MY ORAL QUESTIONS WITH ANSWERS

SAFTEY

DRAW THE CROSS SEC OF YOUR SHIP

What is Tumble home, moulded depth and moulded breadth

TUMBLE HOME

- The side shell of the ship towards the upper deck region curves towards the centre line of the ship.

- No significant importance other than style.

FREE BOARDFREE BOARD MARKDECK LINE

DECK LINE Horizontal line mark amid ships on both the sides Its upper edge coinciding with the upper surface of freeboard deck and outer surface of

the ship side Distance b/w the water line to deck line is called free board

FREE BOARD

- The freeboard assigned is the distance measured vertically downwards amidships from the upper edge of the deck line to the upper edge of the related load line

WHY FREE BOARD IS REQUIRED ?

- Sufficient freeboard is required at all times to prevent the vessel being swamped and

overwhelmed

- To prevent green seas on deck

-   satisfy IMO damage stability regulations due to increased reserved buoyancy.

(increased freeboard means increased internal volume. And if that internal vol is water

tight then means increased reserve buoyance)

FREE BOARD MARK Every ship should have free board marking marked on the either side of the ship ‘s hull at

its centre Its placed at the maximum draft at which the ships stability has been determined

- The ship should not operate in any condition if the freeboard mark is submerged during calm whether when ship at rest and upright

-

- Another diag. example:-

-

WHY LESS FREE BOARD ON TANKERS

1. High deck integrity2. Deck openings are very small3. Less density of cargo compared to grain4. Increased longitudinal and transverse subdivisions5. Larger and better pumping arrangements compared to normal cargo ships – in the

condition of ingress of bilge water6. Permeability is only 5% in oil tankers where, its 60 – 65 % in dry cargo ships.

Hence there is higher ingress of water

RESERVE BUOYANCEReserve buoyancy - as per reeds (ref reeds pg 111)

- It’s a potential buoyance of the ship which depends upon the intact water tight volume above the water line of the ship

- If a weight is added or buoyance is lost due to bilging, the reserve buoyance gets converted to buoyance by increasing the draft

- If the loss of buoyance exceeds the reserve buoyance ship will sink  

why is it needed ?-  It s defined as the buoyancy a ship can call upon to meet d loses of buoyancy due to

damage of main hull.Its use in the general working of the ship is to provide a sufficiency of freeboard to make the vessel seaworthy.

STIFF SHIP / TENDER SHIP STIFF SHIP TENDER SHIP

- Large GM- Very stable- Less roll period- Uncomfortable ride

- Small GM- Easy rolling and smooth rolling- Comfortable ride

STABILITY BOOKLETS- Gives the master an idea on how the vessel would react on different conditions of loading

- Consist guidelines on stability calculations, loading etc

- Inclination exp that are carried out, the values are recorded in stability booklets

- Any changes in the COG and light ship disp are duly recorded / updated in STABILITY

BOOKLETS

DAMAGE BOOKLETS - Consists on cases of ship damage and gives an idea on ship’s survivability

WHATS GROSS TONNAGE AND NET TONNAGE ?REFER DJ EYRES (PG 339 – TONNAGE)

GROSS TONNAGE NET TONNAGE

Overall ship’s internal moulded volume of ships revenue yielding volume

all enclosed spaces from keel to funnel i.e vol of cargo holds

to be more simple ., NET tonnage = (vessel’s gross tonnage) –( accomodation, machinery spaces, navigational room etc etc)

- Tolls for transiting Suez and panama are based on Net tonnage

Unit less index Unit less index

Used to determine things such asManning regulationsRegistration feesPort feesSafety rules

Used toCalculate port duties

Net tonnage should not be < 30% of gross tonnageIe. NT = 0.3 x GT

WHAT IS COMPENSATED GROSS TONNAGE - Thus the gross tonnage was a measure of comparing the output of various ship building

countries- But the statistics went wrong coz a 65000 GT passenger ship needed much more man

power and time to be manufactured compared to a 1,50,000 GT oil tanker. - So this lead to wrong interpretations- Hence CGT was introduced by association of west European ship builders and ship

builder’s association of japan - The CGT coefficient table consists of various factors , to find a CGT of a ship, the

relevant co efficient s has to be multiplied with (pg 343 DJ Eyers)

ANGLE OF LOLL – REGARDING – LOTS OF CROSS QUESTIONS AS WELL ANGLE OF LOLL AND HOW WILL YOU CORRECT IT:

ANGLE OF LOLL

- An initially unstable ship heels to a certain angle and ends up in neutral stability. That angle is called angle of lol

