1

PREFACE

All thanks to ALLAH S.W.T for by His Grace and Mercy, this Quick Reference of (QR700) has been successfully published. This Navigation-QR is published as a guide and reference to all the officers and staff of the Malaysian Maritime Enforcement Agency (MMEA) that attends courses or training at the Akademi Maritim Sultan Ahmad Shah (AMSAS).

This book has been arranged and edited through reference to certain related navigation publications to facilitate it’s readers to understand and refers swiftly and with ease. It also aims to reduce the dependency on other books of references that involve large expenditure to obtain.

In addition to that, it serves as a guide to the instructors in disseminating the relevant knowledge to course participants and trainers. In assisting educators and trainees, AMSAS is moving towards publishing various other Quick reference for each subject that is being taught in AMSAS to provide course participants and trainees an easy guide and simple reference.

On behalf of the management of AMSAS, I wish to convey my deepest appreciation to those who have put in a lot of effort to produce this QR700. It is hoped that this guidance will benefit all MMEA officers and staff especially those attending courses in AMSAS.

With Best Regards,

FIRST ADMIRAL (M) DATO’ MOHD TAHA BIN IBRAHIM

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TABLE OF CONTENTS

Page PREFACE CHAPTER 1: POSITION AND DIRECTION ON THE EARTH’S SURFACE 1.1 Longitude and latitude 1-3 1.2 Unit of measurements 4 1.3 Magnetic Variation 4

CHAPTER 2: CHART 2.1 Distinguishing a well surveyed chart 5 2.2 Coordinates and positions 6 2.3 Selection of chart symbols 6 - 7 2.4 Aids to navigation 8 - 9 2.5 Lateral Marks - direction of buoyage 10 - 11 2.6 Cardinal buoys 11 - 12 2.7 Marks indicating isolated dangers 12 2.8 Marks indicating safe water 12 - 13 2.9 Marks for new wrecks 13 - 14 2.10 Special buoys and marks 14 - 15 2.11 Chart symbols 15 2.12 Two distinct types of sea mark are drawn differently 15 - 18 in the chart

CHAPTER 3: CHARTWORK 3.1 Position Lines 19 3.2 Fixing 19 3.3 Chart work Planning symbols 20 3.4 Example for Coastal Navigation 21 3.5 Dead Reckoning (D.R) 22 3.6 Clearing bearings 22 - 23

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CHAPTER 4: THE PILOTAGE PLAN 4.1 Introduction 24 4.2 Selection of the track 25 - 34 4.3 Execution of Pilotage 35 4.4 Error in the Compass and Eliminating the 35 - 37 Cocked Hat 4.5 Tide 37 - 38 4.6 Chart datum and land survey datum 39 - 40 4.7 Anchorage 40 - 46

CHAPTER 5: BLIND PILOTAGE 5.1 Introduction 47 5.2 Blind Pilotage Planning 48 - 51 5.3 Blind Pilotage Execution 51 - 53 5.4 Radar calibration (Index Error) 53 - 54 5.5 Two-mark method 54 - 55 5.5 Three-mark method 55 5.6 Conning and Control Orders 57 - 58

CHAPTER 6: RELATIVE VELOCITY (RELVEL) AND COLLISION AVOIDANCE 6.1 Introduction 59 - 60 6.2 Principles of Relative Velocity 60- 62 6.3 Initial position of ship 62 6.4 Relative movement 63 6.5 The velocity triangle 63

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6.4 Relative movement

When considering relative tracks, do not make the mistake of assuming that a ship points in the direction of her relative track. She is still pointing in the direction of her course, which may be very different. Visually, a ship often appears to move almost sideways, or crabwise, along her relative track.

6.5 Relative velocity triangle

Once the relative track and speed of the other ship have been found, a velocity triangle (fig. 17) may be used to give the other ship’s take track and speed. Alternatively, the velocity triangle maybe used to find the relative track once the true track has been determined is known.

Fig. 17

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CHAPTER 1 c. If own ship is obliged to alter course to give way to another, POSITION AND DIRECTION ON THE EARTH’S SURFACE it is important to be able to assess what effect this maneuver will have on the relative track of other ships nearby. For ex- 1.1 Longitude and latitude ample, own ship W may consider altering course 30° to star- board to avoid another ship G. 1.1.1 The earth can be regarded as a spherical object, and since we're dealing with a 3-dimensional shape we need coordinates of a different form than the usual x- and y-axes. Though adding extra z-axes would make sense for submarines, we will most

likely be found on the surface of this sphere while using another

system of coordinates, that covers our planet with imaginary lines called meridians and parallels, see figure 1. All these lines together provide the grid which enables us to describe any position in longitudes and latitudes.

d. The plotted track GJ is G’s true track and speed (300°, 15 knots). It should be noted that this is very different from G’s relative track and speed (208°, 12.7 knots).

