ship handling & manovering course_part b.pdf

8/18/2019 Ship Handling & Manovering course_Part B.pdf

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Ship Handling and Maneuvering Course ISC

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CHAPTER ONE

Review of Basic Principles

Basic principles To Be Observed In Keeping A Navigational Watch

a.

Parties shall direct the attention of ship owners, ship operators,masters and watch keeping personnel to the following principles

which shall be observed to ensure that a safe navigational watch is

maintained at all times.

b. The master of every ship is bound to ensure that watch keeping

arrangements are adequate for maintaining a safe navigational watch.

Under the master's general direction, the officers of the watch are

responsible for navigating the ship safely during their periods of duty

when they will be particularly concerned with avoiding collision and

stranding.

c. The basic principles, including but not limited to the following, shall

be taken into account on all ships.

d. Watch arrangements

i. The composition of the watch shall at all times be adequate and

appropriate to the prevailing circumstances and conditions and shall

take into account the need for maintaining a proper lookout.

ii.

When deciding the composition of the watch on the bridge, which may

include appropriate deck ratings, the following factors, shall be taken

into account:

· At no time shall the bridge be left unattended;

· Weather condition, visibility and whether there is daylight or

darkness;

· Proximity of navigational hazards which may make it necessary for

the officer in charge of the watch to carry out additional

navigational duties;

·

Use and operational condition of navigational aids such as radar orelectronic position indicating devices and any other equipment

affecting the safe navigation of the ship;

· Whether the ship is fitted with automatic steering;

· Any unusual demands on the navigational watch that may arise as a

result of special operational circumstances.

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e. Navigational duties and r esponsibilities

i. The officer in charge of the watch shall:

¨ Keep his watch on the bridge which he shall in no circumstances

leave until properly relieved.

¨ Continue to be responsible for the safe navigation of the ship,

despite the presence of the master on the bridge, until the master

informs him specifically that he has assumed that responsibility and

this is mutually understood.

¨ Notify the master when in any doubt as to what action to take in

the interest of safety.

¨ Not hand over the watch to the relieving officer if he has reason

to believe that the latter is obviously not capable of carrying out hisduties effectively, in which case he shall notify the master

accordingly.

ii.

On taking over the watch the relieving officer shall satisfy

himself as to the ship's estimated or true position and confirm its

intended track, course and speed and shall note any dangers to

navigation expected to be encountered during his watch.

iii.

iv.

A proper record shall be kept of the movements and activities

during the watch relating to the navigation of the ship.

f.

Look-out

In addition to maintaining a proper look-out for the purpose of fully

appraising the situation and the risk of collision, stranding and other

dangers to navigation, the duties of the look-out shall include the

detection of ships or aircraft in distress, shipwrecked persons, wrecks and

debris. In maintaining a look-out the following shall be observed:

i.

The look-out must be able to give full attention to the keeping of a proper look-out and no other duties shall be undertaken or assigned

which could interfere with that task;

ii.

The duties of the look-out and helmsman are separate and the

helmsman shall not be considered to be the look-out while steering,

except in small ships where an unobstructed all-round view is

provided at the steering position and there is no impairment of night

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vision or other impediment to the keeping of a proper look-out. The

officer in charge of the watch may be the sole lookout in daylight

provided that on each such occasion:

¨ The situation has been carefully assessed and it has been

established without doubt that it is safe to do so ;¨ Full account has been taken of all relevant factors including, but

not limited to:

· State of weather

· Visibility

· Traffic density

· Proximity of danger to navigation

· The attention necessary when navigating in or near traffic

separation schemes.

iii.

Assistance is immediately available to be summoned to the bridge

when any change in the situation so requires.

g.

Fitness for duty

The watch system shall be such that the efficiency of watchkeeping

officers and watchkeeping ratings is not impaired by fatigue. Duties shall

be so organized that the first watch at the commencement of a voyage and

the subsequent relieving watches are sufficiently rested and otherwise fit

for duty.

h. Navigation

i.

The intended voyage shall be planned in advance taking into

consideration all pertinent information and any course laid down shall

be checked before the voyage commences.

ii.

During the watch the course steered, position and speed shall be

checked at sufficiently frequent intervals, using any available

navigational aids necessary, to ensure that the ship follows the plannedcourse.

iii.

The officer of the watch shall have full knowledge of the location and

operation of all safety and navigational equipment on board the ship and

shall be aware and take account of the operating limitations of such

equipment.



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iv.

The officer in charge of a navigational watch shall not be assigned or

undertake any duties which would interfere with the safe navigation of

the ship.

i.

Navigational equipment

i. The officer of the watch shall make the most effective use of all

navigational equipment at his disposal.

ii.

When using radar, the officer of the watch shall bear in mind the

necessity to comply at all times with the provisions on the use of radar

contained in the applicable regulations for preventing collisions at sea.

iii. In cases of need the officer of the watch shall not hesitate to use the

helm, engines and sound signaling apparatus.

j.

Navigation with pilot embarked

Despite the duties and obligations of a pilot, his presence on board does

not relieve the master or officer in charge of the watch from their duties

and obligations for the safety of the ship. The master and the pilot shall

exchange information regarding navigation procedures, local conditions

and the ship's characteristics. The master and officer of the watch shall

co-operate closely with the pilot and maintain an accurate check of the

ship's position and movement.

If any doubt as to the pilot

s actions or intentions, the officer in charge of

the navigational watch shall seek clarification from the pilot and if doubt

still exists, shall notify the master immediately and take whatever action

is necessary before the master arrives.

k. Protection of the marine environment

The master and officer in charge of the watch shall be aware of the

serious effects of operational or accidental pollution of the marineenvironment and shall take all possible precautions to prevent such

pollution, particularly within the framework of relevant international and

port regulations.



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The Properties Of Different Chart Projection Used For Navigation

For the purposes of navigation it is necessary to project the features of the

Earth's surface on to a chart. A projection is a means of representing a

spheroid surface on a plane. It is usually expressed as a mathematicalformula for converting geographical co-ordinates on the spheroid to plane

co-ordinates on the chart or map. Provided it is suitable a projection may

be used to represent any portion of the Earth's surface.

Since it is impossible to fit exactly a plane surface on to a spheroid one,

projections of anything but very small areas will contain some distortion,

see Fig. (1).

The distortion of a projection must involve some or all of the following

properties:

¨ Shape.

¨ Bearing.

¨ Scale.

¨ Area.

It is possible to devise a good projection, which will eliminate or reduce

to negligible proportions some of these distortions while keeping the

others within reasonable and thus usable limits. The choice of projection

for a chart or map is governed by the requirements of the user. Themariner requires a chart which will not only show the correct shape of

the land he is looking at, but also give him his correct position, course

and speed when he plots bearings and distances on it. Unfortunately all

these requirements cannot be met in one single projection, and a

compromise must be made by accepting a very close approximation to all

three (shape, bearing, distance), or satisfaction of two (usually shape and

bearing) at the expense of the third (distance or scale).

The network of lines representing the meridians of longitude and parallels

of latitude, which derive from any projection, is known as a graticule.A grid is a reference system of rectangular (Cartesian) co-ordinates

obtained when a projection is applied to a particular part, or the whole of

the world.

