the desired O2-concentration, amount of O2 available, the flow-rates available, and the likely response time of the ambulance. When using the constant flow system, the O2-concentration depends on the seal on the face, minute breathing volume of the victim, and the O2 flow-rate. The following delivery devices can be attached when using a constant flow system: i) nasal cannula: for a conscious victim that is able to

talk, drink and cough; O2 concentrations range from 24-60% at 6-15L/min.

i) simple face mask: suitable for a spontaneously breathing victim; it is capable of delivering 35-60% O2 at flow rates of 6-15L/min (55% at 8L/min).

i) non-rebreather: it is used when the victim has difficulties with the demand system, or is breathing too fast; it delivers up to 95% O2 when using a flow rate of 10-15L/min. If using this mask (fig. 11.8), it is important to ensure the reservoir is distended with O2 and the flow-rate set to 15L/min before the mask is fitted, and when fitted to the victim that the flow rate adjusted so the reservoir is not deflated completely (place thumb over the reservoir valve to fill it), not doing so, may render breathing for the victim difficult (with flow-rates to low), or even impossible. Once fitted, an adequate flow-rate must be chosen (safes O2) and is reached when the bag de- and inflates according to the victim’s breathing rate.

Fig. 11.7: Simple face mask

Fig. 11.8: Non-rebreather mask


i) pocket mask: it is designed for use with EAR in situations when mouth-to-mouth or mouth-to-nose contact may not be acceptable (fig. 11.9). A 1-way valve can be attached to redirect the exhaled air of the victim. Attaching the hose connector to the constant flow system enables EAR administering enriched O2 to the victim.

Practical Application: Example1: a conscious and breathing victim, suspected of having DDC, is administered with O2 using a 3L O2-tank (16.3MPa), how long can a breathing victim use it (at 15 breaths/min with a tidal volume of app.0.5L) when fitted with a demand valve?

Fig. 11.9: Pocket mask

16.3MPa ⋅ 3L 1 ⋅ ____1____

101.3kPa ⋅ 3 ⋅ __1 min__ 15 breaths

= 32min*

(*) as each breath is split into an inhalation and exhalation cycle, the total time available doubles to 64mins Example2: a conscious but hyperventilating victim that ran out of air performed a rapid emergency ascent from a 13m deep dive. The dive leader immediately administers O2 using a standard C-size cylinder (160bar) and the non-rebreather mask. The emergency services have been alerted. How long can the victim be supplied with O2 when a flow-rate of 20L/min is used?

160bar ⋅ 3L 1 ⋅ __1 min__

20L = 24 min

Recompression Therapy – The necessary 2nd Step O2 is merely the beginning 1st step. A “typical” multi-lock, multi-place recompression chamber session has to follow each dive accident in which DCI or DCS is suspected. Hyperbaric Chambers If a diver is brought to the surface slowly, the dissolved N2 is eliminated through the lungs rapidly enough to prevent DCS. About 2/3rd is vented off within the 1st hour, and about 90% within the following 6h. The recommended treatment of DCI / DCS is recompression (in part with pure O2) in a hyperbaric chamber. The hyperbaric chamber to experience on this course is the one stationed at Wesely Hospital (Brisbane). Even though a group of divers do everything “by the book” to prevent a trip into the chamber, there are always some individuals that still suffer from DCI. This is the small unpredictable but significant group of divers that account for DCI accidents (some 3.4 in every 10⋅E3 dives in the recreational diving industry). On the other hand, there are divers that intentionally (or not knowingly because not properly trained) dive beyond the limits of the tables or even the dive computer. Hyperbaric chambers and the scientific diver General characteristics: the 137cm diameter chamber is the most commonly found in the diving community. It is relatively small, economical and capable of treating persons with an inside tender, and rotating staff during treatment. Most chambers are rated to 6atm’s absolute pressure (50msw), even though most DCI treatment is conducted at 18msw. Compressors and gas sources: to pressurize a chamber, compressors or sources of already compressed gases are required. Backups systems take over in case the primary system fails and should be able to fill a chamber at least to the working pressure for the total volume and duration of the chamber; i.e. 1.5⋅1.5⋅2m (=4500L) with a working pressure of 50bars requires a total gas volume of 225⋅E3L + 5% extra to account for CO2 build-up.

Fig. 11.10: Double-lock Hyperbaric chamber


Chamber Types and their uses: a cost-effective treatment that is rapidly achieved can wreak havoc with routine therapeutical use of the chamber. Monoplace single lock chambers are designed for hyperbaric medical therapy such as gas gangrene can operate with working pressures of up to 3 atms absolute (20msw). Whereas, multiplace double lock chambers are the more suitable type of chambers for the treatment of DCI (fig. 11.10). Chamber Operation: a number of extra operational personnel is required to guarantee a safe operation of the chamber. A supervisor usually controls the entire chamber operation and must be able to immediately intervene should it be required. The outside operator is the person monitoring and controlling the chamber pressure cycle at the control desk. The tender is a person taking care of the DCI victim observing all vital functions while in the chamber. This person is also the interfering person should the victim suffer from O2 seizures. In some occasions when the standard protocols fail to yield good results, diving medical officers are consulted to direct modifications of the treatment. Operational procedures: a non-life threatening recompression treatment schedule will usually be run at 18msw pressure utilizing alternative breathing gas (O2 and compressed air alternatively) and lasts from about 5 to 24 hours. Regular ventilation with fresh gas is required to substitute the CO2-enriched air. Specific safety concerns: when dealing with pure O2, fire is a potential hazard. To reduce chamber fire risk, fire suppression systems must be available. These risk include the presence of burnable material, a combustion-supporting agent (O2), and an ignition source. Therefore, anything entering the chamber is kept “oxygen clean”, that is all greases and oils are eliminated, and that includes make-up and applied lipstick. A chamber experience: doing a chamber ride is unique experience to feel physics in action. Chambers are noisy places; gases hiss in and out through small orifices during pressurization and venting and can be too loud to talk over. As gas density increases with pressure, voices become altered and sometimes hard to understand. The rapid increase in temperature and humidity renders the atmosphere inside hot and stuffy. During ascent on the other hand, the chamber cools down and clouds of humidity will form. Example of Recompression according to US-Navy: A diver who has been breathing compressed air at 60m with a total bottom time of 60min, is decompressed according to the schedule shown on the right. Thus, for a work period on the bottom of only 1h, the total decompression time is about 180mins or 3h.

10mins at 15m 17mins at 12m 19mins at 10m 50mins at 6m 84mins at 3m

Example of Recompression Therapy: Modified USN table 6 (fig. 11.11)

Depth 18msw Atmosphere: air mix Use: treatment of DCI Comment: can be extended if required or changed to saturation dive

The green areas on the graph represent the time spent by the patient breathing pure O2 using a hood and neck seal. To further reduce the potential for O2 toxicity, regular breaks in O2-therapy are scheduled – shown as the blank areas on the tables.

Fig. 11.11: USN Recompression

Example of Recompression Therapy: Modified Comex 30 TT30 (fig. 11.12)

Depth: 30msw Atmosphere: Heliox Use: treatment of DCS Comment: can be extended to several days

The red areas on the Comex 30 graph represent the time spent by the patient breathing a 50/50 mix of O2 and He – the patient cannot breath 100% O2 at depths greater than 18msw due to the increased risk of O2 toxicity.

Fig. 11.12: Comex Recompression


12. Diving Environment Physical Aspects of water movement The most common force creating water waves is the wind. As the wind blows across a smooth water surface, the friction between the air and the water stretches the surface, resulting in small wrinkles or ripples. As the waves become larger, the force returning the water to its level state changes from surface tension to gravity. From Fetch to Waves A few definitions - waves are measured in terms of their height, length and period (fig. 12.1). The height of a wave it the vertical distance from its crest (lowest point) to its trough (highest point) in meter. The wavelength is the horizontal distance between successive crests (or troughs), while the period is the time required for two successive crests (troughs) to pass a given point. Fetch is the contact zone of the wind and water. A swell is a wave that is fairly regular in height, period, and direction. Water waves develop under the influence of newly formed wind as air pressure changes on the surface of the water whereas frictional drag of the air develops ripples on the surface. The stronger the wind, the more likely the ripples evolve into waves.

Fig. 12.1: Wave terminology

Waves in shallow water: as a train of waves move into shallower water, the hard substrate of the coastal bottom increases to interfere with the orbital motion of the water column within the wave. The orbits flatten into ellipses, and the net movement of the water body turns into a back-and-forth surge motion (fig. 12.2). Diving in surge will sweep the diver back and forth. Therefore, diving in stronger surges should be avoided. As the lower portion of a wave is slowed in shallow water, the top portion moves faster. When the depth to the bottom is about twice the height of the wave, the crest starts to heighten even further, resulting on decreased wavelength and velocity. Eventually, at a depth of 1.3 the wave height, when the steeper side of the crest inclines forward >60°, the wave becomes unstable and breaks. It breaks if the ratio C/D becomes <3/4:

Fig. 12.2: Surfzone;

A, wavelength of the pelagial

B, wavelength in shallow-w.

C, piling wave D, wave depth Surf The broken wave, known as surf, forms white water areas in which the waves give up their energy and where turbulent water motion replaces systematic wave action. The remaining momentum carries the broken wave landward into the swash zone of the beach. On a shallow sloping beach, a moderate swell will result in spilling breakers (fig. 12.3). Whereas on a moderately sloping area, the same swell will result in plunging breakers. Therefore, shore entries under such conditions should be done only once completely geared up (incl. fins, shuffling backwards while keeping an eye on incoming waves).

Fig. 12.3: Spilling breaker: on a gradually sloping beach, a moderately large swell will form a spilling

breaker; Plunging breakers release their energy quickly with tremendous force; this type of surf forms from

large swells over a moderately steep bottom.


Tides They are the periodic rising and falling of water levels primarily due to the gravitational attraction of the moon and secondarily of the sun upon the earth (fig. 12.4). Spring tides form when the moon and the sun line up to “pull” in the same direction, whereas a neap tide results when the sun “opposes” the gravitational attraction of the moon. Diurnal tides are those that generate a low and a high within a 24h period. Semi-diurnal tides result in 2 high and 2 low tide cycles within the same period of time. Mixed tides represent a combination of diurnal- and semi-diurnal cycles. In any case, tides generate horizontal water movement in and out over the duration of the tidal period; this is known as the tidal current). Seiches: when the surface of a large, partly enclosed body of water, a fresh-water lake, a bay, or a harbor, is disturbed, long waves may be established which rhythmically oscillate as they reflect from opposite ends of the basin (fig. 12.5).

Fig. 12.5: Mono-nodal and bimodal seiches

Fig. 12.4a & b: Tides; causes and effects

MHWS: Mean High Water Springs MHW: Mean High Water. MLW: Mean Low Water. MWLS: Mean Low Water Springs

Currents and how to deal with them Longshore current: waves approaching the shore at an angle driven by winds running along the coast, result in a current that is parallel to the shoreline. Rip current: water masses washed onto the coast find their way back to the sea by making its way through zones of least resistance. Rip currents can be permanent (due to rocky substrate), fixed (hole or gully in the sediment), flash (a unique rip current caused by a large surf build-up), or travelling (propelled along the shoreline – fig. 12.6). Wind current: is an offshore current in large bodies of water driven by the wind under the influence of the Coriolis force (deflection is clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere).

Fig. 12.6: Rip current

Dealing with currents along the shore: when unexpectedly caught in a current, return upstream on the bottom, swim perpendicular to get clear of it, exit at a pre-planned alternative site, or obtain positive buoyancy and signal for assistance. Dealing with open water currents (boat): always begin dive against the current - unless making a drift dive. Descend down the anchor or weighted line. Have 30m long trail line ready in case a diver gets drifted off. Leave a lookout on the boat (dive supervisor). Upwelling can affect a dive, when disembarking from a vessel or boat (fig. 12.7). Under such conditions the vertical flow of cooler water from the depth to the surface pushes the diver towards the surface, requiring extra negative buoyancy. Downwelling, is less frequently observed as it is a phenomenon limited to the open ocean (fig. 12.7).

Fig. 12.7: Up- and Downwelling


Thermal and salinity Changes Seawater temperature and salinity not only changes according to the season, but also can be a local phenomenon and affect visibility (fig. 12.8). Thermal stratification (thermocline): surface water (to a certain depth) is warmed up during the summer months, beneath this layer cooler and denser water maintains the original temperature. The demarcation between these to layers forms the thermocline; more predominant in inland waters than in the ocean. In the absence of mixing, a thermocline can be quite stable, and the transition boundary very abrupt (few centimetres). Saline stratification (halocline): is a horizontal boundary layer between waters of differing salinity. Here, lighter fresh water floats on top of denser salt water. When the boundary layer of a halocline is disturbed, as by a diver swimming through the interface, the visual effect is similar to frosted glass.