6.3 Initial position of ships

1.1.2 The obvious place to divide the Northern and Southern Hem- The initial positions of the ships do not affect the velocity ispheres was the equator. But the division of the Eastern and triangle, which depends only on the tracks and speed of each Western hemispheres was the source of much political tur- ship. However, the initial positions of the two ships will have very moil. Greenwich (Great Britain) won, placing for example The different effects on subsequent events. Suppose that, the other Netherlands in the Eastern and Ireland in the Western Hemi- ship G had started from a position K on a bearing of 028° from sphere. own ship, instead of starting from position G. Her relative track of 208° must then pass through the position of own ship. G is therefore on a collision course.

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6.2.2 Relative track and relative speed 1.1.3 It takes the earth 24 hours for a full rotation of 360°. Thus, every hour we rotate 15° longitude, see figure 2. a. Relative speed is also dependent upon the courses being steered by each ship. For example, if the two ships are steam- 1.1.4 When it is 12:00 UTC (international standard time) - anywhere ing in station with one another on the same course and in the world - it is 12:00 Local Time in Greenwich and 24:00 Lo- speed, then the speed of one ship relative to the other is ze- cal Time at the other side of the planet: 180° E or 180° W: the ro. In order to avoid collisions between ships and also to ma- date line. Crossing this special meridian changes not only the neuver ships in company safely, the terms relative track and hour but also the date. relative speed must be understood. In Fig. ship G is in sight on the starboard bow of own ship on a crossing course. 1.1.5 The North Pole has latitude of 90° N and the South Pole 90° S. If the true bearing between the two ships does not apprecia- The meridians cover twice this angle up to 180° W or E. bly change, then in accordance with Rule 7 of the Internation- Meridians converge at the poles, whereas parallels run parallel al Regulations for Prevent Collisions at Sea, 1972 (the Rule of to each other and never meet. the Road), a risk of collision must be deemed to exist. (In such a case, under Rule 15, own ship W is required to give 1.1.6 All meridians and the equator - the biggest parallel - form great way to ship G.) circles, and the remaining parallels form so-called small circles. A great circle divides the earth in two exact halves.

1.1.7 In figure 3 the position of Boston in the United States is shown

using latitude and longitude in degrees, minutes and seconds: 42° 21' 30" N , 71° 03' 37" W

Fig. 16

b. If the true bearing of G from W remains steady, then to the Officer of the Watch in W, G must appear to be approaching W along the line GW. In other words, the track of G relative to W (the relative track of G) is GW. The relative speed is that speed at which G is approaching W along the line GW. Fig. 16 illustrates the case of one ship in sight, crossing, and on a steady bearing. The collision avoidance problem is easy to solve because the bearing is steady; the relative track does not have to be computed.

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1.1.8 Most sailors will actually notate seconds in metric fractions of minutes: 42° 21, 5’ N, 71° 03,6' W or 42° 21.5' N , 71° 03.6' W,

On small scaled charts we want to be accurate within one minute

or one nautical mile. On larger -- scaled charts the accuracy is more likely to be within a tenth of a mile (a cable).

6.2 Principles of Relative Velocity

6.2.1 Relative speed

a. Suppose two ships are approaching each other head-on, the

speed of each being 20 knots (Fig. 15). 1.1.9 If the earth were a perfect sphere with a circumference of rough- ly 40000 kilometers all great circles - meridians plus the equator - would have the same length and could be used as a distance unit when divided into 360 degrees, or 360° x 60' = 21600' minutes.

In 1929, the international community agreed on the definition of 1 international nautical mile as 1852 meters, which is roughly the average length of one minute of latitude i.e. one minute of arc along a line of longitude (a meridian). Fig. 15

1.1.10 Or to put it shortly: 1 nm = 1'. The earth rotates from West to

East. Thus, 1 degree = 15 minutes – the sun’s travel. b. Own ship may be represented by WO, the other ship by WA. The speed of one ship relative to the other is 40 knots; in other words, to an observer in one ship the other ship

appears to be approaching at a relative speed of 40 knots. This relative speed may be represented by OA. One arrowhead is used on own ship’s vector, two on the other ship’s vector and one arrowhead in a circle on the relative motion vector.