- At angle of loll ., GM = 0 OR KG = KM

CORRECTIVE ACTION

- First check if the vessel is listed or lolled- Always presume it is lolled for safety and work accordingly- Calculate the vol of all tanks check for any slack tanks if any for the reason listed - If the port and starboard listing moments are same then confirm its lolled- In a listed condition always try to lower the centre of gravity by

- discharging the high side of the ballast first

- start filling low side of the tanks (prefer smaller tanks to minimise free surface effect during filling )(coz if you fill the other side of the tank, the listing moment will be enough to capsize)

- gradually start filling the mid tank and then the port side tank

-- now the vessel should be upright , even if it is not ., try ballasting other tanks in the same

method

WHERE DOES ANGLE OF LOLL OCCUR

Occurs in timber carriers., - timber s on the deck absorb moisture and increases the cog Moreover, while sailing, consumption of fuel and water from the lower tanks also

increases the cog.

NOTE :- DURING LOLL – NEVER BALLAST THE HIGH SIDE OF THE TANK , BECOZ , THE SHIPS LISTING MOMENT TO THE OTHER SIDE IS ENOUGH FOR IT TO CAPSIZE

STATIC STABILITY (HE JUST ASKED ME THE REGULATION REGARDING THIS, JUST FOR YOU GUYS TO LEARN MORE ABOUT IT , I’VE ADDED EXTRA INFO, JUST GO THRO IT )STATIC STABILITY

DEFN

- Measure of ships tendency to retain its upright position if inclined by an external force

STATIC STABILITY REQUIREMENTS

- The initial metacentric height GM should not be less than 0.15 m- GZ should not be less than 0.2 m at heel = 30’- Max righting lever should occur at angle of heel > 30’ (in any ways not less than 25’)-- The area under the GZ curve should be

0.055 m rad upto heel = 30’0.09 m rad upto heel = 40’0.03 m rad between 30’<heel<40’ or 30’<heel< Angle of downflooding

(angle of downflooding means = angle at which deck immersion takes place )

CURVES OF STATIC STABILITY

- This curve is plotted for every voyage - And its for a particular KG and displacement

FROM THIS CURVE YOU CAN FIND

- INITIAL GM - A tangent drawn to the curve at initial point whr it meets at 1 rad ( that h = Initial Metacentric height)

- ANGLE OF CRONTRAFLEXURE - The angle till which the rate of GZ increases with increase in heel. Though after this GZ may increase, the rate of increase is slower

- ANGLE AT WHICH MAX GZ occurs - ANGLE OF VANISHING STABILITY

Beyond which the vessel will capsize- RIGHTING MOMENT AT ANY ANGLE CAN BE FOUND

- GZ x Displacement - MOMENT OF DYNAMIC STABILITY AT ANY PARTICULAR ANGLE

= Disp X A Displacement – tons Area in – Meter Rad - Area under the curve eg/ What s the dynamic stability at angle 20’so, the – AREA UNDER THE CURVE IS SHADED TILL 20’

(DYNAMIC STABILITY: Its nothing but the work done in heeling the ship to a particular angle )

NOW WHAT S CROSS CURVES OF STABILITY

- The static stability curve is plotted with the help of CROSS CURVES OF STABILITY - i.e. To plot Static stability curve u required values of GZ at Various angles of heel - Cross curves are nothing but curves plotted using

- GZ - ANGLE OF HEEL For VARIOUS DISPLACEMENTS

Now, since the curves cross each other, its called cross curves of stability

SHEER

- It’s the longitudinal curvature of the deck from fore to aft- Rising from midship to fore and aft- Makes the vessel sea worthy by raising the deck and preventing green seas on the deck

SHEER STRAKE

- Strake means hull/plating- Sheer strake means , a long continuous plate running on top of the main deck

STRAKE (Kemp and Young pg 48)

- Shell plating extending from fwd to aft - Named alphabetically starting from the strake adjacent to keel ( c,b,a – keel – a, b, c)- And its numbered from aft. i.e., Port C 12 would mean ,

C STRAKE – PORT SIDE 12 – From the aft start counting from 1 , 2, … until 12 th strake

Thickness

- The thickness of the strake is the max at the mid ship (0.4L)- And at the ends its (0.075L)- Thickness of the plating near Hawse pipe, stern frame , propeller should be 50% thicker

than the adjacent strake

HE ASKED ME ONLY ABOUT BAR KEEL (I’M GIVING YOU ALL TYPES OF KEELS AND FUNCTION S FOR YOUR REF)