Fig. 12.8: Thermocline and halocline: temperature and

salinity change with depth in seawater Weather Conditions Being familiar with the weather keeps the risk-potential during a dive acceptably low. Squalls (brief, intense showers) can be accepted, whereas storms are an increased risk factor. When travelling aboard a boat, wind can affect surface conditions along with decreased temperatures, and favouring seasickness. Winds exceeding 10m/s (20knots) are considered the threshold limit for diving. Even though such high-speed conditions are seen as a big no-no for diving exceptions can be made if a protected area provides an acceptable low-risk-dive.

Sea Wind State of surface, sea, wave height

Description F Description v [m/s] knots Smooth 0 Calm 0.0 - 0.2 <1 Mirror like, glassy Rippled 1 Light air 0.3 - 1.5 1 - 3 Small ripples, no foam crests Gentle 2 Light breeze 1.6 - 3.3 4 - 6 Small wavelets, crests glassy (0-0.3m) Gentle 2 Gentle breeze 3.4 - 5.4 7 – 10 Crests break, foam glassy, occasionally

whitecaps (0.3-0.6m) Light 3 Mod. breeze 5.5 - 7.9 11-16 Waves small, becoming longer, whitecaps

frequent Moderate 4 Fresh breeze 8.0 - 10.7 17-21 Moderate waves, whitecaps dominate, some

spray (0.6-1.2m) Heavy 5 Strong breeze 10.8-13.8 22-27 Large waves, crests with white foam, some

spray (1.2m-2.4m) Very heavy 6 Near gale 13.9-17.1 28-33 Sea heaps up, white foam breaking from waves

in streaks (2.4-4m) - - Gale 17.2-20.7 34-40 Moderately high waves, edges of crests break in

spindrift, foam blows in marked streaks (2-4m) High 7 Strong gale 20.8-24.4 41-47 High waves, dense streaks, crests roll, spray

reduces visibility Very high 8 Storm 24.5-28.4 48-55 Very high waves, overhanging crests, foam

renders sea white, tumbling of the sea is shock-like, low visibility (6-9m)

Exceptionally 9 Violent storm 28.5-32.6 56-63 Exceptionally high waves, edges of crests are blown into forth, low visibility (9-14m)

Exceptionally 9 Cyclone 32.7-36.9 >64 Air filled with foam and spray, sea completely white, no visibility (>14m)

Bottom Conditions The type of bottom at the diving area can affect visibility, aquatic life present in the water, challenging navigation skills, interfere with dive planning, and equipment requirements. Generally wear protective clothing on any dive, as cuts and stings (even accidental and minor) can lead to serious fatal infections. Make sure that “dangling” gear does not get trapped or smashed against rocky substrate


Diving Environments (Fresh vs. Saltwater) The ocean environment requires a different planning and preparation than a fresh-water dive. Coral reef-, kelp forest-, estuary-, or polar regions dives - though all marine - have their particularities as well. Likewise, lake-, quarry-, or spring-dives should determine the planing aspect and equipment considerations. All environmental diving activities have something in common; they all require specialized knowledge, equipment, and skills. Man-made structures like jetties, piers, and wharves can pose dangers from waves, currents, poor visibility, sharp objects (oysters), boat traffic, fishing lines (entanglement), lost hooks; entrapment, in some cases even syringes from intravenous drug users and shattered glass from beverages. Therefore, always wear gloves and boots protecting hands and feet; don’t forget to look at the bottom before putting feet or knees down (it could be a stinging ray or a stone-fish!). Diving in the vicinity of active pipelines is discouraged as they may discharge pollutants or if next to an intake suck a diver in if suddenly reactivated after an operational break. Biological Aspects (Aquatic Life) Intertidal life: houses flora and fauna in the region between high and low tides. These are adapted to withstand dehydration, temperature extremes and strong water movement. Planktonic life: passively drifting and floating life forms. Many organisms some time in their lifecycles have planktonic stages. Phytoplankton is composed of autotrophic algae that utilize sunlight and are usually grazed upon. Nektonic life: free-swimming organisms which are able to propel themselves through the water. Many organisms spend part of their life in pelagic waters before returning to a benthic lifestyle and v.v. Benthic lifeforms: bottom-dwelling organisms that are either sedentary or motile. Hazardous marine and freshwater animals: range from cnidarians (hydra, and jellyfish), carnivorous predators (shark, barracuda, etc.), stinging fauna (sponges, jelly fish, bristle worms, cone shell, seastar, urchin, ray, stone-fish, etc), to dangerous reptiles (sea-snake, or saltwater crocodile).

Fig. 12.9: Model of biomass transfer; the amount of

each level is the approximate amount of news biomass that can be produced by eating all the amount shown at

the next lower level.

Poisonous animals: found in creatures whose tissue, either in part or in their entirety are toxic. Marine oral toxins are small molecules that do not decompose under the influence of heat; e.g. paralytic shellfish poisoning (PSP), ciguatera fish poisoning, saurine poisoning, tetradoxin poisoning (TXT), etc. Venomous animals: creatures capable of producing a toxin in specialized glands and delivering tiny doses of it through a sting. Unlike oral toxins, these are macromolecules that are not heat stable or acid-tolerant; e.g. sting of box jellies (Chironex fleckeri), scorpion-fish, stone-fish, etc. (see chapter 10 – First Aid; Venomous Bites) To avoid larger predators do not swim in infested waters, do not spear-fish, do not feed, do not harass, use anti-shark electroshock devices (shark shield24).

24 http://www.aquanaut.com.au/scuba.gen/aquaproduct/1/311


13. Diving Equipment Scuba Systems There are several categories of Self-Contained Underwater Breathing Apparatus (SCUBA). Open-circuit SCUBA is the most commonly used, while the others are gradually becoming widespread. Closed Circuit SCUBA (CCR): This is a rebreathing systems that allows breathing ones own air over and over again and does not need a constant supply of fresh O2 (fig. 13.1). It uses a scrubbing unit that traps exhaled CO2 - this is accomplished through the use of a canister filled with sodium hydroxide (NaOH) and calcium oxide (CaO) reacts with CO2 to form a solid calcium carbonate (CaCO3) precipitate.

CO2 + H2O → H2CO3. 2NaOH + H2CO3 → Na2CO2 + 2H2O Na2CO2 + CaO → CaCO3 + 2NaOH

The consumed O2 is replaced by constant flow from a small tank of pure O2 into the breathing loop. A solid-state O2 sensor monitors the pO2 in the breathing loop and send this information to a microprocessor that controls the O2-delivery system. O2 CCRs, besides being quite expensive, are limited to "no decompression" depths and carry a danger of oxygen toxicity. Semi-closed SCUBA (SCR): these rebreathers use gas mixtures (N2-O2 or He-O2) as its gas supply. Such rebreathers carry both a pure O2- and mixed gas tank. A diver using a semi-closed rebreather can go to greater depths without risking O2 toxicity as they maintain the proper O2 concentration. Part of the exhaled breath is recycled, while allowing some gas to escape into the water. Selective O2-sensors connected to an electronic circuit monitor the partial oxygen pressure (pO2) and add fresh oxygen once the pO2-level falls below a preset value. Unfortunately scrubber efficiency is both temperature and depth dependent. Scrubbing efficiency at 170m is about 20% compared to 90% at about 19m. SCRs are cheaper than CCRs but are problematic when performing heavy work under water (hypoxic response). SCRs are of two main types: those that control O2 input by flow control, such as passing the gas through a calibrated orifice, and those that use a counter-lung to adjust the gas by a mechanical ratchet or bellows arrangement. Ascents with a counter-lung cause release of bubbles (since gas cannot be put back into the high pressure containers) and descents require addition of gas to maintain system volume. As a result, too many depth changes can deplete the gas supply even though the diver does not actually use gas. In order to reduce the chances of shallow-water blackouts, diving with re-breathers requires venting off the system with fresh O2 prior to ascending, to reduce CO2 intoxication. Exhaling through the nose is sufficient to reach this effect.

Fig. 13.1: Rebreather

And still rebreathers have several advantages compared to conventional SCUBA; these include: • better gas efficiency - as conventional SCUBA

does not consume all of the O2, a lot is wasted. CCRs replace only the consumed O2 (fig. 13.2)

• lighter weight - compressed air contains 78% N2 CCR don't carry N2 along with the O2;

• less decompression - because the N2 in the system, which is involved in DCI, is kept to a minimum,

Fig. 13.2: CCR dive time available (at rest) using a 5L

O2 tank filled to 200bar of which 150 are used

decompression is less complicated and divers can stay down longer than with conventional SCUBA; • silence - rebreathers produce few or no bubbles, so they don't disturb marine life or reveal a diver's presence.


Open-Circuit SCUBA (OCR): is the standard equipment of the modern dive industry; it is made up of the SCUBA tank, the 1st stage (intermediate pressure conversion), connecting hoses, and the 2nd stage (regulator). SCUBA Cylinders Cylinder or tanks are nowadays made of steel, aluminium, or carbon-fiber. Every high-pressure cylinder is also fitted with particular markings (fig. 13.3). These stamped codes reveal the cylinder’s material, capacity, service pressure, manufacturer, testing info, etc. Care of SCUBA cylinders: Corrosion in metallic cylinders is of concern. As water vapor can affect the level of corrosion of the tank, compressed air must be free of humidity. Rust (Fe2O3) in steel tanks and Aluminium oxide (Al2O3) can obstruct the regulator or even cause blockage of the 1st stage of the pressure conversion unit of the attached tank manifolds. In addition, over time corrosion in metallic tanks uses up part of the O2. Thus, shifting the partial pressure from the normal relationship to one favoring N2. If whitish mist is detected when opening the valve, sloshing is heard when tilting the tank, or if the air has an “odor” that can’t be linked to the compressor, then immediately send it for inspection. Some basic rules in cylinder care include:

Fig. 13.3: Scuba tank markings: 1 Gas type; 2 owner, 3

scuba equipment, 4 service pressure, 5 EU design permit, 6 country of manufacture, 7, manufacturer, 8

serial number, 9 standard, 10 test pressure, 11 EU trademark, 12 repeat test, 13 empty weight, 14

minimum volume, 15 galvanized

• Always handle pressurized cylinders with care (they may become cruising torpedoes when damaged), protect the valve while transporting them.

• Do fill cylinders slowly (<35bar/min). • Do prevent moisture from getting inside (inspect annually) by storing them in a cool and dry place. • Wash tanks with fresh water after every dive; never paint it. • Do not drain cylinders entirely of air - especially <10bar (except for inspections). • Do not exceed the maximum working pressure. • Do not use a dented, obviously doggy cylinder. • Avoid heating up cylinders to elevated temperatures. Hydrostatic Tests: Are performed with 5/3 of the working pressure; i.e. 350bar for a cylinder with 210bar working pressure. Tests are performed in water baths to limit the explosive character of Al-tanks (shatter by exploding in shrapnel-like manner). Steel tanks tend to peel rather than to disintegrate. Fitness of tank is measured by determining the overall expansion of the water-body into which the tank is submerged. The purpose of tank testing is obvious, as rust formation (trapped as Fe2O3) in steel tanks will reduce wall thickness of the cylinder. Al2O3 formation in Al-tanks tends to form pinholes into the tank wall; both effects reduce strength and ultimately failure while filling the tank is predetermined. Unused SCUBA tanks should be stored in a cool and dry place. To keep the water out, tanks should be filled at least with 50bars. Also while diving, never use the last bit of air in your tank, water may enter and will result in corrosion. Likewise, pony bottles for spare air have to be tested once a year as well. While hydrostatic testing is done once every 5 years, visual inspection of cylinders is done on an annual basis. If an inspection reveal corrosion, then the tank must undergo a tumbling / rumbling process with half the working pressure for several hours using abrasive material, or in severe cases must undergo sand-blasting.


Cylinder Valves and Manifolds SCUBA cylinder valves are simple, manually operated on-off valves (fig. 13.4). Valve Snorkel: it is an extended pipe stretching into the cylinder that is meant to prevent debris from entering into the 1st stage. Burst Disk: Is an overpressure valve, designed to activate when exceeding the maximum pressure limit of the tank. K-Valve: the standard on-off valve. J-Valve: cylinder valve that incorporates a low-air warning mechanism. It is an older valve system that lacks the overpressure valve, thus no longer in use. DIN Valve: a simple on-off valve with a captured O-ring. Safer than the K/J-valve designs as the O-ring is at the bottom of the socket, rather than on top of it. This reduces the likelihood of O-rings that might pop out during the filling process or during the dive itself. H-Valve or Y-Valve: a dual valve-system for deep dives allowing redundant regulator system for backup.

Fig. 13.4: The most common valve types

SCUBA Regulators Regulators are required to reduce the tanks working pressure to ambient pressure. This is done in two stages: First Stage: Reduces the tank pressure to an intermediate working pressure of 10bars above breathing pressure. Second Stage: Reduces the intermediate pressure to breathing pressure. General Design of Regulators: Reduction of the tank pressure to an intermediate pressure is brought about by a special valve; currently two types are available (fig. 13.5): (i) Upstream Valve: Opening against the airflow, this

valve type is rare in modern regulators. As cylinder pressure decreases, less ambient pressure is required to open an upstream valve. It tends to fail in the closed position interrupting air supply.