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1.2 Unit of measurements CHAPTER 6

RELATIVE VELOCITY (RELVEL) AND COLLISION AVOIDANCE

1NM = 10 cables

6.1 Definitions 1NM 1852 metres

1NM 6080 feet Various terms are commonly used in the context of relative veloc- 1NM 67.56 shackles ity and collision avoidance and also when other ships are being plotted on radar. These terms are set out below: 1NM 1200 fathoms

1 shackle 90 feet SEA SPEED The speed of own ship along the water track, 6 feet 1 fathom expressed in knots. 120 fathoms 1 cable GROUND SPEED The speed of own ship along the ground track, expressed in knots. 1.3 Magnetic Variation RELATIVE TRACK The path of a radar contact as observed on a OF CONTACT surface plotting table or on a true motion display

TRUE TRACK OF The path of a radar contact as observed on a sur- CONTACT face plotting table or on a true motion display. Compass Rose

ASPECT The relative bearing of own ship from another ship, expressed in degrees 0 to 180 Red or Green relative to the other ship (Fig. 17-1). Aspect is often referred to as angle on the bow.

DETECTION The recognition of the presence of a radar contact. 1.3.1 The following rule should be applied for the conversion of magnetic or compass courses and bearings to true: ACQUISITION The selection of those radar contacts requiring a tracking procedure and the initiation of their tracking. a. Easterly variation and deviation are added or applied clockwise. TRACKING The process of observing the sequential changes b. Westerly variation and deviation are subtracted or in the position of a radar contact to establish its motion. applied anti-clockwise.

1.3.2 This rule may be memorized by the mnemonic CADET

C AD E T Compass Add East True

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CHAPTER 2 5.7.3 Propulsion Conning Orders CHART Propulsion Conning orders may be divided into three categories and their use will depend on what propulsion control instruments are fitted. 2.1 Distinguishing a well surveyed chart

2.1.1 Source data diagrams (see Figure 4 below) are the key to how a. Engine Orders. Engine orders are used to order the well the area shown on the chart has been surveyed, bearing in direction and overall amount of propulsion thrust. They are mind on lines of soundings and wrecks. If such information is not passed by Engine Telegraph. Engine orders comprise available, then bear in mind the following points: combinations of the following terms: Ahead, Astern and a. The survey should be reasonably modern (see date given Stop, Slow, Half, Full.

in title notes). b. Power Orders. Power orders are used to order the b. Soundings should be close together, regular, with no propulsion power (and sometimes direction) and are passed blank spaces. by Pitch-Power Control Lever (PCL) settings or shaft rev- c. Depth and height contour lines should be continuous, not broken. olutions using a Lever, Percentage or Revolution order in- strument of some kind. d. Topographical detail should be good.

e. All the coastline should be completed, with no pecked c. Shaft Brake Orders. Shaft Brake orders are used to stop a portions indicating lack of information CPP shaft from rotating by applying the Shaft Brake, or to

release the Shaft Brake. A variety of different control

instruments exist to apply and release the Shaft Brake and

the implementation procedures and orders vary by class.

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b. Alterations of Course over 20°. When altering course 2.2 Coordinates and positions

by more than 20°, it is usual to include the intended course 2.2.1 A pair of nautical dividers (single handed dividers) is used to with the initial order. The sequence of orders given by the obtain precise coordinates from the chart. This device enables OOW is then as follows: you to take the distance between that particular position and the

closest grid line. You then place the dividers on the scale with i. OOW includes the intended course with the initial order (eg one end on this grid line, leaving the other end precisely at your ‘STARBOARD TWENTY, ALTERING 340’). coordinate. Do this twice to get both latitude and longitude at ii. The helmsman acknowledges by repeating the order, and the scale on the edge of the chart. reporting when the rudder angle is set (eg ‘TWENTY OF STARBOARD, ON’). 2.2.2 Plotting a position in the chart is done by reversing this method. iii. As the lubbers line passes through a heading 15o before the new course, the helmsman reports to the OOW (eg 2.2.3 Some chart symbols come with a little line and circle ‘PASSING 325’). indicating the precise location, like the “Radio mast”, otherwise iv. The OOW ‘Cons’ the ship on to the new course, and partic- the center of the symbol is the precise location. ularly if large amounts of wheel have been used initially, may first ease the helm (eg ‘EASE TO TEN’) and then when 2.2.4 Another possible notation of 33° 28,5' E is 33° 28′ 30" E, the ship nears its intended course, by ordering ‘MIDSHIPS’. which however doesn't easily allow for more precision like The helmsman responds as described in the above para- 33° 28,500' E does. Also note that in most countries a com- graph. ma - and not a dot - is used as the decimal separator. So v. With the rudder amidships the ship will continue to turn instead of 33° 28.500' E, the consensus notation for mari- and so the OOW will stop the swing by ordering opposite ners is 33° 28,500' E.