THREE TYPES

- FLAT KEEL- BAR KEEL- DUCT KEEL

FLAT KEEL

- Used in all types of sea going vessels - Flat keel would basically mean a single bottom - In the olden days, above the floors, a wooden plank was placed to facilitate cargo

carriage. (now u might wonder that makes it a sort of double bottom right ? – ans is , its not, coz if it’s a double bottom, it should be water tight

BAR KEEL(ref DJ Eyers)

- A bar is placed in the centre of the keel called bar keel- The either side of the hull attached to the bar keel is called Garboard strake- These types of keels are incorporated in ferries or boats that are vulnerable to grounding

-

DUCT KEEL

- Also called as BOX KEEL, allows pipes and other services throughout the keel length.- This is fitted from the fwd of the e/r bulkhead to the aft of the collision bh- This keel facilitates pipe passing through the cargo holds and thus isolating piping from

cargo contact- This enables lines to pass through that facilitate draining

HOW IS BILGE KEEL ATTACHED ?

 Bilge keels, particularly on steel vessels, are "lightly welded" along a portion of the vessels length. This allows the bilge keel to be deformed or detached in case of impact without risking the vessels hull. Typically, short sections will be welded, with gaps between. The bilge keel will be attached to a backing strip - a strip of metal, which prevents the bilge keel from propagating cracks into the hull when damaged.

it reduces rolling basicly..it runs half length fwda nd half astern frm the mid ship

HE ASKED ME IF FLAT KEEL AND BILGE KEEL ARE SAME ?

(I KNOW THIS SOUNDS SILLY, BUT HE WANTED TO TEST ME IF I WAS SO DUMB ;) )

BILGE KEEL (pg 182 DJ Eyers)

- Used to dampen rolling- Increases the longitudinal strength along the bilges - Protects the bilges from grounding

Construction

- Its placed exactly by 90’ to the bilges - Supported by a backing plate or a ground plate- On the ground plate is whr the bilge keel is welded- Thickness of ground plate is equal to keel plate or can be 14 mm whichever is smaller - Extends aft more than it extends fwd- Should not extend more than the breadth and depth of the ship – or would be damaged

during docking

How ‘s it welded

- The ground plate is welded on to the shell by continuous fillet welds- The keel plate is welded on to the ground plate by light or intermittent welds as to ,

should the bilge plate get damaged due to grounding or so, it shouldn’t affect or have an impact on the shell , but if welded light with a ground plate behind backing it, the keel would get damaged without causing damage to the hull !

I WAS ONLY ASKED TO DRAW FLOOR OF MY SHIP I’M PASTING ALL TYPES OF FLOORS FOR YOU GUYS TO PRACTISE, WHICH EVER U GUYS FIND EASIER , SAY UR SHIP HAD THAT FLOOR !!

FLOORS

- These are transverse members that are perpendicular to the keel and girders - Increases the transverse strength along the ship

There are three types of floors

- 1. Solid floors- 2. Plate floors- 3. Bracket floors

Plate floor

Solid floor – used for stiffening whr floors are placed at every frame (under m/e, engine room, stern, fwd , bulbous bow etc)

-

Bracket or open floor

-

LIGHTENING HOLE

- A hole cut in a non – water tight structural member- For, weight reduction, accessibility and ventilation

WHAT IS TRANSOM FLOOR

TRANSOM FLOOR- Rudder post is carried into the main hull via the transom floor - The floor to which the rudder post is fitted is heavier with more substantial stiffening

arrangements , this floor is referred to as transom floor

THEN I WAS ASKED TO DRAW MY SHIP DB TANKS CROSS SECTION AND SOME CROSS QUESTION S AS IN , SHOW ME THE STIFFNERS , USE OF HOPPER TANK, DB TANK ETC

There are three tanks

- TOP SIDE TANK- HOPPER TANK- DB TANK

TOP SIDE TANK

- Used mainly for ballasting. Connected with the ships main ballasting system- Has triangular frames , the top portion supports deck beams,

the side portion supports the side plating of hullthe bottom portion supports the top side of the cargo hold

- As per BHU ( regulation regarding safe loading and unloading for bulk carriers) states that during discharge of top side tk, the amount discharged should be matched with the amount of cargo loaded

HOPPER TANK

- Enable s easy removal of cargo – by placing cargo in the centre for easy dispatch- Also used as extra ballast tanks- If in the aft, can be used for f.o tanks along with DB tanks

DB TANKS

- These tanks extend b/w fwd collision bh to aft peak bh - The DB tanks are constructed

if L > 120 – then these tanks are longitudinally framed (ie , floor spacing – 3.8 m apart- except pounding region, under m/e , boiler)if L < 120 – then these tanks are transversely framed (ie floor spacing – 3 m apart – except pounding region , under m/e , boiler)