(i) Downstream Valve: This valve is configured with springs that keep the valve closed at the maximum cylinder pressure and is, therefore, more resistant to opening as cylinder pressure decreases during descent. The valve opens in the direction of the air flow, which is far safer than the above.

Fig. 13.5: Upstream versus downstream 1st stage

valve25

Operation of 1st Stage Regulators: The internal valve of the 1st stage reduces the high pressure to an intermediate air pressure. Therefore, the intermediate pressure remains at a constant level above ambient as the diver de / ascends, and is available in two configurations (fig. 13.6): (i) Balanced Valve: This type is one in which air

pressure does not affect the force needed to operate the valve. The valve operates regardless of cylinder pressure.

(i) Unbalanced Valve: Proper function of this valve type is directly affected by cylinder pressure. As the cylinder empties, it will become increasingly more difficult to breathe.

Fig. 13.6: 1st stage unbalanced and balanced

diaphragm26

For this reason, most experts recommend that scientific divers use regulators with balanced first stage valves.

25 http://www.delportdupreez.co.za/diving/equipment/html/valves.html 26 http://www.delportdupreez.co.za/diving/equipment/html/first_stage.html


Regulator 1st stages are available in 2 models: (i) Piston: This regulator model usually has fewer

moving parts than the diaphragm regulator, making servicing easier and cheaper. The unbalanced piston first stage has a bias spring, which, along with ambient pressure, balances the intermediate pressure. It opens then the diver descends or inhales (fig. 13.7).

(i) Diaphragm: It is designed so that a spring opposes the force of the cylinder pressure and acts, in conjunction with ambient pressure, against a flexible diaphragm. As the diver descents, ambient pressure increases and forces the diaphragm to bulge, causing the valve to open.

Fig. 13.7: 1st stage unbalanced and balanced piston

This allows high-pressure air to enter the chamber until equilibrium is restored (fig. 13.6). As both have some fundamental differences; these valve models can come in balanced or unbalanced configurations.

1st Stage Failure: (i) Piston: A failure in the piston seal in either type of piston 1st stage valve will cause the valve to fail in the

open position and the regulator to “free-flow”. Maintenance recommendations suggest, that the seal of the piston must always be replaced by using a plastic bullet over which the O-ring is securely slid without shaving it.

(i) Diaphragm: A failure of the diaphragm in either type of the diaphragm 1st stage valve, although rare, will cause the valve to close, shutting off air completely. Maintenance recommendations suggest that the diaphragm requires change after every 300th dive.

Regulator 1st stage care and maintenance: coloration of the filter in 1st stage provides clues about the condition of the scuba cylinders: • Greenish filter: indicates corrosion from moisture inside the tank or dripped onto the filter from outside. • Reddish filter: indicates rust from a steel tank. • Blackish filter: indicates carbon dust in the cylinder originating from a compressor. Operation of 2nd Stage Regulators: These valves are located in the mouthpiece assembly of the regulator and reduce the intermediate pressure to ambient pressure air for breathing. The 2nd stage valves are connected to the 1st stage by a low-pressure air hose (fig. 13.8). (i) Downstream: here, a reduction in pressure in the 2nd

stage chamber causes the 2nd stage diaphragm to bulge inward and depress a lever. This lever opens the valve and admits the air into the mouthpiece at ambient pressure.

(i) Upstream: this type is inherently inefficient and potentially dangerous. One of the most dangerous features regarding the build-up of pressure from the 1st stage, the valve will not free flow – it will shut off the flow of air completely!

(i) Pilot: This valve uses air pressure to open and close it instead of mechanical leverage like the downstream and upstream valve. This system, although more complex, requires only ¼th of the inhalation effort needed than the other two types.

Fig. 13.8: Regulator 2nd stage cross sections


Regulator Attachments: “Single-hose” regulators are commonly used today (one hose connects the 1st and the 2nd stages – fig. 13.9). However, high-pressure hose attachments for the submersible pressure gauge (SPG), and attachment for intermediate pressure hose for the BC inflator system, spare 2nd stage, and dry-suit inflator outlets are commonly fitted.

Fig. 13.9: Integrated 2nd stage connected to the 1st stage

via a high pressure hose Regulator 2nd stage care and maintenance: • always soak the 2nd stage chamber with warm freshwater after every use (avoid pressing the purge button); • mucus accumulation in the 2nd stage attracts cockroaches, fungi, and bacteria that will result in the

deterioration of the diaphragm (avoid the use of silicon grease); • remove mouthpiece to avoid accumulation of bacteria – especially in the socket interface where the

mouthpiece is snapped onto; Important: a spare regulator attached to the 1st stage must provide air in an emergency. This is especially important for panicking divers – don’t save for the sake of a cheap model, it supposed to be a life-saving device in an emergency situation.

Regulator concerns: when upright in water, a diver’s mouth is higher than the chest, so pressure at the mouth is slightly less than the pressure at the chest. A slight breathing resistance develops due to this negative pressure. Turning upside down, the 2nd stage delivers air at higher pressure than that on chest-level, a slight positive pressure breathing situation results. Under such conditions a poorly maintained and hard to breath regulator can result in breathing problems underwater. Due to adiabatic expansion and the drop in temperature, regulators can freeze when exposed to ice-cold water jamming the mechanical parts in the 2nd stage . Likewise, sand can interfere with the mechanical parts. Diving instruments Cylinder / Submergible Pressure Gauges (SPG): the analog version is usually made of a flattened helical sealed tube that tends to uncurl when pressurized (Bourdon movement gauge). Depth Gauges: the simplest form consists of a capillary tube that compresses in a length of clear tubing during descent (fig. 13.10). The open Bourdon tube likewise is a one-end open tube. The sealed Bourdon (oil) tube faces the ambient water pressure via a sealed rubber diaphragm. The diaphragm depth gauge works like the metal membrane barometer. A hermetically sealed and partially evacuated chamber compresses as it is exposed to ambient water pressure. Electronic SPG’s are already available and are usually integrated into the instrument console where these instruments monitor also SCUBA tank pressure. Analog vs. Digital: at altitude analog depth gauges are inaccurate. They read shallower than actual depth, and corrections must be applied to obtain an accurate reading. Most dive computers will adjust for altitude once it has been entered into the menu.

Fig. 13.10: Various types of SPG’s

Underwater Timers: a distinct advantage of a bottom timer over an underwater watch is the automatic operation (starts counting with the start of the descent). Electronic Dive Computers (EDC): several features are covered with a EDC; current and maximum depth, elapsed underwater time, surface interval, temperature, no-deco time left, ascent rate, dive number, No-fly time, etc. EDCs recalculate the dive schedule 3 minutes while dive tables assign to each dive a rectangular shaped profile. Most EDCs can be used for deco dives, however, it is recommended that they be used within the EDC’s no-deco limit.


Diving Compasses: most dive compasses are liquid filled (fig. 13.11). The bezel (rotating part) should be cleaned with fresh water as sand can block its movement. The lubber line indicates the heading direction of the diver, while the bezel is used to align the diver to the preset-path. Underwater navigation is separately covered in Chapter 15 – Navigation for Divers.

Fig. 13.11: Compass Buoyancy Compensation Device (BCD) The most common types of BCDs are horsecollar, jacket, and back inflation units. Good BCDs are equipped with a dump valve to allow rapid manual deflation. Low-pressure inflator systems use intermediate pressure air to inflate the BCD. It is controlled via a balanced valve as it is unaffected by pressure changes in the tank. When ocean diving BCD’s require internal rinsing especially as sand and dried salt can cause wear. Troubles with BCD are often related to poorly maintained equipment. The most common defects involve a stuck inflator mechanism (fig. 13.14). If this does occur underwater and to avoid a rapid ascent, the diver should immediately disconnect the inflator hose and operate the BCD orally. Ideal weighting should be tested prior of the dive by getting geared up completely and getting into the water. Ideal weighting should bring the diver to eye level, while respiration oscillates the diver from chin to forehead level.

Fig. 13.14: BCD valve mechanisms

Dry Suits The primary advantage of dry suit diving is warmth and insulation does not change with depth. It must not fit as snugly as a wet suit, and does not give the cold water “rush” when entering the water (fig. 13.15). Putting on a dry suit on often requires help from the buddy – especially when the main zipper is located at the back. Prior to a dive, excess air must be purged by squatting and momentarily opening the neck seal from the dry suit (the basic concepts and maintenance of dry suit diving are generally covered with the open water diver certificate). Dry suits are the most efficient protection for cold water diving (especially with water temperatures <10°C). Since a dry suit is filled with air it is more buoyant than a wet suit. Furthermore, any change of depth requires equalization. Some have BCD-type inflation / deflation hoses, while others have specialized inflation / deflation valves. Regardless of the type of inflation, most dry suits fill with air directly from the tank via an intermediate-pressure inflator device. Care must be taken with such suits; once the air is trapped and pooled in the legs in an upside-down position, it is easily possible to loose control. To stay warm and maintain a body surface temperature of about 25°C, thermal protective garment must be worn underneath. Many dry suits are made of neoprene too, but use a watertight zipper as well as neck and wrist seals to keep the water out. Therefore, the zippers of a dry-suit have a life expectancy of only 300 opening- and closing-cycles. Thus, every intended use must be carefully evaluated and programmed in advance.

Fig. 13.15: A wet suit traps water while a dry suit

keeps water out altogether


Air Compressors Compression is based on the principles of Boyle’s law, and results in temperature increase. The increased concentration of water in the smaller volume of air is able to remain as vapour because of the higher temperature. But as the compressed air cools, the water vapour will condense into liquid H2O. To prevent this from happening, as well as to remove possible oil vapour, the air is passed through intercoolers after each compression stage and through a desiccant in the end of the filtration system. The air in SCUBA cylinders is therefore very dry. Working Principle (fig. 13.16): 1st Stage: Brings about pressure reduction to remove the humidity contained in ambient air. Molecular sieves are used to block off water droplets from progressing further into the compression processes. 2nd to 4th Stage: actual compression takes place; with increasing stage, the piston diameter decreases to reduce stress upon the higher compression stages.

Fig. 13.16: Compressor: (1) intake valve, (2) exhaust

valve, (A-D) stage 1 to 4

Compressors do not use standard engine oil, as this results in partly oxygenated by-products (mainly CO) poisoning the compressed air in the storage tank. The commonly observed effect of dried up mucus lining in the oral cavity is due to the dried air pressed into the SCUBA tank. A ceramic moisturizer can be fitted into the intermediate pressure hose to reestablish natural humidified air. If such a device is not installed, the respiratory tract must remoisturize the inspired SCUBA air to raise its relative humidity to 100%. The moisture needed is a major cause of dehydration in divers. This should be another reminder to drink plenty of H2O before and after the dive to compensate for the loss of body fluids.


14. Deeper Diving and Technical Diving Techniques As deeper diving drastically reduces available bottom time and includes as such an increased risk potential, it is essential that the dive team knows exactly what’s going to happen, who is taking up which part of the job, and that each member of the crew can rely on the other group member’s readiness. Diving Readiness The Assumption of Risk involves a careful selection of the crew on the basis on their abilities and skills. Planing and execution a dive are the main duties of a certified diver. The ultimate goal of that procedure is to make sure that the activity undertaken underwater is safe! Self Awareness and Buddy Assessment: SELF ASSESSMENT should be in the planning of a dive in order to determine whether being fit enough to participate or not. Evaluation of a task should be done in an honest way (ask yourself if you are capable of doing this particular task, have you ever done it before?). The same principles should be applied to your buddy. Be a good buddy to yourself as well as to the dive buddy. Self evaluation and the ability in aiming at an “objective” conclusion is strongly connected to that self-assessment. Indeed, (self)discipline is “the” virtue required for a successful dive – stuck to the pre-established dive plan along with the agreements made on that basis, keep gear neatly and safely stored, and avoid making confusion. Preparing to Dive Fitness to Dive: apart from physical fitness, any diver must have a valid medical (not out of date). Contraindications that can be counterproductive to diving range from relative, absolute, temporary, sub-related contraindications (refer to Chapter 6– Diving Physiology and Fitness, for a detailed list). Taskloading: Having one’s own equipment is the most effective approach (one’s own equipment is best looked after). “Task loading” avoids stress underwater. Too much to do within a limited given time increases the likelihood of making mistakes – never overload yourself. If a deadline can’t be met than so be it. If the dive involves special skills, e.g. technical diving (Nitrox, Trimix, Overhead Environments, etc. ) it must be essential that the buddy is trained for this particular purpose as well (see end of this chapter). Training: passing vs. proficiency and power vs. mastering. The mark of a skilled diver is characterized by its ability to assemble equipment in a reasonable short time. Planning and Preparing for Successful Dives there is not substitute for advanced planning. By visiting the area, choosing the dive site well ahead of the scheduled dive, and gathering extra knowledge provides an extra safety margin for the risk assessment. Equipment preparation is essential – check and maintain dive equipment properly and beforehand but not on the weekend before departure (might be too late to get some spare parts in). The use of vinegar to remove incrustations is recommended for regulators and other submerged parts. Zippers of wetsuits can be greased with candle-wax, etc. Dive Planning: this includes establishing the maximal depth and duration of the dive as well as the calculation of the surface consumption rate (SCR – fig. 5.9, p.24) of that dive. It also includes emergency planning as part of the risk assessment. Some guidelines for planning a dive profile includes the following (fig. 14.1): i) check the dive planning mode of the dive computer. i) make sure the profile is realistically tailored to the

underwater terrain and depth. i) select a profile that is feasible, considering the air

supply and air consumption rate for both you and your buddy.

i) take an underwater slate with you, with your primary and contingency profiles written out.

i) stuck to planing and dive your plan. i) do the deepest part of the dive first, and move

progressively shallower as the dive progresses. i) allow both time and sufficient air to make a slow,

controlled ascent with safety stops. A good practice is to plan the turn-around and return to ascent point at ½ the starting cylinder pressure plus 20bar (this is of crucial importance in the case of a pressure hose leakage).