wheel (eg ‘PORT TEN’). 2.3 Selection of chart symbols vi. Finally, when on or near the new course, the OOW will or- der ‘MIDSHIPS’, followed immediately by ‘STEER ...’ (eg ‘STEER 340’) or ‘STEADY’. If the OOW gives an order to Danger line in general ‘STEER ...’ then the helmsman applies wheel as required to

do so, but if the order ‘STEADY’ is given, the helmsman is Wreck, least depth unknown but usually to steer the heading shown by the lubbers line at the in- deeper than 20 meters stant ‘STEADY’ was given. Visible wreck c. Alterations of Course up to 10°. When making a small al- Wreck of which the masts only are visible teration of course of up to 10°, the OOW may give a wheel at Chart Datum

order followed by the course required to steer (eg Wreck, least depth known obtained by

‘STARBOARD FIFTEEN, STEER 312’). The helmsman sounding only repeats this, brings the ship to the course ordered using that amount of wheel. When steady on the new course,

the helmsman reports this (eg ‘COURSE 312’).

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5.7 Conning and Control Orders

Wreck, least depth known, swept by wire 5.7.1 Giving Conning Orders drag or diver The term ‘Conning’ means maneuvering the ship by giving wheel, steering or propulsion orders to the helmsman. Other Rock which covers and uncovers, height than the CO, only the Officer of the Watch (OOW) may normally or above Chart Datum give Conning Orders. The helmsman should always acknowledge a Conning order by repeating it before taking action. When a Rock awash at the level of Chart Datum Conning order is not repeated correctly, the OOW should give

the order again, firmly and clearly. If the helmsman is confused Underwater rock of unknown depth, danger- by a wheel order or puts on wheel in the wrong direction, the ous to surface navigation OOW should order ‘MIDSHIPS’ and then give the wheel order Underwater rock of known depth, dangerous again. or to surface navigation 5.7.2 Manual (Hand) Steering Conning Orders Remains of a wreck, or other foul area, non a. Wheel Orders - General. Wheel orders are Conning -dangerous to navigation but to be avoided by vessels anchoring, trawling etc. orders to apply the rudder in a given direction to a particular angle (eg ‘STARBOARD FIFTEEN’, ‘MIDSHIPS’ Depth unknown, but considered to have a etc). The final course intended may be indicated by adding safe clearance to the depth shown ‘ALTERING ...’. An order to steer a course is made by using Sounding of doubtful depth; Existence either the ‘STEER ...’ or the ‘STEADY’ procedure. The term doubtful; Reported, but not confirmed ‘degrees’ is never used. The ‘STEADY’ procedure is Position approximate; Position doubtful useful if only the OOW does not have immediate access to a compass repeat; it is thus not often

used. On receiving a wheel order, the helmsman repeats it

and turns the handlebar (or wheel in some ships) in the required direction to the angle shown on the indicator on the Quartermaster’s console. The helmsman reports when the amount of wheel ordered has been applied, (eg ‘WHEEL IS AMIDSHIPS’ or 'FIFTEEN OF STARBOARD WHEEL, ON’ etc). These principles apply to all

Conning orders.

Symbol & Abbreviations used for wrecks

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a is the radar range between the ship and point A; b is the radar 2.4 Aids to navigation

range between the ship and point B.

a + IE + b + IE = AB 2.4.1 These are special structures like , lightships, , 2 IE = AB - (a + b) buoys, etc that are used to enhance safety by providing more AB - (a + b) opportunities to obtain LOPs. IE = 2

2.4.2 These lights and marks are prescribed across the world by the International Association of Authorities (IALA). In 1977 this IALA endorsed two maritime buoyage systems putting an end to the 30 odd systems existing at that time. Region

A - IALA A covers all of Europe and most of the rest of the world, whereas region B - IALA B covers only the Americas, Japan, the Philippines and Korea. Fortunately, the differences between these two systems are few. The most striking difference is the direction of buoyage.