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Fig. (1) Projections Of A Sphere



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Mercator Projection / Chart

To the navigator, the most useful chart is one on which he can show

the track of his ship by drawing a straight line between his starting point

and his destination, and thus measure the steady course he must steer in

order to arrive there. Fig .2 shows mercator projection of north atanticocean The Mercator chart permits him to do this because it is constructed

so that:

¨ Rhumb lines on the Earth appear as straight lines on the chart.

¨ The angles between these Rhumb lines are unaltered, as between

Earth and chart.

It therefore follows that:

§

The equator, which is a Rhumb line as well as a great circle, appears onthe chart as a straight line.

§ The parallels of latitude appear as straight lines parallel to the equator.

§

The meridians appear as straight lines perpendicular to the equator.

The idea of the projection belongs to Gerhard Kremer, a Fleming who

adopted the name Mercator. Kremer used the graticule derived from the

projection in the world map, which he published in 1569.

The graticule, however, was inaccurately drawn above the parallels of

40°, and there was no mathematical explanation of it. That was not

forthcoming until Wright calculated the positions of the parallels and

published the results in his Errors of Navigation Corrected thirty years

later.

The chart came into general use among navigators in about 1630, but the

first complete description of it did not arrive until 1645, when Bond

published the logarithmic formula.

Gnomonic Projection/ Chart

In order to assist the navigator in finding the great-circle track

between two places, charts are constructed so that any straight line drawn

on them shall represent a great circle. These are known as gnomonic

charts, and they are formed by projecting the Earth's surface from the

Earth's center on to the tangent plane at any convenient point. They are



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Fig. (2) Mercator Projection Of The North Atlantic Ocean



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thus a zenithal projection. The Gnomonic projection is a perspective

projection, the meridians and parallels being projected on to the tangent

plane from the center of the sphere. The tangent point is chosen at the

center of the area to be shown on the chart, to minimize distortion, see

Fig.( 2)

Since a great circle is formed by the intersection of a plane through the

Earth's center with the Earth's surface, and as one plane will always cut

another in a straight line, all great circles will appear on the chart as

straight lines. However, the meridians will not be parallel unless the

tangent point is on the equator, nor will Rhumb lines be straight. Angles

are also distorted, except at the tangent point. It is therefore impossible to

take courses and distances from a Gnomonic chart.

Datum Used On Charts:

a. Plotting a position

A position may expressed by its latitude and longitude, or as a range and

bearing from a specific object. It may be plotted on the chart using a

parallel rule, dividers and the scale of latitude and longitude appropriate

to the chart itself but what about the reference datum.

Ø Reference datums and spheroids

Throughout the world, a number of these datums and associated spheroidshave been used for charting. In consequence, there are differences to

geodetic latitudes and longitudes, albeit small, between different charting

systems. Table gives some examples of the datums and spheroids used.

Ø Satellite geodesy

Since the 1960s the limitations of the classical methods have been

overcome by the use of extremely accurate satellite techniques. Accurate

co-ordinates of ground stations and the Earth's gravity field have been

determined, from Doppler and laser observations to satellites, and the

height of the geoid has been measured over sea areas by satellitealtimetry. By combining these data with surface measurements, a

worldwide 3-D reference system and a spheroid which best fits the geoid

have been defined. It has also been possible to establish the relationships

between previously unconnected datums and to convert them to the world

datum.



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Ø World geodetic systems (WGS)

In the past the differences in the various datums used for charting had

very little effect on the day to day navigation of ships, particularly as the

errors inherent in astronomical observation were larger than anydiscrepancy in charted latitude and longitude. However, it became clear

in the late 1950s that the increasing range of weapon systems (thousands

of miles in some cases) and the requirements for manned space flight

necessitated the establishment of an agreed worldwide spheroid which

fitted the actual shape of the whole Earth as closely as possible and whose

center coincided with its center of mass. This came about with the

development of the World Geodetic System 1972 (WGS 72) spheroid,

details of which are given in Table 1. A few metric charts throughout the

world are now compiled on this basis.

The US Navy Navigation Satellite System (TRANSIT), which came into being in 1964, is now based on WGS. The increasing world-wide use of

this system, accurate to the order of 100 meters, shows up the

siscepancies in the various datums used for charting.

It has thus become necessary to tabulate this discrepancy on any chart not

based on WGS in the form of a correction to the latitude of the position

obtained from TRANSIT. This correction is known as the datum shift and

may be as large as several hndred meters in well surveyed areas.

For example, in Southampton Water the datum shift amounts to about130 metrs (145 yards). A further error, amounting to a mile or more in

poorly surveyed areas such as parts of the pacific ocean, may also arise

from errors in the charted geographical position.

A similar problem exists with the Royal Navy's automated Navigational

Plotting System, which is also based on WGS.

NAVSTAR GPS is based on the WGS 84 Datum, which uses the GRS

(Geodetic Reference System) 80 Spheroid. As far as the navigator is

concerned, the differences between WGS 72 and WGS 84 are negligible.

b. Height

Height on Admiralty charts is given above a particular datum. This is

Mean Height Water springs in areas where the tides are semi-diurnal and

Mean Higher High Water where there is a diurnal in equality. Mean sea



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level is used in places where there is no tide.

In most instances, the position of the height is that of the dot alongside

the figure, thus: * 135. Heights, which are displaced from the feature

(e.g. a small islet) to which they, refer, or which qualify the description of

a feature (e.g. a chimney) are placed in parentheses.

Ø Drying heights .

Underlined figures on rocks and banks, which uncover see Fig.(3) give

the drying heights above chart datum in meters and decimeters or in feet,

as appropriate.

Ø Tidal stream information

1.

All information about tidal streams, whether in tables, or innotes giving the times of slack water and the rate of the tidal

streams, is given in some convenient place on the chart and

referred to by a special symbol [e.g. à] at the position for

which the information is given.

2. This information may be shown by means of tidal stream

arrows on certain charts when insufficient data for

constructing tables are available.



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Fig. (3) Tide Levels And Heights



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c. Depths

The unit in use for depths is stated in bold lettering below the title of the

chart. It is also shown, in magenta, outside the bottom right and top

left-hand corners of metric charts.

On all charts, the position of a sounding is the center of the space

occupied by the sounding figure(s). On metric charts, soundings are

generally shown in meters and decimeters in depths of less than 21

meters; elsewhere in whole meters only. Where navigation of

deep-draught vessels is a factor and where the survey data are sufficiently

precise, soundings between 21 and 31 meters may be expressed in meters

and half-meters.

On fathom charts, soundings are generally shown in fathoms and feet indepths of less than 11 fathoms and in fathoms elsewhere. In areas used by

deep-draught vessels where the depth data are sufficiently precise, charts

show depths between 11 and 15 fathoms in fathoms and feet. Some older

charts show fractional parts of fathoms in shallow areas and a few older

charts express all soundings in feet.

Depths on charts are given below chart datum. On metric charts for which

the UK Hydrographic Department is the charting authority, chart datum is

a level as close as possible to Lowest Astronomical Tide (LAT), the

lowest predictable tide under average meteorological conditions. Onearlier charts and those based on foreign charts, chart datums are low

water levels, which range from Mean Low Water to lowest possible low

water in tidal waters; in non-tidal waters, such as the Baltic, chart datum

is usually Mean Sea Level. A brief description of the level of chart datum

is given under the title of metric charts.