Fig. 14.1: Research Diving Workplan27

27 see Appendix, for the complete form


In order to increase effectiveness of pre-dive preparations, have a checklist ready to overlook the gadgets required for coming dive expeditions. Your First Aid Kit: only use an approved 1st aid kit and bring your O2 provider equipment (on which you have been trained) as well. U/W Signals: before commencing a dive, get all the parties together and have a briefing on emergency commands and procedures (fig. 14.2); don’t forget the buddy briefing and the dive plan coordination. A final mutual gear check should be always performed. Emergency procedure considerations: i) make sure that buddy is alert, i) bring your dive table along (to adjust for

modifications occurring during dive), i) regularly check pressure- and depth gauge; i) place deco-line and spare tank at deco-stop; i) of particular importance are the “out-of-air”

emergency commands and the “lost-buddy” procedures.

Fig. 14.2: Some underwater Sign Language (UWSL)

Reducing Common Diving Risks Judgement Problems: evaluate your personal diving fitness and manage your decisions – never follow peer pressure or the burden to meet a tightly set deadline. Regarding one’s emotional status, leave psychological ballast behind. Improper Breathing Techniques: “skip-breathing”, shallow breathing, and breath holdings are big NO-Nos. Coughing, sneezing, choking, and gagging; all these breathing methods may bring about hyperventilation and ultimately “shallow-water” blackout. Deep Diving (Planing & Execution) Personal limitations: as a SSD, never exceed 39m of depth utilizing compressed air; any work that involves deep diving activity beyond that limit requires specialized training and is not covered in this course. Personnel: a dive buddy and support personnel must be in place. The dive supervisor generally stays at the surface and supervises all aspects of the diving activity. The standby diver remains at the surface fully geared up, and ready to enter the water should the need arise. Potential Hazards: effect of increased pressure and N-narcosis, insufficient experience, increased stress; there is an increased amount of stress on divers during deep dives. Increased stress build-up can result in both mental and perceptual narrowing (if the buddy does not regularly check air- depth-gauges, and temperature, so do it for her/him). Health and fitness: persons in poor health and/or poor physical condition are generally considered to be more susceptible to the emotional and physical stress associated with diving. Stress and response to stress is easily amplified with increasing depth. Significant health problems should stop anyone from diving in the 1st place. Equipment Considerations: the appropriate exposure suit for a given dive site is essential to avoid water temperature related complications (hypothermia). Usually the temperature decreases with depth (more in freshwater environments than in marine environments (fig. 14.3) – unless ant/arctic dives or dives in temperate waters where dry-suit diving is mandatory. Depending on the size of the SCUBA cylinder, calculation of the SCR is necessary as increasing depth requires precise timing; a deeper dive involves larger tank volumes than a shallower dive. The cylinder valves configuration should then employ a double manifold attached to a twin tank air supply. Regulator performance is even more crucial in deeper dives; it must be able to cope with the intended depth range. Eventually the use of Nirox, Heliox, Trimix, etc. should be considered, when extending bottom times at these depths. Gas Management: estimating how long the air supply will last (calculation of SCR, see Chapter 4 - Diving Physics).

Fig. 14.3: Wetsuit compression


The Deep Dive Deployment: stratification of current in the area may obscure the real picture of underwater currents. Descent: in order to avoid equalization problems while descending, equalize early and often (every 0.3m). If equalization is still difficult to achieve, slightly rise back up towards the surface and equalizing with every full stretch of the arm while going down the anchor line (fig. 14.4). Apart from the regular equalization procedure (blowing into the pinched nose), equalization can be achieved by using the Toynbee manoeuvre (swallowing with the mouth and the nose closed, or yawning with closed mouth, or a combination of both); alternatively the Frenzel manoeuvre achieves equalization by contracting muscles in the mouth (while both nose and mouth are sealed) to open the Eustachian tubes and using the tongue to act as a piston pushing air up the tubes. Squeezes and blocks are indicators to abort the dive. On the Bottom: often, brief mathematical calculations help to establish for any narcotic effects of nitrogen. Ascent: stay within specified ascent rate of 15 ± 3m / min.

Fig. 14.4: Equalizing with every arm-span while

making its way down the anchor line avoid equalization problems

Safety or Decompression Stop: for the sake of extra security always perform a safety stop. Deeper dives should always supply deco-stop gear anchored at the boat, which is submerged to 5-6m beneath the surface, to provide support for eventual out of air emergencies (fig. 14.5). Exit and Post-dive Activity: upon completion of the safety stop, divers should ascend slowly to the surface. Remember, that it should take at least 30secs to ascend from the stop. Report any physiological changes to the dive supervisor, and don’t forget to drink plenty of water. A Final Word: most diving problems are preventable. As a certified SSD you must also assess, as appropriate as possible your level of training and role, the qualifications of those with whom you dive (politely suggest that an evaluation of skills and confidence must be done prior to the dive).

Fig. 14.5: Decompression station with extra cylinder

and regulator

Equipment Considerations Required Equipment: certain items are universally required for safer diving. This include buoyancy compensator, diving instruments, alternate air source, safety sausage, whistle, glow-stick, and a pocket mask for in-water EAR in 1st aid care. Specialized needs depend on the task to be performed; e.g. an anchor worm. Simple Equipment modifications of any kind can proof fatal; the equipment must be maintained and serviced by qualified personnel. Proper placement of accessories is also a prerequisite for safe diving (a dive knife attached to the inflator-hose is improper. Pre-dive inspection: often simple procedures help to verify proper maintenance of equipment; e.g. submerging a regulator with the mouthpiece facing up, should make it switch into free-flow mode. Common Equipment Problems: Equipment troubles underwater should not even occur as routine checks should have been made before the dive. If they do occur, then they are usually related to broken mask and fin straps, stuck inflator buttons at BCD, etc. Therefore, a toolbox with essential spare parts of this kind is a handy commodity (fig. 14.6).

Fig. 14.6: The toolkit with basic spare parts


Buoyancy roubles with a wet- or dry-suits can be related to inadequate fit or inappropriate choice for a particular water temperature. Water temperature may be colder at deeper depths. At such depths, a neoprene wet suit will compress, which reduces its thermal protection and buoyancy. Compensation for significant buoyancy changes will be necessary (at 30m a 5mm wet suit has an effective thickness of only 2mm with a thermal efficiency of only 20%, compared to 95% at surface level). As the wet suit compresses, buoyancy become increasingly more negative, requiring extra inflation of the BCD to compensate for the loss in buoyancy. Hypo- and hyperthermia in wetsuits are common when not familiar with a dive site or change of current modifies pre-established parameters. Pressure marks and air pockets in a drysuit can be a hazard and unnecessarily increase the risk. Musculoskeletal Problems: avoid diving related strains; use “kinetic” lifting techniques to move a full tank (remember, always keep your back straight and bend your knees). N.B.: Never lean forward to adjust your tank-fitted BCD when gearing up. Ballast Systems: simple access in a case of emergency requires a quick release mechanism (right hand release without tightening the loose end to the belt). This avoids confusion with BCD controls which are usually a left-hand release mechanism. Integrated BC and ballast systems render weight release a little bit more complicated but not impossible. N.B.: Never place an extra weight unit into the BCD pocket (risk of rolling over to one side), get back and out of the water to fix it properly! A spare pony bottle with attached regulator provides extra safety. Excessive positive buoyancy: skilled divers know their equipment and are able to adapt immediately to a given situation; e.g. the use of the dump valves to avoid bolting to the surface, rather than using the fine-tuning system at the inflator-hose. UQ-Equipment: at the University of Queensland, all the equipment provided for the SSD, are periodically checked and maintained (incl. Nitrox, full-face mask, etc.). Environmental Hazards each environment has its characteristic constellation of risk variables; e.g. clear water in pelagic ambience can easily bring about loss of orientation. Thus every environment needs to be assessed separately. Weather Related issues: temperature torments, dehydration, and sunburn are major pre- and post-dive risk factors. Always bring a hat and a long-sleeved cotton shirt (will make you about 5°C cooler than a T-shirt alone); drink plenty (at least 600mL before and after each dive to reduce likelihood of DCI). General Underwater Hazards: avoid problems from cold; temperature related troubles increase the probability of getting DCI. A tightly fitted wetsuit reduces circulation, a thick wetsuit may induce hyperthermia, which may induce seasickness when having a bumpy ride on a boat. Should it ever happen that someone has to throw up during a dive, than it should be done by avoiding that gastric juices pass through the regulator; these juices are very corrosive and trapped pre-digested food particles are an invitation for cockroaches; rather spit it out through by making a lateral opening at the edge of the mouth; as this is happening, with the regulator is still in place press the purge button to vent material off through the oral gap. N2-Narcosis can be avoided by switching to a different gas blend. Water Hazards: water density and contamination; rivers, thermoclines, altitude, and boating traffic; Natural and Artificial Hazards: entanglement, with gear (ropes, etc.) with kelp; tidal currents, rip- and longshore currents, surf diving and surge; avoid overhead environments. Overhead Environments: are those with restricted access to the surface, and include caves, caverns, wrecks, ice, etc. avoid all overhead environments unless specifically trained! An emergency ascent without open hatches in the surface above significantly increases the risk of a dive related accident. Ice Diving: apart from dry-suit outfit and tethered line ascent, the site access is of crucial importance; to avoid cracking of the surface ice, the triangular shaped entry point is least likely to break off while trying to get out of the water; the circle shaped hole does not offer any supporting angle what so ever; in the squared pattern, thinner ice is most likely to fracture making it hard to get out (fig. 14.7).

Fig. 14.7: access to ice covered water; the square hole

offers easy access but tends to break apart with thin ice; a circular access is the most stable but offers little grip;

the triangular one is considered a compromise


Technical Diving Enriched Air Nitrox (EAN) diving has become so common place in civil applications that it is no longer considered technical diving. Alternate Breathing Gases and Mixtures: the chief goal of using different inert gases is to reduce excess nitrogen loading into the diver’s body tissue. Diving with Nitrox makes working underwater safer and easier (diver feels less exhausted than by using compressed air). The most common mixtures are Nitrox and Heliox – both oxygen enriched gas sources (fig. 14.8). Nitrox courses are available (ask Noel).

Depth [m]

Compr. Air NDL

EANx 32 NDL

EANx 36 NDL

18 56 min 95 min 125 min 22 37 min 60 min 70 min 26 27 min 40 min 50 min

Fig. 14.8: Comparison of compressed air with the two most popular mixtures containing 32% (EANx32) and

36% (EANx36) O2.

Nitrox Diving: it is also called enriched air nitrogen (EAN) or O2 enriched air (OEA) as it is a blend of oxygen with air (fig. 14.9). Adding O2 to air has the advantage of reducing the percentage of N2 in the breathing gas. Because pN2 is lower, less of it is absorbed by the tissues. But there are certain trade-off’s because of the increased partial O2 pressure. Nitrox handling facilities and divers whose equipment will be exposed to gas mixtures that are higher 40% O2 must be careful to use O2 clean equipment with O2 compatible components.