Fig. 13 Two-mark method 2.4.3 All marks within the IALA system are distinguished by:

5.6 Three-mark method a. Shape b. Colour When three radar-conspicuous and well charted objects are c. Topmark conveniently situated around the ship, radar ranges of all three objects may be taken simultaneously and range arcs from the d. Light objects drawn on the chart, producing a ‘radar cocked hat’, as shown in Fig. 13. The index error equals the radius of the circle 2.4.4 Six types of navigation buoys: drawn tangential to the three range arcs. a. Lateral b. Cardinal c. Isolated danger d. Safe water e. New wreck f. Special

Fig. 14 Three-mark method 55 8

2.4.5 Lateral buoys and marks

2.4.6 The location of lateral buoys defines the borders of channels and indicates the direction. Under IALA A red buoys mark the port

side of the channel when returning from sea, whereas under IALA B green buoys mark the port side of the channel when sailing towards land. Red buoys have even numbers and red lights; green buoys have odd numbers and green lights. Lateral lights can have any calm phase characteristic except FL (2+1).

2.4.7 Generally, when two channels meet, one will be designated the preferred channel (i.e. most important channel). The depict-

ed on the right indicates the preferred channel to starboard Fig. 12 Curves of equal subtended angle under IALA A. The light phase characteristic is R FL (2+1):

5.4.2 Use of the normal chart

If the ship is alongside in a harbor and radar-conspicuous ob- jects are available, then charted and radar ranges of the object may be compared. The difference is the index error.

2.4.8 The buoy depicted on the left indicates the preferred channel to

port under IALA A. These buoys are marked with the names 5.5 Two-mark method and numbers of both channels. The light phase characteristic is G FL (2+1): 5.5.1 The two-mark method may be used if two radar-conspicuous objects are available, the range between them is known accurately from the chart, and the ship is steaming between the marks. Radar ranges of both objects (A and B in Fig. 15-12) are taken simultaneously as the ship crosses the line between them. Both radar ranges include index error (IE). AB is the charted 2.4.9 For an example of lateral buoys used to mark a (preferred) channel, see direction of buoyage below. distance between the two objects;

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2.5 Lateral Marks - direction of buoyage Expected depth and echo sounding. Minimum depths. When fixing and result of fix. EP to next alteration. Maneuvering limits (e.g. 5 cables clear to stbd, 1 cable to port). 2.5.1 Lateral marks are generally for well-defined channels and there f in any doubt, say so and if necessary stop the ship. are two international Buoyage Regions - A and B - where these Lateral marks differ. Where in force, the IALA System applies to 5.3.7 It must be appreciated that, whatever the technique employed, all fixed and floating marks except landfall lights, a drift off line is likely to be detected less readily by radar than and marks, sectored lights and major floating lights. by visual methods.

2.5.2 The standard buoy shapes are cylindrical (can) , conical , 5.3.8 It is vital to pay attention to the echo sounder and the least depth expected. The nearest land is usually the bottom. spherical , pillar and spar , but variations may occur,

for example: minor light-floats . In the illustrations below, 5.4 Radar calibration (Index Error) only the standard buoy shapes are used. In the case of fixed

5.4.1 Radar calibration chart beacons - lit or unlit - only the shape of the top mark is of navigational significance. This is the most accurate method of calculating radar index

error. Charts are produced by the Hydrographic Department, with additional data for certain ports, which enable a ship to fix IALA its position to within 10 yards when at anchor or secured to a Region A buoy. The additional data consist of curves of equal subtended Europe angle between pairs of charted objects (Fig 12). The angles are Africa measured by horizontal sextant and, for example in Fig. 12, a New Zealand Australia sextant angle between A and C of 40° and one between C and B of 50° would fix the ship’s position at point X. The true range of China India a radar-conspicuous mark can therefore be established from the Russia chart and compared with a radar range taken simultaneously Indonesia Turkey with the fix. Any difference is the index error. For example: Middle East Etc. Charted range 1550 yards Radar range 1530 yards Radar index error +20 yards

A correction of +20 yards must be applied to all radar range

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IALA Region B

Americas Philippines Japan Korea

2.6 Cardinal buoys

2.6.1 The four cardinal buoys indicate the safe side of a danger with an approximate bearing. For example, the West cardinal buoy has safe water on its West and the danger on its East side. Fig.11 Blind pilotage: layout of Navigating Officer’s Note Book

2.6.2 Notice the “clockwise” resemblance of the light phase This procedure cuts the time to take a fix and reduces the risk of characteristics. The top marks consist of two black triangles a ‘cocked hat’ due to ship movement. It may be quicker to placed in accordance with the black/yellow scheme of the buoy. interpolate from the range rings rather than use the range

strobe, although the latter will be more accurate. 2.6.3 When a new obstacle (not yet shown on charts) needs to be

marked, two cardinal buoys - for instance a South buoy and an 5.3.5 Ship’s speed. One of the factors affecting the choice of ship’s East buoy - will be used to indicate this “uncharted” danger. The speed will be the rate at which the BPO and his assistant are cardinal system is identical in both the IALA A and IALA B buoy- age systems. capable of dealing with the radar information.