Large and medium scale charts contain a panel giving the heights above

chart datum of either Mean High and Low Water Springs and Neaps, or

Mean Higher and Lower High and Low Water, whichever is appropriate.

d. Direction

A line on the Earth's surface, which cuts all the meridians and parallels at

the same angle is called a Rhumb line. If two places on the Earth's surface

are joined by a Rhumb line and the ship steers along that line, the

direction of the ship's head will remain the same throughout the passage.

This direction is determined by the angle from the meridian to the Rhumb



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line, measured clockwise fr om 0° to 360°, and is called the course. The

Rhumb line itself is often spoken of as the course. On the Earth's surface,

a continuous Rhumb line will in general spiral towards the pole. To the

navigator, the most useful chart is one on which he can show the track of

his ship by drawing a straight line between his starting-point and his

destination, and then measure the steady course he must steer in order toarrive there. Table (1) shows the accuracy of position fixing method

Table (1)Methods Available For Position Fixing And Their Accuracy

Position Fixing Accuracy (95%)

D.G.P.S 5-10 meter

G.P.S 100 meter

Radar observation Depending on method used

Accuracy Of Range And Bearing Measurements Required By The

Performance Standards For Radar Equipment

1. Range Performance

The operational requirements under normal propagation conditions, when

the radar antenna is mounted at a height of 15 meter above sea level, is

that the equipment shall 'in absence of clutter give a clear indication of:

a) Coastlines

· At 20 nautical miles when the ground rises to 60 meters.

· At 7 nautical miles when the ground rises to 6 meters.

b) Surface objects

· At 7 nautical miles a ship of 5000 tons gross tonnage, whatever her

aspect.

· At 3 nautical miles a small vessel of 10 meters 'in length.

· At 2 nautical miles an object such as a navigational buoy having an

effective echoing are of approximately 10 square meters.

2. Minimum Range

The above-specified surface object shall be clearly displayed from a

minimum range of 50 meter up to range of one nautical miles, without

changing the setting of controls other than the range selector.



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The minimum range is the shortest distance at which, using the range

scale between 0.5 and 0.8 nautical miles, a target is still presented

separately from the trace origin.

3. Range Measurements

The equipment shall provide the following set of range scales of display:

1.5, 3, 6 , 12 and 24 nautical miles and one range scale of not less than

0.5 and not greater than 0.8 nautical miles. Additional range scale may be

provided, which are either smaller than the range scale between 0.5 and

0.8 nautical miles or greater than 24 nautical miles. Fixed electronic range

rings shall be provided for range measurements as follows:

· On the range scale between 0.5 and 0.8 nautical miles, at least two

range rings.

· On each of the other range scales six range rings.

· where off-setting facilities are included in the equipment additional

range rings shall be provided on each range scale so that the range

rings extend from the point of maximum offset to the edge of the

display farthest from that point . On each range scale the distance

between the additional range rings shall be the same as the distance

between the range rings provided in accordance with 1 and 2 above as

appropriate.

· A variable electronic range marker shall be provided with a numeric

readout of range.

· The maximum range of the variable range marker shall not exceed

significantly the maximum range of the longest radar scale.

· Fixed range ring s and variable range markets shall enable the range of

an object to be measured with an error not exceeding 1.5% of the

maximum range of the scale in use or 70 meters, which ever is greater.

· It shall be possible to vary the brilliance of the fixed range rings and

variable range markets and to remove them completely from the

display.



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4. Bearing Measurements

· Provisions shall be made to obtain quickly the bearing of any object

whose echo appears on the display.

·

Any means provided for obtaining bearings should enable the bearingof a target whose echo appears on the edge of the display to be

measured with an accuracy of ±1° or better.

· The equipment shall be provided with an angular scale around the

periphery of the display. In addition an electronic bearing line or a

mechanical bearing cursor, or both, shall be provided.

· The angular scale shall be graduated at l° 'intervals and numbered

every 10° clockwise from 000°, with 000° being the ' head-up '

position. Every 5°, scale mark shall be noticeably longer than 1° scalemarks.

· Where an electronic bearing line is provided shall:

q be clearly distinguishable from the ship's bearing marker;

q be updated at least once each antenna revolution

q have facilities to adjust its intensity

q be free to rotate both clockwise and anticlockwise continuously

every 360°, its direction of turning being the same as that of its

control. Where push button controls are used, the right or upper

shall cause clockwise rotation and the left or lower button shall

cause anticlockwise rotation.

q have a maximum thickness not exceeding 0.5° when measured

at the edge of display;

q extent from, or be capable of being extended from, its origin to

the edge of the display.

· Where a numerical bearing cursor is provided it shah not unduly

obstruct the display and shah be free to rotate both clockwise and

anticlockwise through 360°, its direction of turning being the same as

that of any associated control. It shall be possible to rotate and stop

the cursor at any given bearing within 10 seconds.

The center of the cursor shall coincide with the center of the display

bearing scale and shall be clearly marked. A line passing through this

center shall extend across the full diameter of the cursor and be readily



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identifiable. The cursor shall also be marked with a set of lines

perpendicular to or parallel with the line mentioned above. These lines

shah be at equal distance apart, approximately coincident with the

tangents to the range rings or the center and covering the effective

diameter of the display, but not exceeding to the graduated angular scale.

No other markers shall be on the cursor.

The marking of lines on the cursor shall be such as to minimize parallax

between the cursor and the face of the display and the cursor shall be

mounted such that the bearing line when turned to indicate 000° shah

cover the 180° marking within ± 0.5° and when turned to 90° shall cover

the 270° marking within ± 0.5°.

5. Discrimination

·

The equipment shall be capable of displaying as separate indicationson a range scale of 1.5nautical miles. or less, two small similar targets

at a range of between 50% and 100% of the range scale in use, and on

the same azimuth, separated by not more than 50 meters in range.

· The equipment shall be capable of displaying as separate indications

two small similar targets both situated at the same range between 50%

and 100% of the 1.5 nautical miles range scale, and separated by not

more than 2.5° in azimuth.

The Use of Nautical Publication

The masters decision on the overall conduct on the passage will be based

upon an appraisal of the available information. Such appraisal will be

made by considering the information from sources including:

q Chart catalogue

q Navigational charts and Electronic Navigation charts

q Ocean passages for the world

q Routing charts

q Sailing directions books or guide to port entry

q Tide tables

q Tidal stream atlases

q Notice to mariners

q Light lists

q Radio signaling information (including VTS and pilot service)

q Routing information



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q Climatic information

q Load - line charts

q Electronic navigation systems information

q Radio and local warnings

q Draught of vessels

q Mariner hand book

q Personal experience

The items are well known to navigator but for the purpose of

shiphandling we will get details for some of them.

a. Sailing Direction Book:

British pilot books are published in 74 volumes by the hydrographic of

the navy and give worldwide coverage. Sailing directions are published

by the defense Mapping agency (USA) in series SDPUB 121-200.Some of the books are referred to as planning guides giving information

essentially the same as the British Ocean Passage for the world, others as

enroute, giving similar information to the British Pilot Books.

b. Tide Tables:

Published by the hydrographic of the navy (British) annually, giving tidal

times and heights data, which now available by using a computer

program published by the British Admiralty.

c. Tidal Stream Atlases:

Published by the hydrographic of the navy (British), these atlases cover

certain areas of the Northwest Europe and Hong Kong

d. Notice To Mariners:

Are published in weekly addition by both the British Admiralty and US'

hydrographic authorities. Enabling ships to keep their charts and other

publications up to date.

e. Ships Routing:

Published by IMO, this publication gives information on all routing,

traffic separation schemes, deep water routes and areas to be avoided

which have been adopted by IMO. Routing information is also shown on

charts and is included in the sailing direction book.