Fig. 14.9: Nitrox Diving

Heliox Diving: when performing work in depths between 76 to 300m, the divers usually live in a large compressed (pressure level equivalent to depth) tank for days or even weeks at a time. The use of He has 3 major advantages: (1) it only has about 1/5th the narcotic effect of N2; only half as much volume of He dissolves in body tissues as N2; (3) He has only 1/7th of the density of N2, reducing breathing resistance. To avoid O2 toxicity, deep dives (e.g. 210m, 22bars) require only a 1% O2 mixture to provide all the O2 required by the diver; whereas using a 21% mixture achieves a pO2 of 4bars, which would result in seizures in as little as 30mins. Full-face-mask diving and u/w Voice Communication Underwater communications in the “classical sense” involves a full-face mask, underwater microphones, a transceiver and a hydrophone mounted on the divers head and a land-based system that involves a standard microphone, sound-converter and a submerged hydrophone (fig. 14.10). The system works on the principle of raising the audible spectrum into the ultrasonic spectrum and back again. Utilization of such a system is susceptible to interference by noise generated from marine life (snapper shrimps, etc.). The range of activity also depends on the water temperature - the system works best in cooler waters and declines as water temperatures rise (50m in tropical regions). Other forms of communication involve underwater slates, dive flags (blue/white codeflag α), lighting (red/white/red illuminated buoys), or specilized communication skills like ASL. The use of a communications device under water requires extra safety measures like a pony bottle with its own regulator (fig. 14.11). This is of major importance as the main unit may become non-functional, or does vent air off if the regulator becomes stuck or the face seal does not properly fit. For this purpose, two scuba cylinders are mounted on the back of a buoyancy compensator device (BCD).

Fig. 14.10: Full-face-mask and u/w communication

Fig. 14.11: Pony bottle attached to the main tank


15. Navigation for Divers Navigational Equipment for Divers For most navigational applications, a compass, watch, and depth gauge are the basic devices required. The compass is used to maintain a heading or identify a direction (see also Chapter 13 – Equipment). It can be:

i) direct type (reads 0° to 360° in a clockwise direction but lacks a bezel: 0° N; 90°=E; 180°=S; 270°=W). i) indirect type (has a north-seeking needle with numbers on a rotating bezel)

Indirect reading has the advantage that the selected bearing does not need to be remembered, the needle points directly to the actual course heading, while the libber line is pointing into the desired direction of travel. There are two basic uses of a compass, to establish a bearing to be followed (to move in a certain direction) or to determine a bearing to an object. Hand bearing compasses or compass boards (compass mounted on a slate) improve accuracy of navigation (better than SPG-integrated compasses). Compass deviation occurs when ferromagnetic objects nearby alter alignment of the needle to magnetic north. Magnetic north is the current origin of the density lines, while the true north is the geographical location with reference to the earth’s axis; e.g. Vanuatu deviates by 11° whereas Cook Islands even by as much as 90°!. A dive watch or underwater timer is useful once the time and speed of travel are known. The distance can be calculated as:

d = v⋅t v, velocity t, time

[m/s] [s]

Compass, watch and depth gauge are essential tools in navigation.

Measuring Distance Underwater Cylinder pressure is another method of approximating distance. If a diver uses 35bar of air while swimming in a given direction, the return distance will be about the same (given there is no current – fig. 15.1). Counting Kick cycles is an approximation of the distance covered. The cycle of a kick defined as a complete kick of both legs, and is usually counted when one leg reaches the top of the kicking cycle. Arm spans can be used when diving in limited visibility. It is measured with the arms extended in line with the body rather than perpendicular to the body. Measured line (tape) provides very accurate means of distance measuring. Securing one end of the line to a stationary object or buddy while the other diver unreels the line till to the desired distance. Laser leveling meter for underwater mapping yields the most accurate results; similarly to those used on land, they require stable, low current conditions as the beam originating from the base has to be reflected from the distantly placed reference pole.

Fig. 15.1: Natural navigation and air consumption

Means of Navigation Navigation can utilize natural features (coral bommie, rocks, bottom structure, etc.), instruments (compass, watch, etc.) or a combination of both (fig. 15.2). Pilotage along a rock toward a wreck and further to a bommie; (gu)estimation = dead reckoning, is another way to determine the time it takes to dive across it. Natural navigation follow features of the bottom (ripples of the sand, rocks, etc.). Sand ripples usually align parallel to the shore and become more densely spaced the closer to the shore. Sun and shadow cast can be used in clear water. Marine life zonation can be used to cover larger areas.

Fig. 15.2: Natural navigation

In compass navigation, holding on to a fixed dive pattern (parallel, triangular, rectangular, or circular – fig. 15.3) provides a straightforward approach. The bearing and time are the two key variables. Reciprocal course involves swimming against the pattern the diver came from. The circular pattern though, is the most difficult to follow and should be done with a tethered line. A square pattern is easily done by swimming the 1st leg on a heading of 0°, the 2nd on of 90°, the 3rd on 180°, and the 4th on 270°.

Fig. 15.3: Typical dive patterns; keep compass flat; this avoids jamming of the bezel to obtain a proper reading.


When the direction and distance to two or more land-based objects are known, the resulting position is known as a fix (fig. 15.4). The heading frequently uses the shoreline as a reference, so the diver will know if she/he are swimming toward or away from shore once on the bottom. Combining the above to the benefit of navigation will not only help to find the correct path, but also make sure that the diver will easily make its way back to the point of departure. Navigational Problems Obstacles and currents are the main troubles when applying underwater navigation. An obstacle can be circumnavigated by modifying the dive pattern. A current will affect the swimming speed with or against the water movement. It will result in a leeway (side-slippage) drift when swimming perpendicular to the current (fig. 15.5). This error must be taken into account when applying combined underwater navigation. Compensations for current drift should be performed. There are several ways to handle the effects of leeway drift underwater. First of all, the diver should navigate as close to the bottom as possible. Secondly the diver should navigate from object to object along a heading. If necessary, a dive should be started by swimming against the current and terminated by drifting back with the current. Measuring the strength of a current: spit into the water and measure elapsed time it takes to move past the length of the mermaid line (approx. 20m). Use of Charts Charts can be useful for diving navigation as they contain information of depths, landmarks, distances, bearings, etc. (fig. 15.6). Due to the limited range of underwater activity, information about latitude and longitude will be of little help (unless using DPV, diver propulsion vehicles). Charts for large scale underwater surveys establish position and measure distance by means of latitude (angular distance from north to south) and longitude (angular distance from east to west) of the grid-like lines on a globe that extend around horizontally at the equator and vertically from the poles. In this aspect global positioning system (GPS) is a powerful tool.

Fig. 15.4: Two sets of in-line objects to establish a fix.

Fig. 15.5: Compensating for leeway

Fig. 15.6: Underwater map of a dive site

Advanced Underwater Navigational Equipment Acoustic beacon receivers (ABR – fig. 15.7) are considered to be the most sophisticated equipment for underwater navigation are: these are small, battery-operated devices that transmit and receive a high-frequency signal when activated. A diver who is equipped with a receiver determines the direction of the beacon by slowly rotating in the water until the receiver produces an audible tone in the headset. The bearing is then noted as a changing pitch; the pitch with the highest frequency (or loudest tone) is the heading that the diver must take to find the target or origin. This device is especially for limited water visibility.

Fig. 15.7: ABR for homing in low visibility water


16. Limited Visibility and Night Diving What is Limited Visibility Diving? Underwater visibility is considered limited when one can’t see another diver at a distance of 3m or less in a horizontal direction. This represents an extra risk factor and should be included in the risk assessment. Specialized techniques must be employed to maintain buddy contact. Factors Determining Water Visibility This is primarily controlled by particles suspended in the water, by weather conditions, tidal oscillations, and the type of bottom sediment. Fine-grained sediments, like silt and clay, can be kicked up by the diver’s fins (good buoyancy is a must when confronted with such bottom substrata).

Fig. 16.1: The reel; when attached to a floating buoy, it

can be used to indicate the diver’s position during a drift dive

The presence of a thermocline, tannins (pigments from tree canopy staining the water) color the water, and plankton (passively free-floating zoo-and phyto plankton in the ocean) can remain suspended in the water column for long periods of time (plankton blooms commonly occur in spring or early summer). All these events usually result in reduced visibility. Techniques for Low Visibility Diving The most obvious concern in limited visibility diving is diver separation. Separation can be stressful to some divers, thus careful acoustic observation (bubble noise, dive-knife hitting tank, etc.) may help to re-establish contact. Sometimes rising half or a meter above the bottom may increase visibility, making buddy spotting easier. Otherwise, the diver should not look for more than 1min, but gradually make its way up to the surface. Buddy lines: when visibility is near or at zero, a floating buddy line (roughly 1m long – fig. 16.2) is essential (the holding hand option can be used if no line is available). Ideally, the line should be attached to the BCD. In any case the use of such a line introduces an additional potential entanglement hazard and should be included in the pre-dive risk assessment. Tether lines: when diving in low-visibility conditions along with a persistent current, the dive group should consider the use of a tether or lifeline. The line is securely attached to a chest belt (carabiner or bowline knot to prevent slipping) that is worn under the BCD.

Fig. 16.2: A buddy line ensures contact in limited

visibility

Keeping the line tight, the diver can be always monitored by the remaining staff members of the group stationed on the surface. Tethered dives increase jeopardy of line entanglement, and consequently, knifes must be carried and easily accessible (chest or arm-mounted knives are recommended). To establish communication with the diver, some basic signals are used and trained properly prior commencement of the dive. The use of protective gloves is beneficial, as reduced visibility does not allow a visual check of the grip. Line Signals: Line signals are made up of two different types; i) pulls; are long, steady pulls of the line; i) bells: are short, sharp tugs of the line; the duration of one pull will equal the time it takes to signal two bells.

Four pulls: Four bells:

Line Signal procedures: i) both bells and pulls should never be made violently; i) foul lines will prevent effective communications (points where line got bent or snagged); i) the dive team should keep the life line taut; i) gaining attention: all messages are preceded by 1 pull to attract attention and to stop activity; once the signal

has been answered by 1 pull, the message can be sent; i) acknowledging the signals is achieved by repeating the signal back to the originator; i) interpretation of the signals: depending on the dive plan the stage of the dive, the divers are undertaking may

have a bearing on the meaning of the signal; i) emergency pull up is signaled by a succession of more than 4 pulls.


Signals are split into general and directional signals; these signals are used in the commercial dive industry; every step and every signal is protocolled; to make sure that the diver under no circumstances is lost, the line itself is attached to the diver via a specialized chest-belt that is worn under the BCD and secured with a screw-carbine. General signals from the Attendant to the Diver: 1 pull are you OK or to gain attention; 2 pull as pre-arranged; 3 pull you have come up too far, descend till your

told stop; 4 pull come up;

Directional signals from the Attendant to the Diver: 1 pull search where you are; 2 bells go to the end of the line; 3 bells face the shot line, then go right; 4 bells face the shot line, then go left; 5 bells move towards the shot line;

General signals from the Diver to the Attendant: 1 pull gaining attention, or I am OK, I’m leaving

the bottom, I’ve reached the bottom; 2 pull as pre-arranged; 3 pull I am going down; 4 pull may I come up; >4 pull emergency signal, pull me up immediately; 2 bells I am fouled, need assistance of diver; 3 bells I’m fouled but can free myself;

Directional signals from the Diver to the Attendant: 1 pull stop; 2 bells pull up 3 bells lower; 4 bells take up slack life line; you’re holding me

too tight; 5 bells found object, started work, completed work

Orientation : entering into turbid water will quickly result in loss of orientation - which way is up or down is often the most frequent challenge the diver has to face. Using the anchor or drop line aids during the descent. As instrumental navigation under such conditions is essential, the diving team must align their compass to some surface reference prior to the descent. How to find your way in limited visibility: certain tools can and should be used to save time and energy in low-visibility under water activity; these include i) Reel and line – be trained in and practice skills regularly before entering low-visibility waters; i) Timing of trip – strictly follow pre-established timetables for the dive (to and from target site); i) Substrate references – objects, rocks, slope, etc. should be used for underwater activity; i) Currents – be aware of sudden changes in current patterns; i) Surface light – if present regularly check surface light intensity; i) Sand ripples – remember that ripples on the bottom usually align parallel to the shoreline; i) Acoustic beacon receivers – are of essential importance in murky waters when tethered dives are not possible;


Night Diving and Equipment for Night Dives Preparations: besides proper equipment maintenance and extra tools (torch, glow-stick, spare light, etc), the dive group must check the site in daylight first (spotting specific underwater landmarks)! When relying on sunlight, preparations must be completed before darkness sets on. When diving from a boat, fitting the drop line with chemical glow-stick eases the fatigue of finding the point of origin. When beach diving, the lookouter must be left with a torch to mark the location of the shore position (never use street illumination as a reference, as often these are switched off after a certain hour). All power-packs for underwater lights (rechargeables or non) must be fully powered up. Regularly test for power-capacity of rechargeable packs (Pb-gel accumulators require a 15h charge period; modern NiCd cells can be quick-charged but far to often suffer from memory effects; NiHM cells are better as the do not suffer from memory effects, can be fast-charged, but do not hold charge as long as NiCd cells; LiIon cells are the modern substitute, although expensive, they are reliable and robust). Whichever power pack is used, its advisable to include spare packs into the checklist. As night diving often comes along with a loss of orientation, resulting in vertigo, it is advisable to skip dinner or limit it to a light snack (avoid drinking orange juice and refrain from cheese-sandwiches, as these increase the likelihood of seasickness when using a boat). Keeping track of where you are: a compass is a must for night diving. Remember to align it prior to descent. Placing strobe-lights (high-intensity flashing beacons) at the site of entry aids in orientation. Equipment: dive lights are a must; the use of a pony (spare) lamp is mandatory, especially when losing the main torch or running out of energy (fig. 16.3). Battery selection is likewise important as cheap ones often expire half way through the dive. Dive light maintenance is basically limited to cleaning and greasing the O-ring system. On occasions, the torch may get flooded, should this ever happen, than remove the batteries immediately (underwater) to avoid acid reaction eating away the silver coating of the reflector. Longer lasting are LED torches that are likewise bright. Dimmable lamps are more suitable in very low visibility water (reduction of back-scatter).