5.3.6 Commentary and conning advice. Maintain a steady, unhurried and precise flow of information to the Command:

Distance off track/on track/course to maintain or regain. Distance and time to next ‘wheel over’, new course. Present/new course clear of shipping. Adjacent marks or hazards, expected lights and sound signals.

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Fig. 10 Blind pilotage: preparation of the chart and displays

Cardinal Marks 5.3 Blind Pilotage Execution

5.3.1 Carry out a time check to synchronies clocks and watches. 2.7 Marks indicating isolated dangers

5.3.2 On the radar display, keep one set of parallel index lines drawn 2.7.1 This type of buoy indicates the position of an isolated danger, up ahead of those in use. Any more will clutter the display contrary to cardinal buoys which indicate a direction away from excessively. Rub out lines as soon as they are finished with. the danger.

5.3.3 Identify contacts early (by range and bearing from charted 2.7.2 Body: black with red horizontal band(s); Topmark: 2 black spheres. The light (when present) consists of a white flash: Fl(2). object). An accurate EP is a most useful aid in identification.

5.3.4 Fix at frequent intervals and immediately after a change of course. DR/EP ahead. A suitable fixing procedure is:

BPO assistant ‘Stand by fix in 1 minute’ BPO ‘Roger using points A, B, C’ BPO assistant writes these in Note Book. 2.8 Marks indicating safe water BPO/BPO assistant ‘Fix now.’ BPO marks the point on face of the display. BPO assistant notes the time. 2.8.1 This type of buoy indicates the position of an isolated danger, BPO then ranges off the marks drawn on display and passes contrary to cardinal buoys which indicate a direction away from these to BPO assistant. the danger. BPO assistant Records the ranges, plots the fix and generates fresh DR and EP.

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2.8.2 Body: red and white vertical stripes; Topmark (if any): single red sphere. Lights are typically calm and white: Morse A, Iso, Occ or LFl 10s.

2.9 Marks for new wrecks

2.9.1 After the sinking of the “Tricolor” in the Pas de Calais (Dover Straits) in 2002, several other vessels hit the wreck despite standard radio warnings, three guard ships and a lighted buoy.

2.9.2 This incident spawned a new type of buoy, the emergency Blind pilotage symbols wreck marking buoy, which is placed as close as possible to a new dangerous wreck. 5.2.11 The Note Book should contain the full plan, neatly and legibly 2.9.3 The emergency wreck marking buoy will remain in position until: recorded in chronological order. Sketches of both chart and radar

display (Fig. 10) can be of great assistance to the BPO in a) The wreck is well known and has been promulgated in nautical publications; evaluating the picture. A suitable Note Book layout b) The wreck has been fully surveyed and exact details such as supplementing Fig. 10 is shown in Fig. 11 as a guide to blind position and least depth above the wreck are known; and pilotage planning. c) A permanent form of marking of the wreck has been carried out. 5.2.12 Tracks plotted for entering and leaving harbor should not appear

on the same chart simultaneously, otherwise confusion will arise.

5.2.13 Clearing range should be simple, safe and easily interpreted.

5.2.14 Objects used for ‘wheel over's’ should be conspicuous, easily identifiable and suitably located adjacent to the track.

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5.2.7 Expected soundings (allowing for height of tide and calibration 2.9.4 The buoy has the following characteristics: of echo sounder) should be noted for each leg. The possibility of being early or late should also be borne in mind. a. A pillar or spar buoy, with size dependant on location. 5.2.8 All hazards along the track should be boxed in by clearing b. Colored in equal number and dimensions of blue and yel- ranges and their cross-index ranges listed in the Note Book. low vertical stripes (minimum of 4 stripes and maximum of

8 stripes). 5.2.9 Details of all lights and fog signals should be taken from the Admiralty List of Lights/chart and entered in the Note Book. c. Fitted with an alternating blue and yellow flashing light with

a nominal range of 4 nautical miles where the blue and 5.2.10 The chart should be drawn up using standard symbols. yellow 1 second flashes are alternated with an interval of Blind pilotage chartwork Symbol 0.5 seconds. B1.0s + 0.5s + Y1.0s + 0.5s =