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Reference:

1-

Ministry of Defense (Navy) - Admiralty Manual of Navigation.

Volume 1 - 1987

2- STCW 1995 - Regulation II/ I

3- Captain A.J. Swift MNI - Bridge Team Management 1993



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CHAPTER TWO

ARPA Operating Controls

Introduction

This section describes the operational controls and indicators and their

functions required to operate SHIP ANALYTICS'

RADAR/AUTOMATIC RADAR Plotting Aid (ARPA) Simulator.

Fig. (1) Radar Display

Display Monitor

The DISPLAY MONITOR used in the RADAR/ARPA SIMULATOR is

a high-resolution raster can monitor fitted with a touch-screen overlay.

During normal operation the degauss, contrast and brightness controls are

the only operational controls used. The display width height and vertical



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horizontal centering controls are only used to size the display prior to the

touch-screen calibration. Figure.(1) shows radar display monitor

Display Controls

Operational controls and indicators, with the exception of the PCcomputer and display monitor controls identified, are located on the

simulated ARPA DISPLAY. See Figure (1)

The simulated ARPA DISPLAY, shown on figure (1), provides control

and indicators for the following functional areas:

Ownship Status; Tracked Target Status; Operation Power Status; Alarm

Status; Range Scale Select/Display; Radar Display and ARPA Functions

Control; Sweep Center Position and EBL Origin Set Control; Radar

Transceiver Control; System Status; Radar/ARPA Display; and

VRM/EBL Control.

Ø

Own Ship Status Display:

The OWN SHIP STATUS DISPLAY provides a digital readout of

ownship

s current heading and log speed. When in the TRIAL

MANEUVER mode, the trial heading and trial speed will be displayed.

Ø Target Track Acquisition Symbol:

The TARGET TRACK ACQUISITION SYMBOL is used to manually

select radar returns to be tracked by the ARPA. The operator can select

and track up to 20 targets at any time.

Ø Tracked Target Status Display

The TRACKED TARGET STATUS DISPLAY will display the tracked

target's data (i.e., TARGET NUMBER, RANGE, BEARING, COURSE,

SPEED, CPA Range (+ closing and- opening) and CPA TIME (+ to and -

from)) for the target selected by the operator. With no target selected this

display is not shown.

Ø

Operation Power Status:

The STANDBY/ON control allows the operator to shift the system from

STANDBY to ON. When the system is ready for use the STANDBY/ON

display will be show with STANDBY highlighted and the system will not

display any radar returns. When ON, the ON in the STANDBY/ON

display will be highlighted and the system will display radar returns at a

sweep rate determined by the radar parameters (e.g., FREQ., POWER,



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PL, PRF, etc.) that were downloaded from the simulation host computer

during the exercise initialization.

Ø

Alarm Display:

The ALARM DISPLAY is normally blank unless a TARGET THREATor INTRUDER alarm occurs. When an alarm occurs, an alarm message

(THREAT or INTRUDER) will flash and an audio alarm will sound until

acknowledge by the operator.

×

The TARGET THREAT alarm that will occur whenever the calculated

CPA and TCPA for any tracked target is less than the set CPA LIMIT or

TCPA LIMT. The target that caused the TARGET THREAT alarm is

identified by a flashing target number and a highlighted speed vector on

the RADAR/ARPA display and the letter T attached to its target

number on the Target Designation submenu.

The INTRUDER ALARM will occur whenever the guard rings are ON

with the automatic acquisition function (AUTO ACQUIRES) OFF and a

target enters the guard ring area. On the RADAR/ARPA display, the

target that caused the INTRUDER alarm is identified with an

INTRUDER ALERT SYMBOL. When the AUTO ACQUIRES is ON,

this alarm will only occur for the targets over the 20 targets that the

system has already acquired.

Ø Range Scale Select/Display:

The RANGE SCALE SELECT/DISPLAY displays the selected range

scale to the left of the colon and range ring interval to the right (e.g., 12:

2) It also allows the range scale to be changed. The range ring interval is

non-selectable and is determined by the range scale selection.

Ø Radar Display and ARPA Functions Control:

The RADAR DISPLAY & ARPA FUNCTIONS CONTROLS display

consists of two main menus (i.e., MENU 1 and MENU 2) and submenus,

which allow the operator to make radar display and ARPA functions

selections.(Figure .2)



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Own Ship

The OWN SHIP selection allows the operator to initialize the data on the

OWN SHIP STATUS DISPLAY on a real RADAR/ARPA system. In the

RADAR/ARPA simulator own ship data is provided by the host

simulation computer provides data; and the only selection available to theoperator is the EXIT selection.

Display Orientation

The DISPLAY ORIENTATION submenu allows the operator to select a

NORTH UP, COURSE UP or HEAD UP radar display orientation.

Ø

NORTH UP is a presentation that orientates the radar display with

North at the top of the display (000o on the azimuth ring). Own ship

heading is shown at the intersection of the own ship heading flasherand the azimuth ring. All radar returns are referenced and displayed

in true bearings.

Ø COURSE UP is a presentation that initially orientates the radar

display with own ship heading and Own Ship Heading Flasher at

the top of the display (000o on the azimuth ring). The COURSE UP

display provides for the digital readouts of the radar returns to be

referenced to true bearings while the radar returns are being

displayed relative to own ship. This orientation is correct only as

long as own ship remains on the course when COURSE UP wasselected. If own ship changes course, after a course change, touch

and release the NEW COURSE selection on the system status

display to re-orientate own ship and own ship heading flasher.

Ø

HEAD UP orientates the radar display where own ship's heading is

always at the top of the display (000o on the azimuth ring). All

radar returns are referenced and displayed in relative bearings.

Intensity

The intensity submenu allows the operator to adjust the intensities of the

RADAR VIDEO, VRM/EBL, RANGE RINGS, PANEL GRAPHICS &

ARPA SYMBOLS.



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True Motion

The true motion submenu allows the operator to turn the true motion

function On or Off and manual reset. When true motion is OFF the

display is in RELATIVE MOTION where own ship is at a selected point

on the display and all targets move relative to own ship. In true motion,stationary targets are stationary and own ships and targets are displayed as

moving with their true course and speed. When own ship reaches the

outer portion of the display 75% of the display radius, the system will

automatically reset the display with own ship repositioned back to the

start point.

a.

TRUE MOTION ON/OFF allows the operator to turn true motion On

or Off.

b. MANUAL RESET allows the operator to manually reset the true

motion display anytime before own ship reaches 75% of the displayradius.

Symbol Display

The symbol display submenu allows the operator to select and/or define

display symbols. See (Figure.2)

· VECTOR TRUE/REL allows the operator to designate the vectors as

true or relative.