Fig. 16.3: Dive lamps and glow sticks essential for low

light diving

To use a dive light most effectively, the diver should hold it to the side and above the object attempting to see, as this will minimize back-scatter of suspended particles; using a dive light requires courtesy, therefore never direct the beam directly into another diver’s face (fig. 16.4). Under limited visibility diving, a dimmable torch often provides better visual support than a fully powered up light. Another feature that should be never missed on a night dive are chemical glow sticks (attached onto the tank and activate prior to entry), strobe lights (marking the point of entry / exit), and surface lights (for entry and exit points – fig. 16.3).

Fig. 16.4: Torch signals used in a night dive; but never

shine into the buddy’s eyes! The Night Dive When to terminate a night dive? Exceeding pre-established limits on air consumption, depth, and time limits, failure of either diver’s primary light source, as well as loss of buddy or simply when suffering from hypothermic symptoms or other signs of stress. Potential hazards of night diving include disorientation, claustrophobia, entanglement, boat traffic, silt (backscatter on light), contacting hazardous species, being startled by fast swimming creatures such as seals and sea lions. All these aspects should find their way into the risk assessment. During ascent, shine with the light onto the bubbles and gauges to judge the rate of ascent! Carefully monitor for boating traffic as well as entanglement if lines are used. As for a safe termination of a night dive, have dry clothing ready and as always keep drinking plenty of water.


17. Search and Light Salvage Organization Personnel: extra staff may be required to monitor the diving activity. Coordination of the search must be assigned to the Dive Coordinator or standby diver. When more than one divers are involved in the search operation, task sharing is essential. Remember, that personnel safety has the highest priority in the search activity. If for whatever reason, the Dive Coordinator decides to abort the search operation, than the dive must be aborted. Other factors that should be taken into account regard visibility, depth, substrate composition, accessibility, currents, and all the information available regarding the search itself (gather as much info as possible, make notes about the lost object). Defining a search area: limit the search area to a reasonable size, identify any hazards (risk assessment) and select a search pattern suitable for the area. Any specialized equipment necessary for search and light salvage operation should be negatively buoyant. When working in teams, practicing a “dry run” this often highlights weak points and avoids unnecessary confusion underwater. Special Equipment: Surface markers or buoys should be used to enable easy monitoring by the Dive Coordinator. Anchors and search lines, eventually reels to mark origin of search pattern. Lift bags for recovery operations, ropes, carabiners. In some cases tools lights, tow lines, metal detectors are required to successfully complete a recovery operation. The use of gloves are recommended for rough underwater activity.

Fig. 17.1: Expanding box search pattern counting kicks

or measuring distance in meters

Risk Factors Risk-benefit assessment: is it worth while retrieving it when facing strong currents, contaminated waters, etc.? Entanglement: besides good buddy communications, good line handling techniques are mandatory. Physical injury: when relying on touch, the risk of cutting oneself is greatly increased – besides slow and systematic movements, sturdy protection is therefore essential. Loss of ascent control: great care must be applied when lifting heavy objects or moving an object in flotation, as loss of the object suddenly changes buoyancy when holding onto it. Dive crew must be able to control and use the dump valve of a lift bag properly. Laws and regulation: Currently lost items belong to the owner of the vessel or the insurance company. The UN intends to ban all wreck diving – applies also to any item that has been lost, including scientific instruments. Other risk factors include: loss of control in current, loss of buddy, etc. As with every dive, establish emergency procedures prior to diving activity. Search Patterns All search patterns involve measuring distance. This can be done by counting kick-cycles, or by using a line with proper markings, preferably reading in meters (Fig. 17.1). The contour search: swim up and down the depth contours (similar to isobaric pressure lines – fig. 17.2) until you bump into the searched item. Start with the deeper end first, and gradually making the way up the depth gradient until reaching the shallowest section of the search pattern. The distance between sweeps is only determined by underwater visibility and the size of the object.

Fig. 17.2: Contour search pattern


Compass-controlled patterns: fairly precise and accurate results may be obtained using a compass and counting kicks. The compass search is conducted by swimming on a fixed compass heading for a given distance. There are several methods to conduct a compass search; the most commonly used techniques involve the parallel search pattern and the expanding box pattern. Semi- / circular search: one end of the positively buoyant line is secured firmly in the center of the area (or hold at the surface when performing a tethered semi-circular search pattern – fig. 17.3). For the circular search it is advisable to use a descending line that is attached to a Pb-weight keeping the center of the search pattern fixed. Every time the diver completes a full circle, the reel is unwound by a certain amount (dependent on underwater visibility and size of object looked for). In semi-circular search, the land-based operator releases the line upon the diver’s request (e.g. 2 bells). Both patterns are especially suitable for muddy environments with no major obstacles where it is required to stir up the substrate to feel it; Manta tow, Straight Line search and Jackstay search pattern: with the manta tow, a diver or snorkeller is pulled along on a planing board or tow bar behind a slowly moving boat (fig. 17.4). A method applicable in good underwater visibility and to cover large areas. Communication is established via a secondary line or per full-face mask diving. When doing a straight line or Jackstay search, a negatively buoyant line is strung between two reference points (e.g. Pb-weights; fig. 17.5). These reference points themselves are marked with buoys to enable easy monitoring from the lookout staff. The search itself is conducted along the line. When a larger area must be covered, the terminals are moved in a particular fashion - moving floodlines at the edges; i.e. moving it as one proceeds (direction change); gives good accuracy and reference. Snagline search: utilizes a negatively buoyant line towed by 2 divers as they swim across the area until the lost and fairly large object snags into it.

Fig. 17.3: Circular and semi-circular search pattern

Fig. 17.4: Manta tow

Fig. 17.5: Jackstay search pattern


Light Salvage Procedures Requirements for safe light salvage: once the object has been found, it can be recovered. If it is too big, additional equipment is required to lift it from the bottom. Special skills involve knot tying and rigging skills, ability to estimate / calculate the correct size of the lift bag as well as the required amount of compressed air, and proper training to lift the item without putting the safety of the buddy / fellow divers at risk. Lift bags: it is a common device to raise sunken objects from the bottom (fig. 17.6). Upon securely attaching an object, air is added to the lift bag, displacing water and eventually counterbalancing the in-water weight of the submerged object. The lift bag together with the object start to rise to the surface. Types of lift bags: good quality lift bags enable inflation with inflator hose and have a dump-valve at the top. This is especially important when lifting objects from muddy substrates as extra lifting force is required to overcome the suction effect of the substrate resisting the lift. Subsequent acceleration and bolting to the surface can be stopped by moderately pulling the dump valve. Refrain from using open bottom style lift bags, as these are unsafe to use.

Fig. 17.6: Pillow type lift bag good for raising

weight up to 50kg and over

Controlling a lift: the amount of air placed and kept in the lift bag must not exceed the weight of the object to be lifted by a great deal (capacity of lift bag should match the weight of the object to be lifted). Careful manipulation of the inflator hose and the dump valve should make object neutrally buoyant. Never stay on top or below a lift bag, as a bolting lift bag may rocket to the surface, while a dislaunched lifted object may rapidly sink back to the surface injuring the diver below. A final word: never pick up objects by using the diver’s own BCD as a lift bag. If for some reason the diver must drop the object, an uncontrolled buoyant ascent is the likely result. Lift example: a diving crew was offered a job to recover a sunken outboard motor. It rests in 11m of salt water, weighs 45kg on land, and displaces about 14L of water when submerged. The provided lift bag is capable of holding 140L and an extra 20L bottle (filled at 210 bar) available to fill the bag with. How much air ( surface equivalent) will be needed to make the motor neutrally buoyant?

Buoyant force: 14 L

1 ⋅ 1.025 kg 1 L

= 14.35kg

In water weight: 45kg – 14.35kg = 30.65kg

Volume of air at sealevel:

30.65 kg 1 L ⋅ __1L__

1.025kg = 29.9L

p1 = (11m ⋅ 0.1ATM/m) + 1ATM = 2.1 ATM at 11m p1⋅V1 = p2⋅V2 V2 = p1⋅V1

p2

= 2.1ATM⋅29.9L 1 ATM

= 60L air at sea level

Knots Of the 2000 different known knot varieties, some 9 different types are of essential importance (fig. 17.7). Knowing which knot to tie for a proper application is the key to successfully attach a vessel to a mooring buoy or lift an object from the bottom. Figure 8 knot: used to prevent a line from unlaying or running through a block; will not jam. Bowline: makes a temporary eye in a line. Might be used as a temporary substitute for an eye-splice in mooring lines. One of the strongest, practical and useful knots. Square (reef) knot: a quick way to join 2 ends. Is secure only if the lines are the same in size and the knot is pressing against something, such as the rolled part of a reefed sail. May “capsize” and come apart under strain if not supported. Becket (sheet) bend: used to join 2 ends when knot must stand alone in “mid-air”. Will work with lines of different size. Round turn and 2 half hitches: quick way to make a fast knot against anything of any shape. Remains secure with or without strain from any direction. Can jam and be difficult to untie. Clove hitch: quick to make and will not jam. Secure when made around cylindrical objects and strain remains steady, but can loosen if standing part goes slack or strain comes from varying directions. Rolling hitch: quick, secure, and adjustable. Knot can be slid along spar or line without loosening. Bowline on a bight: handy if requiring an eye but the ends are not available. Sheepshank: used to take up excess slack or to strengthen a weak spot in a line. Will hold if very carefully made and strain is absolutely steady. When a line is cut, it tends to unravel. “whipping” is twine that is wrapped around the end of a line to keep it from unravelling.


Fig. 17.7: Standards knots

Scientific Scuba Diver Manual (AS/NZS 2299.2:2002) 103/123 Appendix

Appendix Diver Registration Form


Daily Diving and Boating Safety Record


Research Dive Operation Record Form Details of every dive for each diver must be recorded on this form DURING THE DIVE by the surface Dive Attendant. At the end of a trip the form must be signed off by the Dive Coordinator, and submitted to the University Diving Officer before another dive id permitted. Where more than one dive is done by a diver on a trip, please record the dives subsequently on one Dive Record Form.

NB: any dive after a surface interval of >15min must be deemed a new dive: Site/s: ......................................................................................................................................................................... Name of Diver: ......................................................................................................................................................... Dive Coordinator/s: ...................................................................................................................................................

Standby Diver/s: ............................................................

O2 cylinder pressure at start of day: .......................[bar]

Day & Date: ................ / ....... / ....... Dive-#: ................

Attendant: ......................................................................

Start Dive RF: .................. SCUBA pTank: ..............[bar] EANx O2: ..........[%]

End Dive PG: .................. SCUBA pTank: ..............[bar] Maximum DepthOperating (MOD): ..................[m]

Date

SI(since last dive) [hours:min]

tIn [hours:min]

tOut [hours:min]

dmax [m]

Σt [min]

tDeco / dDeco [min] / [m]

..... / ..... / .......

/

Dive Profile (please record time of each ascent to surface, and subsequent descent):

....

[min]

.... [min]

.... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

Residual N2 Time:

Effective Bottom Time:

Previous Dive No-Deco Limit Repetitive Dive No-Deco Limit

......................................................... ∆t Actual Bottom Time

..............................................…....... Σt

.......... [min]

.......... [min]

.......... [min]

.......... [min]

.......... [min] > > >

1st minus 2nd

3rd + 4th

PG: ...........

Standby Diver/s: ............................................................


Day & Date: ................ / ....... / ....... Dive-#: ................

Attendant: ......................................................................



Date


tIn [hours:min]

tOut [hours:min]

dmax [m]

Σt [min]


..... / ..... / .......

/


....

[min]

.... [min]

.... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

Residual N2 Time:




.............................................…....... Σt

.......... [min]

.......... [min]

.......... [min]

.......... [min]

.......... [min] > > >

1st minus 2nd

3rd + 4th

PG: ...........


Please see over Standby Diver/s: ............................................................


Day & Date: ................ / ....... / ....... Dive-#: ................

Attendant: ......................................................................