Parallel index lines to stay on 3.0s track d. If multiple buoys are deployed then the lights will be Clearing ranges ‘Wheel over’ (WO) ranges synchronized. e. A racon Morse Code “D” and/or AIS transponder can be Blind pilotage symbols used. f. The top mark, if fitted, is a standing/upright yellow cross Use the same conventions as above for cross-index ranges. The term dead range is used to describe the range of a mark . ahead when anchoring in a chosen position. The term may 2.9.5 It is important to realize - especially for the colour-blind - that also be used when measuring the progress of a radar- this new buoy breaches the useful and crucial convention: vertical conspicuous object along a parallel line. stripes equal safety, horizontal stripes equal danger.

2.10 Special buoys and marks

2.10.1 have saved these buoys for last since they lack an actual navigational goal. Most of the time these yellow buoys indi- cate pipelines or areas used for special purposes.

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5.2 Blind Pilotage Planning 2.10.2 have drawn the five official IALA shapes, from left to right:

conical, spar, cylindrical, pillar and spherical. 5.2.1 Normal planning considerations for selection of tracks apply. Blind and visual tracks should be the same, to enable the transition 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.

5.2.2 The number of course alterations should be kept to a minimum to 2.11 Chart symbols reduce the work load in redrawing parallel and ‘wheel over’ lines.

2.11.1 The seafaring nations of the world - members of the 5.2.3 Always try to have two parallel index lines _ where possible, one International Hydrographic Organization - agreed in 1982 on an universal set of chart symbols, abbreviations, colours, etc to be on each side of the track. These provide a check on measurement, mark identification and can reveal index or used in the , in order to obtain uniformity. On reg- linearity errors. ular charts a white, red, yellow or green lights will be indi-

cated by , and on GPS displays and modern multi-coloured 5.2.4 Objects to be used both for parallel index lines and for fixing charts in specific colours: , with the yellow coloured lobe must be carefully selected. They should be radar-conspicuous and indicating a white light. The precise position of a chart symbol is unchanged by varying heights of tide. Clearly mark on the chart its center, or is indicated with a line and circle , the “position the objects to be used for fixing and brief the assistant. Avoid if circle”. possible fixing by radar range and bearing on a single mark.

2.12 Two distinct types of sea mark are drawn differently in 5.2.5 The range scales to be used require careful consideration. the chart: Accuracy is greater at shorter ranges but marks pass more quickly than at a distance, requiring more lines to be drawn. 2.12.1 beacons - fixed to the seabed; drawn upright; When operating on short-range scales, it is essential that the BPO

frequently switches to longer ranges to keep aware of developing 2.12.2 Buoys - consisting of a floating object that is usually anchored to situations. Changes of range scales and parallel index marks a specific location on the sea floor; drawn at an oblique angle should be pre-planned and marked in the Note Book. The stage and with oblique numbering, descriptions of colours and light at which charts will be changed must also be carefully characteristics. considered.

5.2.6 Tidal streams and currents should be worked out and noted for calculation of courses to steer and for the calculation of EP. These should be displayed on the chart and recorded in the Note Book.

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Major floating light (light-vessel, major light- CHAPTER 5 float, LANBY) BLIND PILOTAGE Light-vessel

5.1 Introduction Major light; minor light

Blind pilotage means the navigation of the ship through restrict-

ed waters in low visibility with little or no recourse to the visual Green or black buoys (symbols filled black): G observation of objects outside the ship. The principal non-visual = Green ; B = Black aid to navigation that enables this to be done is high-definition warning-surface radar, but all available non visual aids are em- Green or black (symbol filled black). ployed. The organization to achieve this is called the blind pilot- Note the upright G, instead of an oblique G

age organization, comprising a BP team, led by a BP Officer (BPO). Single coloured buoys other than green and

black: Y = Yellow ; R = Red

Coloured beacon other than green and black, the symbol is again filled black so only the shape of the topmark is of navigational significance.

Multiple colours in horizontal bands, the

colour sequence is from top to bottom

Multiple colours in vertical or diagonal stripes, the darker colour is given first. W = White

Spar buoy (here a safe water mark)

Lighted marks on multi-coloured charts, GPS

displays and chart plotters.

Lighted red beacon on standard charts.

Red beacon and green buoy with topmark, colour, radar reflector and designation. Clearing and ‘wheel over’ ranges on the chart and the radar display Red buoys and marks are given even numbers, green buoys and marks are given odd numbers.