WHAT IS HAWSE PIPE AND SPURLING PIPE - I JUST SAID TWO LINES ABOUT IT , HE WAS SATISFIED - FOR YOUR UNDERSTANDING , I’VE PASTED IT DOWN

HAWSE PIPE

- Strengthened – reinforced pipe which leads the chain ovbd is called a hawser - This is a tube

SPURLING PIPE

- Strengthened pipe, that leads the chain into the chain locker is called a spurling pipe- This is to prevent chafing – i.e. the tubular sct

HE ASKED ME IF MY SHIP WAS LONGITUDINALLY FRAMED / TRANS FRAMED (REMEMBER – ANY SHIP MORE THAN 120 m are longitudinally framed !! )

- Here you go with the details

TRANSVERSE FRAMING LONGITUDINAL FRAMING- For ship below 120 m - Compulsory for very long ships like oil

tankers and bulk carriersFLOORS – 3 m max 3.8 m

Solid floors at every frame space at – under m/e , boiler , pounding area , cargo spaces where grabs are used

INTERCOASTAL GIRDERS

If 10<B<20 mOne on either side

If B>20 mTwo on either sides

If 14<B<21One on either side

If >21 mTwo on either sides

Floors , frames , beams form rings and run throughout the ship giving transverse

strengthIt fails In long structures becoz, shear stress

is more

That’s why longitudinal framing is preferred over long ships

Frames are used Web frames are used not closely spaced as frames in trans framing

COLLISION BH REGULATION

SUMMARY

- From fwd perpendicular - 5%L or 10 m – MIN- 8%L or 5%L + 3m

- If bulbous bow is ther o From mid sec of bulbous bowo 3m from fwd perpendicularo 1.5% L from fwd perpendicular

- No manhole doors, no ventilation, if requ, 1 or 2 holes for ballasting / de ballasting fpt. (2 holes if 2 types of liquids are handled)

- If super sct is in fwd, then col bh should have an extension- Extension is not directly on top - 5% L from collision bh- Ramp and bow door are fitted whre ramp not > 2.4 m height. If > 2.4 m height then it s

not considered as an extention

Then , he asked me , what does solas chap 12 deal with I said – It deals with extra safety requirements for bulk carriers !

He said me to explain it !I was wondering how and whr to start !But I knew the cargo hold water ingress detection system well, so I started to talk about it trying to use as many words possible to elongate the topic !He looked me for sometime wondering what cross questions to ask !So I continued with lot of numerical values like the alarm should get activated when it reaches 0.5 m from the inner bottom and 15% of the vol of tk not more than 2 m etc etc !

- Guys !., talk confident about the numericals ,he ‘ll be impressed ! – well I guess he was in my case , coz I wasn’t asked any cross questions in this !!!!

- He simply put a tick mark and moved on to other question

For your knowledge , I’ve pasted here my version of solas chap 12 ! Just read fully u’ll know if this chap is asked , what to talk about !

SOLAS XII – ADDITIONAL SAFTEY MEASURES FOR BULK CARRIERS

SUMMARISED EDITION

- Damage stability requirements - Structural dimensions- Surveys - Booklet – info on compliance with this regulation regarding- Solid cargoes density declaration - Loading instrument - Hold , ballast space dry space, water ingress alarms - Pumping systems – remote operation- Restrictions for sailing with hold empty

DAMAGE STABILITY REQUIREMENTS

If the bulk carrier is of

- L > 150 m - Single skin and double skin (provided the inner long plating is < B/15 or 11.5 m from the

outer shell)- Carriers cargo > 1000 kg/m3- If its loaded to summer load line -- THEN SHOULD BE CAPABLE OF WITHSTANDING FLOODING OF ONE FULL

CARGO HOLD

NOW , L >150

- Cargo density > 1.7 kg/m3- A- THEN SHOULD BE ABLE TO WITHSTAND FORE MOST CARGO HOLD FLOODING

HERE , FLOODED WOULD MEAN

- Flooded till the outside water line - Permeability of loaded cargo hold is assumed – 0.9 - And permeability of empty cargo hold is assumed – 0.95

STRUCTURAL DIMENSION

- If the cargo hold is double skinned – then the stiffening members outside the hold So that the members don’t restrict cargo

- the distance b/w the outer plating and inner plating should not be less than 1000 m - Should be enough for people to pass through and conduct survey

- Cargo shouldn’t be carried in those spaces

- if ladders are present in the side spaces , the min free space should not be less than 600 mm