·

HISTORY ON/OFF allows the operator to turn the history dots ON orOFF.

· DOT INTERVAL x MIN allows the operator to set the time between

history dots.

· LENGTH x.x Min allows the operator to set the length of the vectors.

· VRM TYPE MARK/RING allows the operator to select the VRM as

either a Mark or a ring range marker when VRM-EBL is turned on.

· VRM-EBL ON/OFF allows the operator to turn the VRM-EBL symbol

ON or OFF.



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Fig. (2)

radar display main and sub menus



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Fig. (3) ARPA Display

Tracking Conditions

The tracking conditions submenu allows the operator to set the CPA and

TCPA limits that will activate the target threat alarm.

· CPA LIMIT x.x NMI allows the operator to enter the minimum range

that a target can close own ship before the alarm activates.

· TCPA LIMIT x.x MIN allows the operator to enter a time before a target

reaches CPA that will cause the alarm to activate.

Target Designation

The target designation submenu allows the operator to select what target

is to be displayed in the TRACKED TARGET STATUS DISPLAY,

notes how many targets are being tracked by ARPA, and allows the

operator to cancel targets.



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· Up to 20 target designations are available. The target designation

highlighted is the target displayed on the TRACKED TARGET STATUS

DISPLAY. Any target with the letter "T" next to it is a threatening target

(i.e., within the set CPA/TCPA limits).

· # TARGETS IN TRACK denotes how many targets are being tracked by

ARPA.· CANCEL TARGET #X (X being the highlighted target) allows the

operator to cancel this target from being tracked by ARPA.

· CANCEL ALL TARGETS allows the operator to cancel all targets,

currently being tracked by ARPA, from being tracked by ARPA.

Guard Ring

The guard rings submenu allows the operator to set up an automatic

warning system which will active the INTRUDER alarm or an automatic

acquisition mode which will automatically acquire and track when anynon-tracked target passes into a guarded area. The operator can set up to

two separate 0o to 360

o guard rings at different ranges from own ship.

· RANGE x.x NMI allows the operator to set the range from own ship to

the guard ring.

· RING START xxx DEG allows the operator to set the bearing for the

start of the guard ring.

· RING STOP xxx DEG allows the operator to set the bearing for the end

of the guard ring.

· RING ON/OFF allows the operator to turn the guard ring ON or OFF.

·

AUTO ACQUIRE ON/OFF allows the operator to select a automatic

tracking of an INTRUDER target. When ON, an INTRUDER will be

automatically tracked, when OFF or when all 20 targets are being

tracked, the INTRUDER alarm will activate and the INTRUDER ALERT

symbol will flash but the target will not be automatically tracked.

· SELECT GUARD RING x allows the operator to switch between guard

ring #1 and guard ring #2 controls.

Trial Maneuver

The TRIAL MANEUVER submenu allows the operator to evaluate the

effect of an own ship speed and/or course maneuver before the ship

actually maneuvers. When activated, vectors for all tracked targets are

calculated and displayed from the own ship speed and course data entered

by the operator. This mode is useful for evaluating own ship maneuvers

in crossing traffic, where avoiding one traffic ship might cause a closing

situation on another traffic ship. When in the trial maneuver mode, a large

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"T" appears on the screen and TRIAL HEADING and TRAIL SPEED are

indicated in the OWN SHIP STATUS DISPLAY.

· HEADING xxx DEG allows the operator to enter an own ship course.

· SPEED x.x KTS allows the operator to enter an own ship speed.

· TRIAL ON/OFF allows the operator to turn the trail maneuver ON

and OFF.

Radar Controls.

The radar control submenu allows the operator to select either AUTO or

MANUAL tuning capability in the radar transceiver control section. In

the RADAR/ARPA simulator the only selection available to the operator

on the radar controls submenu is the EXIT selection.

Menu 2

The MENU 2 selection allows the operator select Menu 2 and its

submenus for display.

Radar Test Mode

The radar test mode submenu provides simulated targets to be displayed

on the screen and allows the operator to perform operability and system

readiness tests. In the RADAR/ARPA simulator the host simulator

computer provides this function and the only selection available to the

operator on the radar test mode submenu is the EXIT selection.

Display Options

The display options submenu allows the operator to adjust the display

monitor's background color. In the RADAR/ARPA simulator the only

selection available to the operator on the display options submenu is the

EXIT selection.

Calibrate Touch

The calibrate touch submenu allows the operator to align the touch screen

to the display.



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Menu 1

The MENU 1 selection allows the operator selects Menu 1 and its

submenus for display.

Sweep Center & EBL Origin Set Control:

THE SWEEP CENTER & EBL origin set control section provides

controls for the display of own ship's position and electronic bearing line

(EBL).

q CENTER allows the operator to position own ship as the center of the

display.

q OFF CENTER allows the operator to display own ship off centered

from the center of the display.

q EBL HOME allows the operator to reset the origin of the EBL to the

home own ship's position.q EBL OFFSET allows the operator to offset the EBL origin to any point

on the display.

Radar Transceiver Control:

The radar transceiver control section allows the operator to make

simulated adjustments to the radar receiver to improve the radar display.

· PWR PULSE allows the operator to simulate an increased transmitted

pulse width. The effect of this control is to optimize the detection of

small targets in sea clutter. This control is not available for rangescale selections of 24 nm and above.

· AUTO TUNE is a fixed control for the tuning of the receiver local

oscillator. MANUAL control is not available.

· GAIN allows the operator to simulate the adjustment of the overall

receiver gain.

· SEA allows the operator to simulate the adjustment of the receiver's

STC setting. The effect of this adjustment is to reduce the clutter

produced by heavy rain.

· RAIN allows the operator to simulate the adjustment of the display's

background level.



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System Status Display:

The system status display section provides a NEW COURSE reset control

and several system status displays.

· NEW COURSE is displayed only when the selected display orientation

is COURSE UP. In COURSE UP, own ship's heading was initiallyorientated to 000 on the azimuth ring. If own ship's heading changes,

the indicated course will no longer be referenced to 000. To

reorientate own ship's new course to 000, touch and release NEW

COURSE.

· NORTH UP, COURSE UP, or HEAD UP indicates the selected

orientation of the radar display.

· RELATIVE MOTION or TRUE MOTION indicates the selected

display mode for own ship's motion.

· TRUE VECTOR MIN or RELATIVE VECTOR MIN indicates the

target vector status and the time length of each vector line.· CPA LIMIT NMI indicates the set range for the closest point of

approach. When a target reaches the CPA LIMIT the TARGET

THREAT alarm activates.

· TCPA LIMIT MIN indicates the set time to the closest point of

approach. When a target reaches the TCPA LIMIT the TARGET

THREAT alarm activates.

Radar/ARPA Display:

The RADAR/ARPA display is a graphic representation of a Plan position indicator (PPI) display, consisting of an outer azimuth ring

and inner range rings, which display the radar picture 360o around

own ship. The fixed azimuth ring denotes bearings, while the innerconcentric range rings, the number of rings dependent on the

selected range scale, denotes range distances from own ship.

VRM/EBL Control:

The VRM/EBL control section displays the range from the EBLorigin to the mark designated on the VRM position and the bearing

from the EBL origin to the mark designated on the EBL line. TRUEis displayed when NORTH UP or COURSE UP orientation is

selected. RELATTVE is displayed when HEAD UP orientation is

selected.