Date


tIn [hours:min]

tOut [hours:min]

dmax [m]

Σt [min]


..... / ..... / .......

/


....

[min]

.... [min]

.... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

Residual N2 Time:




.............................................…....... Σt

.......... [min]

.......... [min]

.......... [min]

.......... [min]

.......... [min] > > >

1st minus 2nd

3rd + 4th

PG: ...........

Standby Diver/s: ............................................................


Day & Date: ................ / ....... / ....... Dive-#: ................

Attendant: ......................................................................



Date


tIn [hours:min]

tOut [hours:min]

dmax [m]

Σt [min]


..... / ..... / .......

/


....

[min]

.... [min]

.... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

.... [min] .... [min]

Residual N2 Time:




..............................................…....... Σt

.......... [min]

.......... [min]

.......... [min]

.......... [min]

.......... [min] > > >

1st minus 2nd

3rd + 4th

PG: ...........

Diver’s / Dive Coordinator’s Comments: .................................................................................................................. .................................................................................................................................................................................... Dive Coordinator’s Signature: ......................................................................

Date: .............. / ............. / ..............

BDO or SDO HIRS Signature: ..................................................................... Date: .............. / ............. / ..............


Comments: ................................................................................................................................................................

....................................................................................................................................................................................


Record of RISK ASSESSMENT form (1/4) Date and Time of Assessment

Monday Month Year Tuesday January July 2001 2007

Wednesday February August 2002 2008 Thursday March September 2003 2009 Friday April October 2004 2010 Saturday May November 2005 2012 Sunday June December 2006 2013

Type of Diving Work being undertaken: ................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... Diving Platform (Boat, Shore, Pontoon, etc.): .......................................................................................................... Site Location: ............................................................................................................................................................. Name of Person conducting risk assessment: ............................................................................................................ Name of divers participating in underwater diving work: ......................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... Names of all other persons involved in the work and their role: ............................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... Notes: ........................................................................................................................................................................ .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... Legend: Assessed consequences: Mj - major; Md - moderate; Mn - minor; In - insignificant

Assessed likelihood: Ac - almost certain; L - likely; P - possible; U - unlikely; R - rare; Assessed risk: Ac - almost certain; L - likely; M - moderate; U - unlikely; R - rare;

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ENVIRONMENTAL CONDITIONS (cont’d, 2/4)

Assessed Risk after Control

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

TASK RELATED CONDITIONS


Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Risk Control

Risk Control

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Assessed Consequences

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In


Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Identified Hazard

Strength and Direction of Wind (Consider Emergency Response)

Current and Tide

Underwater Visibility

Entrapment Hazard

Depth of Worksite

Water Temperature

Time of Day

Underwater Terrain

Atmospheric Temperature & Humidity

Contaminants

Isolation of Dive Site

Identified Hazard (Consider complexity, non-routine nature of task)

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HYPERBARIC / PHYSIOLOGICAL HAZARD (cont’d, 3/4)


Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

ASSOCIATED ACTIVITIES HAZARD


Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Risk Control

Risk Control

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R


Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In


Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Identified Hazard

Frequency of Diving, including repetitive diving, multi-day diving

Depth of Dive

Duration of Dive

Breathing gas

Exertion required to reach dive site

Exertion required to conduct dive

Excessive niose

Immediate pre-dive fitness

Excessive noise

Immediate Pre-dive fitness

Altitude exposure

Identified Hazard

Manual handling

Boat handling

Dive site entry

Dive site egress

Crane / winch operations

Rigging

Topside plant

Dive platform

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OTHER HAZARDS (cont’d, 4/4)


Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

TASK RELATED CONDITIONS


Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Date ...... / ...... / ......

...... / ...... / ......

...... / ...... / ......

...... / ...... / ......

...... / ...... / ......

...... / ...... / ......

Risk Control

Risk Control

Signature (have acknowledged & understood this record)

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Risk

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Ac L M U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Assessed Likelihood

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Ac L P U R

Name of Participants (must read, acknowledge, & understand before dive commences)


Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In


Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Mj Md Mn In

Identified Hazard

Dangerous marine animals

Non-associated boat traffic (small craft)

Shipping movements

Water inlets

Water outfalls

Water pressure differentials

Use of hazardous substances

Existing in-water chemical pollutants

Existing in-water biological pollutants

Explosives

Hazards peculiar to dive site

Identified Hazard (Consider what is required for searching, recovery, 1st aid, and evacuation)

Location and availability of emergency personnel

Location and availability of emergency equipment

Emergency response procedures (incl. comms)

Standby diver / buddy

Alternate air supplies


Scientific Divers Log Book (1/1)


Research Diving Workplan Form (1/1) To be filled out by the Dive Leader at the dive site and supplied to the Dive Safety Committee as soon as practicable on completion of dive operation Checklist Yes No n/a If ‘No’ detail add. control measures

Copy of Diving Safety Manual Risk assessment documented? Shore contact engaged ?

Equipment check

Fins, Mask and snorkel Weight belt and wetsuit Buoyancy control device Regulator and Alternate air source Submersible pressure gauge Timing device Surface signalling device Cylinders in test Cylinder contents gauge

Surface conditions

Sea state-calm to slight? Wind less than 15 knots? Water temperature acceptable? Weather fine?

Underwater conditions

Visibility more than 5 metres? Current less than 1 knot? Depth within diving limits? Bottom conditions safe?

Communications

Radio functional? Telephone Emergency signals Diving flag “Code A” Diver recall defined?

Vessel Checks

Engine Sufficient fuel? Safety equipment Navigation lights

Divers Required number Log books

First Aid Qualified personnel First aid kit and manual Resuscitator Sufficient oxygen

Medivac Contingencies

Air Sea Rescue Ambulance 000 Diver Emergency Service 1800 088 200 Doctor/Hospital

Pre-Dive Brief

Underwater communications

Dive plan outlined Tasks outlined Hazards outlined Pre-dive function tests


Rapid field Neuro Exam Record (1/1) Diver’s Name: .......................................... Name of Examiner: ...................................... Date: ........... / ...... / ........ Initial Complaint: ....................................................................................................................................................... ....................................................................................................................................................................................

Time of Record ....... : ....... ....... : ....... ....... : ....... ....... : ....... ....... : ....... Yes No Yes No Yes No Yes No Yes No Mental Status: 1. Her / his name: 2. Where is she / he 3. Time of day 4. Most recent activity 5. Speech clear, correct Sight: 1. Correct finger count 2. Vision clear Eye Movement: 1. move all 4 directions 2. Nystagmus absent* Facial Movements: 1. Teeth clench (ok) 2. Able to wrinkle forehead 3. Tongue moves all directions 4. Symmetrical smile Head / shoulder movements: 1. “Adams apple” movement 2. Shoulder shrug normal (equal) 3. Head movements normal (equal) Hearing: 1. Normal for that diver 2. Equal for both ears Sensations (present, normal and symmetrical across): 1. Face 2. Chest 3. Abdomen 4. Arms (front) 5. Hands 6. Legs (front) 7. Feet 8. Back 9. Arms (back) 10. Buttocks 11. Legs (back) Muscle Tone (present, normal and symmetrical for): 1. Arms 2. Legs 3. Hand grips 4. Feet Balance and Coordination: 1. Romberg (ok) 2. Pulse 3. Respiration (*) Nystagmus - involuntary oscillation of the eyeball, usually lateral but sometimes rotary or vertical


Compressed Gas Treatment (1/1) Diver’s Name: .................................................................. Age: ...................[years] Date: ................. / ...... / ........ Address: ........................................................................................................Telephone: ......................................... Initial Symptoms: .................................................................................................................................................... Main Complaint: ....................................................................................................................................................... Time of symptom onset: ............................................... Time of symptom reporting: ............................................. Baseline rapid field neuro-exam: Normal: Yes / No Abnormal: Yes / No Copy with diver: Yes / No Diver Information (attach detailed dive profiles if possible): Single dive: ................... Repetitive dive: ................... Single day dive: ................... Multi day dive: .................... Number of dives in the last 24hrs: ..........................[-] Total number of dives for the last week: ........................[-] Exceeded Divetable: Yes / No Any Deco-dives: Yes / No Gas mixture used: ............................... Problems with dive (i.e. equipment or buoyancy problems, cold, heavy surge, current, out of air, rapid ascent, etc.): Treatment given: Oxygen (O2): Yes / No

Demand valve: Constant flow valve: Pocket Mask: Flowrate: ..............[L/min]

Start Time: End Time:

Fluids (intake and output):

Comments

Oral: Volume: .............[L] Type: Intravenous: Volume: .............[L] Type: Gauge: Flowrate..............[L/h] Intravenous Site: Volume: .............[L] Urinary output: Volume: .............[L] Vomiting: Yes / No Positioning:

Comments

Supine: Legs elevated: Yes / No Tolerates pos.: Yes / No If not explain why: Transportation :

Comments

Ground: Air: Type of craft: Sea: Type of craft: By who: Tolerated: Yes / No Taken to: Reports sent: Yes / No

Signature:

Note: a copy of this form is to accompany the injured diver and a copy is to remain with the Dive Supervisor’s log


Information required when completing a workplace injury form (1/2)

When completed, return the white copy of this form (pages 2 & 3) to the OH& S Unit.

Details of person injured or involved (to be filled in by person injured/involved if possible) Victim’s Name: ...................................................... Sex: F / M . Age: .........[years] DOB: ............... / ...... / ........ Address: ........................................................................................................Telephone: .......................................... Blood type: ............. RH: Pos. / Neg. Medical, religious objections to blood transfusions: Y / N Allergies or reactions to medication: ......................................................................................................................... Student ID: ........................... Supervisor / Employer: ....................... Superv. / Employer’s Phone....................... Event details: Report compiled at (loco): .......................................................................................... Date: ................ / ...... / ........ Location where accident occurred: ............................................................................................ Time: ........ : ........ If available Room-#: ................. Building: ................Campus: ................................................................................ Activity at time of the event (on duty, meal, break, travel to-from, other): ............................................................... Description / history of accident (task being performed): ......................................................................................... ..................................................................................................................................................................................... .................................................................................................................................................................................... Injury details: . Nature of type Body part (please mark the injured part(s)) Agent of damage Amputation Animal or insect Asphyxiation Biological Bruise or crushing Chemical Burn or scald Electricity Concussion Equipment or tool - powered Cut or open wound - not powered Dislocation Explos. / implos. (pressure) Exposure Muscular effort - single event Foreign body - repetitive or postural Fracture Needle or sharp object Heart or circulatory

condition Noise

Infectious disease Psychological Inhalation Radiation Internal injury Slip, trip or fall CNS injury / disorder Stepping on / striking object Poisoning Struck (falling/moving) object Puncture Other Thermal (heat or cold) Respiratory (inhalation) Teeth Vehicle Skin disorder Brain Vibration Sprain or strain Organ (specify) Other (specify) Other (specify) Medical treatment obtained: Nil: ........ 1st aid: ........ Uni Health Service: ........ Other doctor: ........ Hospital: ........ Hospital admitted: ........ Outcome of injured person: Time lost (days & hours): ........ / ........ Not yet returned: ........

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Information required when completing a workplace injury form (cont’d, 2/2) 1st aider’s assessment: ................................................................................................................................................ ..................................................................................................................................................................................... Victim’s response: ..................... Respiration:........................................Pulse taken at regular intervals: Y / N Observed injuries: ...................................................................................................................................................... Details of 1st aid provided: ......................................................................................................................................... .................................................................................................................................................................................... Referrals advised (e.g. GP, hospital, ambulance)*: .................................................................................................. .................................................................................................................................................................................... *whether this should be sought immediately or later if problems persist / arise.

Contact & Emergency Information Phone number Contact person Out of Campus contact details

Ambulance: ..........

Fire Brigade: ..........

Police: ..........

Water police: ..........

Marine Rescue: ..........

Closest Hyperbaric Chamber: ..........

Person to be notified (relatives): ...........

Poisoning hotline: ..........

........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ...........................................

........................................... ...........................................

University details

All emergencies (University): ..........

Boating & Diving Officer: ..........

Centre of Marine Studies Reception (secretary): ..........

Research Station Staff: ..........

Occ. Workplace Health & Safety: ..........

.................................. (other): ..........

........................................... ........................................... ........................................... ........................................... ........................................... ...........................................

........................................... ........................................... ........................................... ........................................... ........................................... ...........................................

Divers DAN emergency details

DAN (contact number): ..........

DAN (membership number): ..........

........................................... ...........................................

...........................................