- If any single sct member fails, the whole sct should nt be jeopardised - Should facilitate normal loading of cargo – i.e. should have adequate strength if the cargo

of a specific density is dropped via a conveyor belt onto the holds

SURVEYS

- Bulk carriers of L > 150 m - Which is more than 10 yrs old - Cannot carry bulk cargoes of density > 1.7 kg/m3 unless they are permitted to do so by

the admin

PERIODICAL SURVEYS

- Conducted in accordance with ENHACED SURVEY PROGRAM , - Inspection carried out on all cargo hold, hatches , hatch covers – and they are

ensured safe

LODICATOR SOFTWARE

- The bulk carriers L > 150 m shall be equipped with a software that helps in calculation of shear stress, bending moments

BOOKLET

- It should also be presented with a booklet that would clearly state that the bulk carrier has successfully complied with the regulation 4,5,6,7 of this annex

- This booklet is endorsed by admin

Which are namely - DAMAGE STABILITY- Sct requirements - Surveys

SOLID CARGOES DENSITY – DECLARATION

- Prior to loading, the shipper shall declare the density of the cargo along with cargo information

- Any cargoes with density between 1.2 to 1.7 shall have its density verified by an accredited organisation

HOLD S BALLAST SPACE WATER INGRESS ALARMS

- all bulk carriers should be fitted with water ingress alarms at every cargo hold – audio and visual (at CCR, BRIDGE , ECR)

- Remember – visual alarm to clearly indicate the different level of liquid

Working

- 0.5 m (from the inner plating of the hold ) – audible and visual alarm - 15% of tk capacity not more 2 m – audio and visual alarm

- The alarm should be fitted in the aft of cargo holds

- Overriding arrangement also should be provided (if the tanks are ballasted)

- in fwd of coll bh – alarm at 10% of tank capacity- except chain locker , any other room fwd of collision bh – 0.1 m above the deck water

ingresses – alarm

PUMPING SYSTEMS

- Any holds, ballast fwd of collision bh should have appropriate pumping arrangements - This should be facilitated with activation of pumping systems from BRIDGE, ECR, CCR - Ensure, personnel presence locally is not required (i.e. he hasn’t go to the free board

deck to start the operation)-- Opening and closing of valves – REMOTE operation is accepted

RESTRICTION FROM SAILING WITH ANY HOLD EMPTY – If cannot meet flooding requirements

- L> 150m - Single skin- Density > 1.7

If cannot meet the requirements of single cargo hold flooding

These ships then, cannot sail with a single cargo hold loaded < 10% of the max cargo capacity of that hold – after loading to summer load line

FOR THOSE SHIPS WHICH CANNOT COMPLY TO THE REQUREMENTS

- Frequent surveys carried out on cargo hold and sct regarding its maintenance- Water ingress alarms in all holds- Possible flooding scenarios and guidelines of evacuation plan for crew members

USE OF ISOLATION VALVE ?- If any part of line ruptures we can isolate it by shutting the isolating valve for that section

thus maintaining the fire line integrity

- (he expects only this line ! )

ENCLOSED SPACE ENTRY PROCEDURES

ENCLOSED SPACE ENTRY

- Risk assessment by 2E /Co- Meeting discussing the possible hazards - Also worst case scenarios are presumed and actions to be taken are discussed- The work done to be well instructed to people who r going to do the work

- CHECK LIST IS FILLED by 2E / CO and permit requested for a certain period of time

- WORK PERMIT TO BE SIGNED BY MASTER

- Ensure tank / be it anything, is not pressurised- Pump out all the liquids – if applicable- Once no pressure inside the tank- Ventilate it thoroughly - Adequately check for o2 content , if its less than 21% never get into - Continue ventilation - Now, after oxygen content in the tank is 21%- Make sure a stby person is outside with communication means, extinguisher, all first aid

kits including Stretcher - With BOARD saying “MEN AT WORK”- Resuscitation and rescue equipments kept ready along with stretcher

- After all the work is finished, ensure “AFTER WORK CHECK LIST” Should be filled - The WORK PERMIT is closed

My cross question s in this

- If your o2 analyser had a hole in it and is showing you the wrong reading , - As a fourth engineer how will you find out ?

( I didn’t know the ans for this )- How will check the span ?? – use pentane gas - What should be the level of HC content in enclosed space for a man to enter ? – ii don’t

know this too ! –sorry !

HAZARDOUS AREA

- Potential flammable or explosive atmosphere

Eg.

Cargo tanks, Fuel oil tanks

Enclosed spaces

Coffer dam which is rusted

Sewage tanks (presence of H2S and methane due to anaerobic bacteria)

That ‘s it about safety !