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Graphics & Symbols

To assist the operator in the identification of various display features the

RADAR/ARPA simulator display provides graphics and symbols, shown

on (Figure. 4), associated with RADAR & ARPA functions.

Azimuth Ring:

The azimuth ring is the fixed outer ring graphic on the radar display. The

ring is graduated in one-degree increments and marked in ten-degree

increments.

· With NORTH UP/OWN SHIP CENTERED display selected, the true

heading of own ship's course and the true bearing of targets, intersected

by the EBL, are determined directly from the scale on the azimuth ring.

· With COURSE UP display selected, the display is initially rotated so

that 000 represents own ship's course and relative bearings can bedetermined from the scale on the azimuth ring.

· With HEAD UP display selected, the radar display is rotated so that 000

always represents own ship's bow and all bearing are relative to own ship

and can be determined from the scale on the azimuth ring.

Fig. (4) Symbol Display Of ARPA & Guard Rings



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Range Rings:Range rings graphics will display three, five or six concentric rings

depending on the selected range scale. The distance between the range

rings is displayed on the RANGE SCALE display (to the right of the

colon). Range eings will always remain concentric with own ship s

position in both CENTERED and OFF centered modes.

Guard Ring:The guard ring symbols represent an area set up by the operator as an

alert area. One or two guard rings can be established either in an arc or a

complete circle around own ship.

If any non-tracked target enters an area set by guard ring, an INTRUDER

alert will be display in the alarm display area and a flashing INTRUDER

symbol are displayed ON.

The target acquire mode is selected; the target entering the guard ring will

be automatically acquired and tracked.

Intruder Alert Symbol:The intruder alert symbol, associated with guard rings, is displayed on

any non-tracked target that enters a guard ring area.

Own Ship Indicator:The own ship indicator is a cross - located at the origin of the Own Ship

heading flasher.

Tracked Target Number:Any time a target is selected for tracking the system will assign a number

to the target. The number is displayed near the target tracking windowand is added on the target designation menu. The target number will

flash whenever it is a threatening target (i.e., within the CPA/TCPA

limits).

History Dots:The history dots symbols show the previous positions of a tracked target.

The spacing between history dots indicates the distance traveled and is

controlled by the DOT INERRVAL x NIN selection.

VRM Mark or Ring:The VRM Mark (+) symbol indicates the range of a selected point on the

EBL. A ring range marker can be selected instead of the EBL mark

symbol.



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Electronic Bearing Line:The electronic bearing line (EBL) is a reference line that can be set to

start at any position on the display and extended, in a straight line, to any

other point on the display. The orientation of the line provides the

bearing between the two points. Regardless of whether the EBL is

centered or OFF centered, it provides true bearing when NORTH UP orCOURSE UP orientation is selected and relative bearing when HEAD UP

orientation is selected.

Tracking Window:The tracking Window symbol, two short parallel arcs, brackets each

target in track.

Target Speed Vector:The target speed vector is displayed in all orientations when selected from

the SYMBOL DISPLAY menu. When selected, a vector whose lengthand direction represent the target's predicted motion is displayed from

each tracked target. The target speed vector will highlight whenever it is

a threatening target (i.e., within the CPA/TCPA limits).

Own Ship Speed Vector:The own ship speed vector extends outward from own ship's position and

indicates own ship s speed and heading. The length of the vector is

scaled to represent the distance; that own ship will travel in the time

interval (Length x.x NIN) entered by the operator on the symbol

submenu. The own ship speed vector is a true vector and it is notavailable when vectors are selected.

Own Ship Heading Flasher:The own ship heading flasher symbol is a line that extends outward from

own ship's position along own ship's heading to the azimuth ring. When

NORTH UP CENTERED is selected, own ship's heading can be

determined directly from the azimuth ring.



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CHAPTER THREE

Blind Navigation

Blind navigation means navigation through restricted water in low

visibility. The master should remain on the bridge and conduct the

navigation. It is desirable; if possible, to have two watch officers to backup the master on the bridge, watch officer no.1 to man radar No. 1 (3 cm.)

to monitor the navigation. Watch officer No.2, if available, mans radar

No. 2 (10 cm), if provided, he has the primary duty of developing and

reporting collision avoidance information.

If only one radar is available this has to be used for both navigation and

collision avoidance and a safe speed is then possibly slower than when

two radars are in use.

The composition and duties of the bridge team in this situation must

therefore have sufficient flexibility built in to cope with suchcircumstances. The master may continue to con the ship from the

compass platform, in case of blind navigation situation arises

subsequently, taking full account of the navigational and collision

avoidance information he is receiving from the watch officers on radar

displays and lookouts.

The ship must be accurately along a pre-arranged track. The delays

inherent in fixing are unacceptable. It is necessary, for anti-collision and

navigation in these conditions, to work directly from the radar display

using a prepared notebook; but it is still necessary to pass, radarinformation for fixing regular intervals as a safety check as an insurance

against radar failure.

Blind and visual selected track should be the same, to enable the

transmission from visual to blind or vice versa to be made at any time and

also to allow one plan to be used to cross check the other. Consideration

mentioned for navigation under pilotage should be applied. Stress should

be made on the following:

1)

The number of the course alterations should be kept to a minimum toreduce the workload in redrawing and 'wheel over lines.

2)

Parallel index technique is a simple and most effective way of

continuously monitoring a ship's progress in restricted waters.

3) Two parallel index lines could be used, where possible, one on each

side of the track.



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4)

Objects to be used both f or parallel index lines and for fixing must be

carefully selected. They should be radar-conspicuous and unchanged

by varying heights of tide. They should be marked on the charts.

5)

The range scale to be used requires careful consideration. Changes ofrange scales and parallel index marks should be pre-planned and noted

in the notebook.

6) Expected sounding (allowing for height of tide and calibration of echo

sounder) should be noted for each leg.

7)

All hazards along the track; should be boxed in by clearing ranges and

their cross-index ranges listed in the bridge notebook.

8)

Details of lights and fog signals should be entered in the bridgenotebook.

Parallel Index Technique

Investigation of casualties involving the grounding of ships, when radar

was being used as an aid to navigation, have indicated that a factor

contributing during the period of time leading up to the casualty.

Valuable assistance plan could have been given in such cases if the bridge personnel had used the techniques of Parallel Index Plotting on the radar

display. Such techniques should be practiced in clear weather during

straightforward passages, so that bridge personnel become thoroughly

familiar with this technique before attempting it is confined and difficult

passages, or at night, or in restricted visibility.

The basic principle of Parallel Index Plotting can be applied to either

Ø

A stabilized relative motion display or;Ø A ground-stabilized true motion display.

1.

On a stabilized relative motion display the echo of a fixed object will

move across the display in a direction, which is the exact reciprocal

of the course made good, by own ship at speed commensurate to that

of own ship over the ground. A line drawn from the echo of the

fixed object tangential to the variable range marker circle set to the



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desired passing distance will indicate the forecast track of the echo

as own ship proceeds. If the bearing cursor is set parallel to this

track it will indicate the course to made good for own ship. Any

displacement of the echo from the forecast track will indicate a

departure of own ship from the desired course over the ground.

2.