Dive Medical Form (1/5)

SCUBA DIVING MEDICAL CERTIFICATION

This is to certify that I have examined: Name of patient: ......................................................................... Address: ..................................................................................................................................................................... In accordance with the requirements of the Australian Standard AS2299.2, and have found him / her to be:

FIT Temporarily UNFIT Permanently UNFIT for diving and diving training undertaken using compressed air underwater. Reason: ...................................................................................................................................................................... Note: Medicare benefits refund and / or medicare rebate is not permissible, by law, for this examination. No item number is issued for this medical examination. Signature: ............................................................................ Date: ......................................................................... -------------------------------------- Please detach (medical record kept with doctor) -------------------------------------- Name of patient: ........................................................................................................................................................ Medical examination (to be completed by an approved medical practitioner):

Height

.......... [m]

Weight

..........[kg]

Visual Acuity R6/ ............ corrected 6/ ........... L6/ ............ corrected 6/ ............

Blood Pressure

.......... [mmHg]

Pulse

.......... [b/s] Urinalysis

Albumen Glucose:

........[mg/mL] ........[mg/mL]

Respiratory function test (measured by equipment capable of reading to 7L)

Vital capacity [L] ............... FEV1:..........[L] Percentage:

Chest X-Ray identified Date: ........ / ........ / ........ Place: ............................. Result: ...........................

Audiometry (air conduction) results: Frequency [Hz] 500 1000 2000 4000 6000 8000 Loss in [dB] R Loss in [dB] L

If abnormal enter in diver’s logbook and on certificate The patients audiogram was NORMAL / ABNORMAL Clinical examination / assessment (normal / abnormal) N AN N AN Nose, septum, airway Mouth, throat, teeth, bite External auditory canal Tympanic membrane Middle ear auto-inflamation Abdomen Chest hyperventilation Cardiac ausulation Neurological: Eye movements Pupillary reflexes Limb reflexes Finger-nose contact Sharpened Romberg Other abnormalities

FIT Temporarily UNFIT Permanently UNFIT Comments: ................................................................................................................................................................. .....................................................................................................................................................................................

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Dive Medical Form (continued 2/5)

Statement of Health for Research Diving This section to be completed by the Medical Practitioner. This is to certify that I have today interviewed and examined: Name: ......................................................................................................................................................................... Address: ..................................................................................................................................................................... Date of birth: ................ / ...................... / ......................... Initial those statements that do and delete those that do note apply: ..................... I have assessed the candidate in accordance with AS2299 ..................... I can find no conditions which are incompaticle with compressed gas, self contained breathing

apparatus (SCUBA) and surface supplied breathing apparatus (SSBA). ..................... I have explained the potential health risks of diving to the candidate and we have discussed how

these risks may be reduced. The candidate appears to have a good understanding of these risks. ..................... Based upon my assessment, the candidate should not dive with compressed gases (SCUBA /

SSBA). ..................... Based upon my assessment, the candidate should not breath-hold dive. ................................................................ .......................................................... ............. / ............ / .............. (Signature of Medical Practitioner) (Name of Medical Practitioner) (Date) This section to be completed by the Candidate. Initial those statements that do and delete those that do note apply: ..................... I understand the health risks that I may encounter in diving and how these risks may be reduced. ..................... I also understand the Medical Practitioner’s recommendation herewith is based, in part, upon the

disclosure of my medical history. ..................... I agree to accept any responsibility and liability for health risks associated with my participation in

underwater diving, including those that are due to or are influenced by a change in my health and or failure to disclose any existing or past health condition to the Medical Practitioner.

................................................................ .......................................................... ............. / ............ / .............. (Signature of Candidate) (Name of Candidate) (Date)

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Dive Medical Form (continued 3/5)

Brisbane Orthopaedic & Sports Medicine Centre Title .................... (Mr. Mrs, Ms, Miss or other) Sex: .............................................. Name ............................................................................. Surname: .......................................................................... Postal Address: .......................................................................................................................................................... ............................................................................................................................ Post Code...................................... Phone work: .................................................................. Phone home: ..................................................................... Mobile Phone: .............................................................. Email: ................................................................................ D.O.B.: ......................................................................... Occupation: ....................................................................... Medicare Card No.: ...................... Is this claim work cover? ........... if yes, workcover claim No: ....................... Referred by: ............................................................................................................................................................... Sports involvement (include area of sport, and position played: .............................................................................. .................................................................................................................................................................................... Sports related injury? ...........if yes, date of injury: .......... / .......... / .......... List the most significant injuries: ...... .................................................................................................................................................................................... What is your current injury / medical problems? ...................................................................................................... List any medications you are on: ............................................................................................................................... .................................................................................................................................................................................... Do you have any allergies:? .............. if yes, please list: .......................................................................................... Have you had any reactions to drugs, medicines or foods? .............. if yes, please list: .......................................... Do you smoke? ............. Do you drink alcohol? ............. if yes, how many drinks a week? ................................. Do you have a regular general practitioner? ........... if yes, name: ........................................................................... Address: ................................................................................................................................................................... Do you have any objection to a letter being sent to your GP regarding your sports medicine management? .........

Have you ever had or do you have any of the following? Please tick Yes or No. Y N Y N Previous diving medical Prescription glasses Contact lenses Eye or visual problems Hay fever Sinusitis Other nose or throat problems Dentures / plates etc. Recent dental procedures Deafness or ringing noises in ear(s) Discharging ears or other infections Operation on ears Giddiness or loss of balance Severe motion sickness Seasickness medication Problems when flying in aircraft

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Dive Medical Form (continued 4/5) Y N Y N Severe or frequent headaches Migraine Fainting or blackouts Convulsions, fits or epilepsy Unconsciousness Concussion or head injury Sleep walking Severe depression Claustrophobia Mental illness Heart disease Abnormal blood test ECG (heart racing) Consciousness of your heart beat High blood pressure Rheumatic fever Discomfort in your chest with exertion Short of breath on exertion Bronchitis or pneumonia Pleurisy or severe chest pain Coughing up phlegm or blood Chronic or persistent cough TB Pneumothorax (collapsed lung) Frequent chest colds Asthma or wheezing Use a puffer Other chest complaint Operation on chest, lungs, or heart Indigestion, peptic ulcer, or acid reflux Vomiting blood (red or black motions) Recurrent vomiting or diarrhoea Jaundice, hepatitis or liver disease Malaria or other tropical disease Sever loss of weight Hernia or rupture Major joint or back injury Limitation of movement Fractures (broken bones) Paralysis or muscle weakness Kidney or bladder disease (cystitis) Any chronic disease (see note below) Syphilis Diabetes Blood disease or bleeding problem Skin disease Contagious disease Operations In hospital for any reason Life insurance rejected A job / license refused on medical grounds Unable to work for medical reasons An invalid person Other illness, injury, or medical conditions Have any blood relations had: Heart disease Asthma or chest disease TB Females only: Are you now pregnant or planning to be? Have any incapacity during periods? Previous Diving Experience: Can you swim? Any problems during / after swimming? Have you ever had to be rescued? Do you snorkel dive regularly? Have you tried scuba diving before? Have you had formal scuba training? Diving History : Year of formal SCUBA training [year]? Approximate number of dives [-] Maximum depth of any dive [m]? Longest duration of any dive [min]? Date of most recent chest X-ray: .............. / ............... / .............. I certify that the above information is true and complete to the best of my knowledge and I hereby authorize Dr. ..................... to give medical opinion as to my fitness, or temporary or permanent unfitness to dive to my diving instructor. I also authorize her / him to obtain or supply medical information regarding me to other doctors as may be necessary for medical purposes in my personal interest. ................................................................ .......................................................... ............. / ............ / .............. (Signature of Candidate) (Name of Candidate) (Date) Note: any chronic disease, such as hepatitis A, B, AIDS or tuberculosis (TB), may increase your risk from diving. If you have a chronic disease please discuss it with the doctor who will then be able to advise you wether you will be at increased risk.

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Dive Medical Form (continued 5/5) Privacy in our medical practice: We value the doctor-patient relationship. Patient privacy is vital to such a relationship. The Privacy Act 1988 and its recent amendments formalize the already existing and acknowledged privacy obligations of our practice. Our doctors and staff collect information from patients primarily to provide proper care and treatment. We have a legal and ethical duty to protect patient information. Patient information may have to be disclosed to other doctors, nurses, therapists, and health care providers and health administration services, so that proper health care is not compromised. The doctors in this practice are members of various medical and professional bodies including medical defense organizations. These organizations provide valuable services to their members. They require their members to provide information in relation to their medical practice, which may include patient information. This general patient information is used for, • Administrative purposes in running our medical practice. • Billing purposes, including compliance with Medicare and Health Insurance Commission requirements. • To other medical practitioners, hospital or health service providers including locums to assist in current or

future treatments that release to the condition you are currently being treated for; or subsequently arise, as either on outpatient or inpatient.

• Disclosure to medical defense organizations. Access to your personal information: If you wish to access health information from this practice you can collect and complete on request and after discussion with your treating doctor, a “Request for Access Form” except where access is legitimately withheld. I understand that I will be given an explanation in these circumstances. If you require a copy of your personal information a fee will be payable. I have read the information above and understand the reasons why my information must be collected. I am also aware that this practice has a privacy policy on handling patient information. I understand that I am nor obliged to provide any information requested of me, but that my failure to do so might compromise the quality of the health care and treatment given to me. I understand that my information is to be used for any other purpose other than set out above, my further consent will be obtained. I consent to the handling of my information by this practice for the purpose set out above, subject to any limitations on access or disclosure that I notify this practice of. ................................................................ .......................................................... ............. / ............ / .............. (Signature of Candidate) (Name of Candidate) (Date)


References Auerbach PS () Wilderness medicine, 5th ed. Mosby, Elsevier, Philadelphia (PA) - USA Chang R. 1994; Chemistry 5th ed.; MacGraw-Hill; Hightstown, (NJ) - USA Community First Aid & Safety 1993; American Red Cross; Mosby Lifeline; St.Lois MO - USA Guyton A.C., Hall J.E., 1996; Medical Physiology, 9th ed.; W.B. Saunders Company; Philadelphia (PA) - USA Randall D., Burggren W., French K., 1997; Eckert Animal Physiology - Mechanisms and Adaptations, 4th ed.;

W.H. Freeman and Co.; New York NY - USA Lawrence M. 1997; Scuba Diving explained - Questions and Answers on Physiology and Medical Aspects of

Scuba Diving; Cleveland (OH) - USA http://www.mtsinai.org/pulmonary/books/scuba/welcome.htm

Lippmann J., Natoli D. 2000; First Aid & Emergency Care, 2nd ed.; Submariner Publications, Ashburton VIC - AUS

Lippmann J. 2001; Oxygen First Aid; Submariner Publications, Ashburton VIC - AUS Hecht E., 1994; Physics Algebra/Trig; Brooks/Cole Publ. Company; Pacific Groove (CA) - USA Heine J., Bookspan J., Oliver P. 2000; NAUI Master SCUBA Diver; National Association of Underwater

Instructors; USA Marsh L., Slack-Smith S., Sea Stingers and other venomous and poisonous marine invertebrates of WA; Western

Australian Museum, Perth WA - AUS PADI Open Water Diver Manual 1995; PADI International; St. Ana CA - USA PADI Adventures in Diving - Advanced Training for Open Water Divers, 1991; PADI International; St. Ana CA

- USA Tortora G.J., Grabowski S.R. 1996; Principles of Anatomy and Physiology, 8th ed., Addison Wesley Longman

Inc.; Menlo Park CA - USA Food pyramid nutritional info: https://news.cornell.edu/stories/1998/01/vegetarian-diet-pyramid-released Allergies: http://195.185.214.164/rehabuch/englisch/p010.htm Full face mask diving: http://www.adp.fsu.edu/courses/FullFaceMask/

http://www.kirbymorgan.com/products/exo.html http://www.divebooty.co.uk/equipment_details.asp?pid=1076

First aid: http://www.firstaidpak.com/safetytips.htm http://www.healthatoz.com/healthatoz/Atoz/ency/decompression_sickness.html http://www.marinemedical.com/articles/diving.htm http://www.hyperchamber.com/decompression_illness/ http://www.emsmagazine.com/articles/emsarts/squeeze.html http://www.emedicine.com/derm/topic793.htm http://www.diversalertnetwork.org/medical/articles/index.asp http://www.vnh.org/FirstAidForSoldiers/Fm211_2.html#REF31h3

Trimix: http://www.cisatlantic.com/trimix/aquacorps/mix/MixBox.htm Rebreather: http://tecrec-diving.com/english/draeger_dolphin.htm

http://www.frogdiver.com/scrubber.html http://www.hypoxictent.com/co2scrubbingfacts.html http://www.metacut.com/rebreathers/glossary.htm

ASL: http://deafness.about.com/library/signglossary/blsignglossindex.htm Knots: http://members.aol.com/idfrank/knots.html

http://www.troop9.org/?s=knots/index http://www.realknots.com/knots/

UQ Injury, Illness & Incident Report form: http://www.uq.edu.au/ohs/pdf/accida.pdf UQ Diving Safety Manual: http://www.uq.edu.au/ohs/Divingweb.pdf

scientific scuba diver course to as/nzs 2299.2:2002biophysics.sbg.ac.at/transcript/ssd.pdfscientific...

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