NOW, 4B

Tie rods – he mainly wants, if you open cc door , will you be able to see tie rods ??

TIE RODS - Prevents distortion of main bearing - (this is what surveyor expects !!)- Helps keep the engine sct under compression - Prevents fretting of gears

They are positioned at each transverse girder - Keeps the trans girder under compression thus preventing fatigue cracking

They are supported by pinching screws, which help in dampening the vibration on the tie rods, thus improving the fatigue life

- Tensioning of tie rods are done by hydraulic tightening - Done from Centre of the engine, alternatively fore and aft

Note: Tie rods are not required on medium speed engines becoz of their fairly think sections used

- If thick sections are used, then stress is lower

The SMC-C is the advanced type, which has twin stay bolts

“THE BEST IN REDUCING DISTORTION OF MAIN BEARING”

SMC – C ENGINE SMC ENGINE

SAFTEY VALVE DRAWING – U KNOW

CENTRIFUGAL PUMP DWG - U KNOW

WHAT IS FIRE RING OR ANTIPOLISHING RING?

PISTON CLEANING RING/ANTI POLISHING RING/FIRE RING

- Fitted on top edge of the liner, smaller than the liner dia , slightly larger than the piston crown

- Purpose is to remove carboneous deposits at top land portion of piston (Top land portion : means, area b/w top of piston ring and piston crown)

- In the absence of this ring, liner surface will be polished by the abrasive particles

COMPRESSOR PV DIAGRAM - U KNOW

INDICATOR CARDS

INDICATOR CARDS(refer AJ Wharton pg: 21)

- These are nothing but pressure and volume graphs - Which gives a detailed info on what happens inside the engine

There are 4 types of indicator cards- Power card- Compression diagram- Draw card- Light spring diagram

Power card- Its taken in phase with the piston movement

Compression diagram- This is also same as power card (i.e. its in phase)- The only difference in this is that, the fuel supply is cut off - Thus this gives Max compression pressure

Note: A decrease in height of this curve would indicate, broken exhaust valve, blow by, worn liner etc

Draw card- This is 90’ out of phase - This indicates more clearly the pressure changes - But the p com is super imposed

LIGHT SPRING DIAGRAM- This is again similar to power card (i.e. in phase with the piston movement)- The only difference is that, the card is taken with a light spring- The use being, exhaust and scavenge pressure changes are shown enhanced

Ref pg 24-27 for fault finding

NOW, if its 2s engine Draw card can be taken / a power card can be taken If it’s a 4 stroke, this becomes impossible because of the high speeds

- Hence instead of calculating MIP (mean indicated pressure) and then calculating the power, in 4s ignition jump is calculated

- Ignition jump = peak pr – compression pr - Peak pressure is calculated from “PEAK PR INDICATOR”- And fuel supply is cut off, now, calculate the peak pr – that’s P com - Thus IGNITION JUMP can be calculated by subtracting the two. - Using ignition jump the power of engine is calculated

ALMOST EVERYTHING REG VIT WORKING ON SULZER TYPE AND B&W – I WAS ASKED !

SO , I’M PASTING ALL THE MAT REG IT ! – STUDY WELL !

VIT – VARIABLE INJECTION TIMING

- As the load increases in the engine, Pmax also increases. But at low loads Pmax is low. - With the help of VIT, Pmax is attained at low loads, leading to low sfoc- Increased thermal efficiency

no smoky exhaustimproved temp control to prevent corrosionstrength of crank shaft is utilised better

WHY REQUIRE VIT- It enables to make small changes in fuel pump timing during

1. Wear on fuel pump cam2. Allow Pmax balancing of individual cylinders 3. Fuels of poor ignition qualities - compensation4. Changes in cam shaft timing due to chain elongation

- Enables a change in timing of 2 deg

WORKING:-- The spill and suction ports are raised up and down- Up – delayed injection- Down – advance injection

During low loads upto 40%MCR, fuel injection is constant (REF THE BELOW DWG)

(This is done to prevent frequent changes of pump lead during manovering ) The injection advances till 85% of MCR- now engine would’ve reached its Pmax The piston servos would start retarding to maintain the Pmax till 100% MCR

At low loads (TILL POINT 1 IN THE GRAPH)- Vit not in operation till 40% MCR- Control air pr = 0- Injection = delayed

At Increasing loads - After pt 1 , fuel starts advancing- Control air pr = 0.5 bar- Injection = advancing

During 1 to 2 - Fuel injection = Advances till it attains 85% MCR.- Once this is attained , then starts retarding to maintain Pmax- At 85% load , position sensor – fully depressed- Should be touching both the pivot points