On a ground-stabilized true-motion display, the echo of a fixed object

will remain stationary on the display (own ship) will move along the

course made good by own ship at a speed commensurate to that of

own ship over the ground. A line should be drawn form the echo of

the fixed object tangential to the variable range marker circle set to

the desired passing distance. If the electronic bearing marker is set

parallel to this line it will indicate the course to be made good by

own ship over the ground. The drawn line not being tangential to the

variable range circle will indicate any departure of own ship from

this course. (The variable range marker circle should move along theline like a ball rolling along a straight edge).

I.

The navigation line or offseting of electronic bearing line

cursor can be used as an aid to drawing the Index Lines

II. It should be borne in mind that Parallel Indexing is an aid to

safe navigation and does not supersede the requirement for

position fixing at regular intervals using all methods available to

the navigator.

III. When using radar for position fixing and monitoring, check:

Ø The radar's overall performance;

Ø The identity of the fixed object(s);

Ø Gyro error and accuracy of the heading marker alignment;

Ø Accuracy of the variable range marker, bearing cursor and

fixed range rings;

Ø On true motion, that the display is correctly ground-

stabilized."



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The parallel index technique offers the possibility of a continuous check

as to whether the ship follows the planned track (over the ground). The

method may be applied at night as well as in daytime, and in restricted

visibility. The only prerequisite is the presence of an echo of a known,

charted and fixed conspicuous target on the radar screen.

Before using parallel index technique:

It is important that the following items are checked before using parallel

index method:

Ø The radar's overall performance.

Ø

Centering error (can be corrected by X-Y shift).

Ø Fore and aft line of radar not coinciding with fore and aft line of

ship.

Ø

Heading marker bearing scale error.Ø Gyro error.

Ø

Azimuth stabilization error.

Ø

Electronic bearing indicator index error.

Ø Variable range marker index error.

Ø

In true motion it should be ensured that the display is correctly

ground stabilized.

When applying the parallel index method, it is recommended to use the

radar in its relative motion, mode.

*There are four reasons for the requirement of sing relative motion

made

I. On True Motion (TM), with an unknown drift and leeway, the ship

will be moved off the PI-track, and the echo of the fixed point will

move as well. This must be checked continuously and can be

corrected by the x-y shift. On Relative Motion (RM) this problem

does not exist and one need only concentrate on the PI-track and the

echo.

II. Drawing a PI-track on the reflex plotter beforehand is impossible on

TM without adjusting the x-y shift afterwards due to the still

unknown location of own vessel on the screen. On RM the

previously planned PI-Track may be drawn on the reflex plotter.

III. In view of the "Rules of the Road", it is recommended to use radar in

R.M.



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IV. A weak echo of an object dead ahead might not be noticed on TM

because the PI-track on the reflex plotter goes right over it. This

objection does not exist on RM.

Limitations of parallel index techniques:

There are two important limitations to be remembered when using Parallel

Index Techniques for piloting.

1. Instrumental Errors.

2. Nature of the Observed Object.

Instrumental Error:

The maximum error, allowed by the specification of a D of T type-Tested

set, depends on the Range-scale in use as follows:

Ø

6-mile range-scale: 256 meters (0.14 mile)

Ø

3-mile range-scale: 128 meters (0.07 mile)

Ø 11/2-mile range-scale: 85 meters. (0.05 mile)

Ø

3 /4 mile range-scale: 74 meters (0.04 mile)

N.B.

Integrating range and bearing errors have found the above possible errors.

(1 .5 % of max. range ... etc., and ±1o

). Note also that there can be additional observational errors (including

failure to check for faulty equipment) particularly if using un-stabilized

Radar Presentation, i.e. it is best to use North-Up Stabilized Relative

Motion.

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Nature of the observed object:

Accuracy depends on the size and shape of the object and whether it is a

fixed or floating. An ideal is Monkstone Beacon because it is reasonably

small, isolated and fixed (beam width and pulse length distortions

reference point). Less favorable objects are edges of headlands...(Monkstone Beacon is a lighthouse on a rock in the Bristol Channel,

U.K.)

Fig. 1 Fixing by Radar Range and Bearing.



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Use of A Radar Clearing R ange

When proceeding along a coast, it is often possible to decide on a

minimum clearing range outside which no off-lying dangers should be

encountered. The clearing range is illustrated in (Fig. 2), and may also be

drawn on the display using the parallel index technique. The ship mustremain outside the clearing range to proceed in safety.

Fig. 2 Use of a Radar Clearing Range



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CHAPTER FOUR

Electronic Charts & Display Information Systems

(ECDIS)

Introduction

ECDIS is a system, which integrates from the global position system

(GPS), a ship speed log, gyrocompass, and radar, using electronic charts.

It was a great step in technology of navigation due to its compact size on

the bridge and its various uses. ECDIS is linked to the autopilot, so

officers can monitor all the activities without having any trouble on the

displays of all the ECDIS. In order system mariners used to draw the

courses on paper charts, using pencil, dividers, and parallel rules, but now

using ECDIS it's done on electronic display using trackball and key

strokes. Their charts will actually be geographic data stored as connected

points that a computer reassembles to show where the ship is and what

surrounds it.

With in a few years ECDIS is expected to become a legal replacement for

the paper copies of official hydrographic charts that all the ships carry

nowadays. Standards of ECDIS where finalized by the international

maritime organization (IMO), and the international hydrographic

organization (IHO), Monaco, London.

ECDIS is only one piece of equipment among many on the bridge of

modern ships. It simplifies many jobs for the navigator and makes itmuch easier. For navigators, ECDIS represent and item of equipment

consisting of hardware and software, it integrates data from:

GPS, Radar, Gyrocompass, Echo Sounder & Speed Ship Log through

interfacing.



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The software that enables the computer to be an ECDIS consists of the

user interface and the so-called ECDIS kernel.

The major goal of this chapter is to show what is meant by interfacing,

what kinds of interfacing used, what are the main uses of interfacing in

our project. The following items interfaced to the ECDIS are shown in the

Figure.(1)

Fig.( 1)



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Fig. (2)



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LIST OF ABBREVIATIONS

AMVER

.. Automated Manual-Assistance Vessel Rescue

SystemARPA ... .. Automatic Radar Plotting Aid

COLREG .. .. Collision Regulations

CPA Closest Point of Approach

D.W .Dead Weight

EBL . .Electronic Bearing Line

EPIRB

...

.. Electronic Position Indicator Radio Beacon

ETA

...

.. Estimated Time of Arrival

ETD

. Estimated Time of Departure

IALA

International Association of Light House

Authority

K.TON .. . 1000 Ton

K.W . ... Kilowatt

MERSAR

... Merchant Ship Search & Rescue

MPP

. Most Probable Position

OOW

Officer of The Watch

P.I

Parallel Index

P.R.F

.

.. Pulse Repetition Frequency

PC

... Personal Computer

PPI Plan Position Indicator

RPM Revolution Per Minute

SAR . ... Search & Rescue

SOLAS

.

.. Safety of Lives at Sea

STCW

.

Standards of Training, Certification & Watch

keeping At Sea



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TSS

.

Traffic Separation Schemes

UMS

.

.. Unmanned Machinery Space

VRM

.

.. Variable Range Marker

-

.

.. Astern

+ .. Ahead

0 ... Stop

1 .. Full Speed

1/2

.

.. Half Speed

1/4

Slow Speed

1/8

.

.. Dead Slow Speed

<

.. (m.m) Main Menu

. . (s.m) Sub Menu

VGA . .. Video Graphics Adaptor On The Computer

PALRGB . ... Red, Green, Blue System By Cables To Display

On Or Projectors

QUAD Tree

Type of Structure Data

K-Dimensional Tree

... Multi System of Data Structure

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ECDIS Features

Geographic information system (GIS) techniques have been used to

provide additional safety and data access function, creating a basis from

which the chart can be expanded into an intelligent decision support tool.For example, an automatic grounding warning system has been

implemented which sounds an alarm if the charted depth at the ship's

Position falls below a predetermined value.

This approach is shoe to provide a through and complementary approach

to current navigation methods, gives new opportunities in safety and

control and easy it use by mariners of varying experience in a full range

of navigational environments. This design philosophy describe the

objectives of the technology to:

1. Reduce the navigational workload of officers by direct interfacing of

chart display and position systems, automating the process of chart

work and provision of rapid acres to supporting publications, and to

allow the automatic updating of charts and publications by means of

satellite link and magnetic disk.

2.

Improve safety at sea by providing automatic generation of navigation

information, for example by using spatial data access to give warning

of possible grounding.

3. Provide an application of information technology to the maritime

industries to improve commercial performance through cost savings.

ECDIS has a significant impact on navigation control and permit safe

reductions in manning level, in commercial shipping.

The technical description of the charts is based upon PC compatible

computers. The hardware platform permits the use of standard

commercial software libraries. Communication interfacing to other

associated hardware, for example positioning devices and exciting ship

equipment takes place via three-channel asynchronous commutationdevice. A vital competent of the system is the multimedia expansion card

which converts PAL RGB video to VGA line display standard and

provides a graphics overlay facility. Video images are stored sequentially

as single frames on a laser vision videodisk to which random access is

provided by a laser disk player. Two screens are used as output devices;

one for the chart images, the other is monochrome for the display of

textual information.



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A degree of multi-tasking is incorporated to enable continuous position

monitoring, display refresh and logging functions to operate concurrently

with the user's inputs, which are monitored, by a trackball and keyboard.

Specially developed software libraries provide graphics routines and

window/menu functions. A relational database has been developed using

a memory resident driver for data insertion and retrieval operations.Either a commercial GPS receiver provides ship-positioning input or via a

dedicated link with a training shore simulator, which allows either sea or

shore, based testing.

System Operation

· The chart display:

The chart display is a screen on which the video images of the source

charts are displayed. A cursor controlled by a trackball is used to directthe frame handling, its geographical lat / long position being updated

continuously as the trackball is moved. Changes of frame occur when the

cursor crosses the current frame boundary and when the user operates the

zoom in / zoom out function keys. The photographs are provided at two,

levels, comprising images shot from different camera heights allowing

two stages of zoom. This gives the user the opportunity to view the

general topography of the charted area on the wide focus frames and the

ability to read the full detail on the chart where required on the close up

frames.

During zoom operations, which are centered, on the cursor location, the

display alternates between these levels and changes of scale accrue when

display the request can't be met within the current chart. Switching to the

next chart covering the area of interest does this. The cursor remains as

closely centered as possible on the same lat/long position allowance being

made for differences in the ratio of the pixel area to area in the charted

terrain. After the new chart has been displayed, a scale change warning is

briefly shown and the scale bar at the chart edges redrawn. All overlaid

information such as course lines, the range and bearing indicator etc, are

redisplayed appropriately. Considerable care has been taken to achieve asatisfactory degree of chart accuracy.

The data preparation algorithms have to account for the chart projection

spheroid and datum. Supporting data is stored file to provide system

information concerning the chart projection, its horizontal datum, the

chart title number, last correction and date of production.



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The provision of chart cor rections is being prototype using graphical

overlays. Each chart will have its own set of corrections, which will be

automatically loaded and displayed each time the chart is used. The data

format supports chart corrections and it will be from this source that they

will be provided within the system. It is anticipated the chart corrections

will be sent to chicks either on a floppy disk or via a satellitecommunication system. The way in which the chart display is used is

determined by whether the system is in its in passage planning or

navigation modes of operation.

The passage-planning mode allows the user to define a route as a service

of waypoints. This are placed on the chart directly using the graphics

cursor. No lat/ long keyboard inputs are required. Further, routines allow

the addition, deletion, movement and insertion of waypoints. With a brief

description of the route being mentioned on the information screen. The

description takes the form of the course and distance along each leg,or the form of the leg descriptor field provided for users comments.

The track should validate by visual inspection.

It is intended to automate this using the grounding warningmechanism mentioned earlier. It is also intended to prototype an

automatic annotation features using similar method, which will

provide commentary consisting of the features along each leg in aform, appropriate to the stage of the voyage being considered. Such

a track commentary technique could be considered as analogs to,

activity pre-processing data in the form of a navigator s notebook.In general, the chart with in the system is classified as belonging to

one of three major types: harbor, coastal and ocean.

The form of the commentary and the type of information it generates

will depend on the chart type being used, for example, the

commentary relating to the use of a harbor chart will contain detailrelating to the planned track as follows: detail of charted soundings

at regular intervals, all buoys encountered, all relevant navigational

lights, visual land marks ashore, safe track width, wheel over positions, radio reporting points and clearing bearing, etc.

In contrast, the commentary relating to the use of a costal chart will

be more concentrated with: safe maximum cross track error, majorlights, buoys and fog signals, traffic separation schemes and



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regulations, radar conspicuous points, descriptive extracts from

sailing directions, etc.

The navigational mode is used whilst on passage. Positions are

received from GPS receiver using unmodified standard position

service data, and a continuous readout of course made good, Speedmade good, distance to waypoint, bearing waypoint, and time towaypoint is maintained in a special area on the information system

screen.

Successive track Legs are selected by the user using a menu system asthey become current. The position of own ship is displayed continuously

on the chart and it is possible to allow the vessel's progress to control the

frame handling. At rack history is displayed of positions recorded at 30s

intervals over 15 min period. In the event of an emergency this would berecorded as instantly to provide a moment-by-moment account of the

vessels movements. Emergencies might be detected automatically via

other interfaced NAVAIDS such as the ARRA or echo sounder.

At present the ships position is automatically recorded to disk every 15

min. The recording interval might be altered according to the operating

area of the vessel, since this again illustrates the need to apply the varying

degrees of control in different navigational circumstances.

Whilst navigation mode, it is intended to apply a further level of controlthrough a system setting, which will govern the behavior of certain

functions according to, whether the vessel is an pilotage, coastal or open

waters. The watch-keeping officer will manage the transitions between

the conditions.

Using a set of check-off. It is often the case that navigational accidents

accrue during these changes of circumstances due to a poorly managed

response to the new workload and risk. This can lead to a failure to

ensure the ships are materially prepared for the new conditions in which

they find them selves.

This type of technology will also allow a video output of the currently

active chart display to be maintained in, say, the masters accommodation,

allowing him to monitor safety critical information in locations remote

from the bridge, giving another level of safety of monitoring.



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ship handling & manovering course_part b.pdf

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