After 2 - Fuel injection = Retards to maintain Pmax

Refer devan aranha for diagrams

SUPER VIT:- It’s a jerk type pump consisting of- Double threaded barrel- Piston servo unit (input from governor)- VIT regulating lever- Control air signal- Position sensor- Fqs lever

Super vit is used on larger – L,K,S , MC ENGINESL- LONG STROKE, K – SHORT STROKE, S – SUPER LONG STROKM- PROGRAMMEC- CAM SHAFT CONTROLLED

SUPER VIT = ADJSTABLE TIMING AND ADJUSTABLE BREAK POINTCONVENTIONAL VIT = ADJUSTABLE TIMINGS BUT FIXED BREAK POINT

ADJUSTMENTS - (for this refer the upper pic)1. INDIVIDUAL ADJUSMENT2. COLLECTIVE ADJUSTMENT

1.INDIVIDUAL ADJUSMENT- Done to individual pumps to adjust the Pmax - by moving piston servo or the thread between the vit rack and piston servo

COLLECTIVE ADJUSTMENTS- Done to all the units collectively (cause fuel quality, cam shaft timing change becoz of

chain elongation)- done using adjusting screw s on the position sensor – which alters control air pr to

advance or retard the vit

THE NON RETURN THROTTLE VALVE – USES- This valve is present between piston servo and position sensor- Prevent excessive Pmax during sudden reduction of load when operating above the

break point ( rough weather)- Ensures stable VIT rack , prevents rapid fuel rack oscillations

VERY IMP – BREAK POINT VALUES FIXED PITCH PROPELLER –MK I ENGINES - 78% LOAD

MK II ENGINES – 80 % LOADCONTROLLED PITCH PROPELLER - 85% LOAD

FUEL PUMP - There are two types of fuel pump

1. MAN B&W (JERK TYPE)2. SULZER

SULZER FUEL PUMP 1. CAM IN THE BASE CIRCLE: Suction valve open2. During plunger’s upstroke: suction valve is closed

Thus starting injection 3. At the end of injection: Spill valve is opened

VARIATION OF SUCTION – GIVES THE PUMP VIT VARIATION OF SPILL – ENABLES THE PUMP TO CONTROL THE QUANTITY OF FUEL

THEREFORE SUCTION VALVE – VIT, FUEL QUAITY SETTING(MANUAL)SPILL VALVE – FUEL RACK (i.e. fuel quantity)

HOW TIMING IS ADJUSTED?

- Governor controls the fuel quality settings, - This fuel quality setting controls the fuel quality control shaft- This control shaft, controls the adjustable pivot in the suction valve - Thus changing the timing

Spill valve pivot is also controlled by governor output NOTE NORMAL ADJUSTEMNT

- The VIT is adjusted in such a way that, the advancement is only above 40% of load until Pmax is attained at 85% of load

- Then the timing retards as to maintain the Pmax until 100% MCR

Now, why the VIT is adjusted in such a way that It advances at 40% of the load ? why not start early and reach Pmax before 85% ?

- Reason being, to avoid excessive pump lead during manoeuvring

There is also a FQS lever which can be set manually to retard or advance the fuel pump timing (i.e. suction valve)

- This is manually done to alter/ compensate different fuel qualities

FUEL PUMP SAFTIES- Erosion plug- Umbrella seal- Puncture valve - Shock absorbers

LOST MOTION

FUEL PUMP CAM – has to be retimed when the engine changes its direction (ref marine diesel uk – lost motion for detailed info)

So there are three ways of changing the cam timing- TURN THE CAM (SULZER)- MOVE THE FOLLOWER (MAN B&W)- MOVE THE CAM SHAFT AXIALLY FOR A DIFFERENT SET OF CAMS

IN TURNING THE CAM, ITS ROTATED BY – HYDRAULIC OPERATED SERVO MOTOR

- Thus by turning the cams the cams are timed according to the crank shaft

- The angle through which the cams are turned is called “LOST MOTION ANGLE”

HE ASKED ABOUT THRUST BEARINGS !

THRUST BEARING Discovered by George Mitchell in 1905 (Australian engineer) , at the same time, An American Albert Kingsbury also invented a bearing with the same principle

USES- Used to save crank shaft from axial propeller thrust - Used to transmit propeller thrust to the ships hull

Working- A tilted pad skims over a sheet of oil surface- The wedge / the pad is tilted to enable generous lub oil flow towards it - Has two parts

1. Collar 2. Thrust pads

- MARINE DIESEL ENGINES -> collar – rotating/ Thrust pads – stationary- And also can be viceversa

IN MARINE DIESEL ENGINES- Thrust block consists of a housing which consists of number of wedge shaped tilting

pads backed up by a steel support- The housing is bolted to the ship’s hull via holding down bolts

In smaller thrust bearings, the wedges are machined into the bearing Eg. T/C thrust bearing - MAN B&W (Pic 2)

Now how ‘s it lubrication carried out?(ref devan aranha pg 149)

- The oil is supplied from the pressure lubrication system of engine

- The lub oil or cooling oil is sprayed directly on the fwd and aft of thrust collar by means of nozzles

- These nozzles are positioned in between the pads

THIS IS VERY IMP !

THIS HELPED ME INFACT TO MAKE HIM SMILE WHEN I ANSWERED THE DIFFERENCES IN THIS ORDER

DIFFERENCE BETWEEN MANB&W AND SULZER

MAN B&W SULZER

REVERSING- Gain motion

i.e. the cam shaft turns in the same direction when the engine is reversed

- The followers shift positions

- Lost motion

i.e. the cam shaft is rotated by a hydraulic servo motor to a required position during reversing

CROSS HEAD LUBRICATION

- Utilises system pressure 2.5 to 3 bar- Has patent on the increased dia on the

cross head pin and enhanced super finish polished surface

- Wedged oil grooves to further add to the cooling and lubrication of bearings

- Telescopic arm

- Has a separate cross head pump for lubrication

- Has a patent on forced lubrication- 12- 15 bar pr is used- Compared to B&W, pin dia is smaller

with lesser surface finish

- Articulated arm

FUEL PUMP

- JERK TYPE- Has suction and spill ports- Plunger has a helix

- Has suction and spill valves- Plunger doesn’t have helix

CYLINDER HEAD RELIEF VALVE

- Elastic studs

- Relief valve

CYLINDER LUBRICATION- Alpha lubricator

- Load controlled electric motor

PISTON RING NO’S - 5

- 4

MOMENT COMPENSATORSCHAIN

- GEARS

TIE ROD TIGHTENINGFWD TO AFT

- START FROM THE CENTRE- ALTERNATE B/W FORE AND AFT

THE LAST QUESTION

HE ASKED ME REG REVERSING !

REVERSING(Devan aranha pg 190)

RD AND RND ENGINES- Here the whole of cam shaft is moved (NOT THE CAMS ALONE) - During reversing, the cam shaft is fully-including all the cams, ie. Fuel, air, exhaust valve

cam - turned at an angle of 90’- Further, the exhaust cam is turned at an angle of 160’ in the opposite direction - The cam shaft is turned with the help of hydraulic servo motor- The reason in these engines even the exhaust cam is turned is,

- the exhaust valve is of rotary type - And its not symmetric to BDC

- IN RD AND RND , EXHAUST CAMS REPOSITIONING REQURIED

RTA ENGINES - Here the CAM ‘S OF THE FUEL PUMP and starting air is turned. –NOT HE WHOLE

CAM SHAFT. This is called lost motion !- Coz exhaust cam here is symmetric to BDC and it doesn’t require repositioning- Hence, the hydraulic servo motor turns the fuel cams to 70 in the opposite direction - And start air cam s to 98’ in the opposite direction

- Now, one hydraulic servo motor can reposition 2 fuel cams

4S – ENGINES - CRANK SHAFT IS AXIALLY SHIFTED WITH A WHOLE SPARE SET OF CAMS TO BE

OPERATED IN THE REVERSE DIRECTION

MC ENGINES (B&W engines)- Here instead of shifting the cam shaft or cam s, the roller of the fuel pump is shifted - This is called Gain motion. - For fuel pump

- Rollers are shifted - By individual pneumatic cylinders - once its shifted, the rollers are self lockable - After shifting, the pneumatic cylinder is de pressurised and vented- Each and every unit has its own pneumatic cylinder

- Air cam’s - i.e. the rotary disc is turned by Reversing pneumatic cylinder

I SAID ALL THIS !

AND WHEN WANKEDE SAW MY MARKS ! – HE SAID TO ME

MR. RAJARAM, YOU DON’T DESERVE TO BE ASKED THE DECIDING QUESTION !

WISH YOU GOOD LUCK SAILING !!

GOD !! I’VE BEEN WAITING FOR THESE MOMENTS !

GUYS ! –EVERY ONE !! – DO REALLY WELL !

WORK HARD ! – ITS ONLY FOR A COUPLE MORE MONTHS !, THEN YOUR 2,00,000 RS SALARY IS AT YOUR DOOR STEP !!

CHEERS

HOPE YOU FOUND THIS USEFUL

ALL THE VERY BEST !!

GOKUL