47 16

Wave-actuated bell buoy to the left, and to the 4.7.7 The likelihood of dragging is dependent on: bad weather; right a Light buoy, with a horn giving a single blast whether the anchorage is open or sheltered; the strength and every 15 seconds, in conjunction with a wave -actuated whistle. Other sounds include “Gong”, direction of the tidal stream; the nature of the bottom; the

“Siren”, “Diaphone” (Dia). holding power of the anchor. The ship is usually moving very The fog signal symbol may be omitted when a slowly at the time of ordering the anchor to be let go, so the description of the signal is given. time for the anchor to reach the bottom may normally be disre- garded.* Leading beacons - Leading line (firm line is the track to be followed) 4.7.8 Rigid application of these considerations would preclude some

anchorages which would be quite safe in good weather or in Leading lights (≠ : any two objects in line under each other). Bearing given in degrees and sheltered conditions or of a short duration. In such circum- minutes. The lights are synchronized. The red light stances, it would be appropriate to accept a smaller margin of has a shorter nominal range (the distance from safety, consistent with prudence. which the light can be seen): 10 nautical miles.

4.7.9 Suppose a ship of draught 7.1 m, length 155 m, with 10 shack- All-round light with obscured sector les (275 m) of usable cable on each anchor, comes to single an-

chor. The minimum height of tide during the stay is predicted at 1.7 m. Assuming that the safety margin is 1½ cables, her safety on multi-coloured charts. swinging circle (SSC) would be as in Table 14-1. The elevation is 21 metres (height of the light structure above chart datum). The nominal range of the white light is 18 nautical METRES YARDS miles. The range of the green and red light is 12 Length of ship 155 170 nautical miles. Maximum usable 275 300 cable Main light visible all-round with red subsidiary light Safety margin 275 300 seen over danger. The fixed red light has an ______Radius of SSC 705 770 or 3.85 elevation of 55 metres and a nominal range of 12 nautical miles. The flashing light is white, with cables three flashes in a period of 10 seconds. The elevation is higher than the red light: 62 metres and the range of the white light is 25 nautical miles. Table 14-1 Symbol showing direction of buoyage (where not obvious) 4.7.10 Thus, her berth must be at least 3.85 cables from the LDL. The charted depth of the LDL would be 7.1 + 2 - 1.7 = 7.4 m, allow- ing for a minimum clearance of 2 m under the keel. Symbol showing direction of buoyage (where not obvious), on multi-coloured charts (red and green circles coloured as appropriate), here IALA A

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2.12.3 Fulll example of a light description in the chart: 4.7.5 Proximity of dangers

Fl(3)WRG.15s21m15-11M To be safe from rocks shoals, etc., an anchorage position must be chosen so that the safety swinging circle (Fig. 9) is clear of the LDL. The radius of this circle may be obtained by adding the Class of light: group flashing repeating a group of three following. flashes; Colours: white, red, green, exhibiting the different colours in a. The length of the ship. defined sectors; Period: the time taken to exhibit one full sequence of 3 b. The maximum amount of cable which can be veered on flashes and eclipses: 15 seconds; the selected anchor (remember that the last shackle of Elevation of light : 21 metres; cable will normally be inboard of the hawse pipe). This Nominal range(s): white 15 M, green 11 M, red between 15 allows for the veering of additional cable should the weath- and 11 M, where “M” stands for nautical miles. er deteriorate, while still maintaining an adequate safety

margin. c. A safety margin. It is impossible to give any definite rule as to how near danger a ship may be anchored in safety. An ample safety margin must be allowed, in addition to (1) and (2) above. At single anchor, it is usual to allow at least one cable (1/10 mile), increased as necessary, to allow for:

i. The possibility that the ship may not achieve her intended anchoring position. ii. The likelihood of bad weather. iii. The likelihood of dragging. iv. The time between ordering the anchor to be let go and it hitting the bottom.

4.7.6 Anchoring by day in perfect visibility using a large-scale chart, in a flat calm with a conspicuous head mark and beam marks, should not present any great difficulty even to the inexperienced navigator. The possibility that the ship may not achieve her in- tended position is slight. But achieving the planned anchorage

position in a minutely charted bay, at night, in a gale, with diffi- cult marks when the final run-in is only 1 or 2 cables, is an en- tirely different matter.

45 18

CHAPTER 3 d. For the heavier aluminum bronze cable, which requires less cable for the depth of water, the approximate rule is: CHARTWORK

Amount of cable required 3.1 Position Lines (in shackles) = √depth (in meters)

OR = √1.3 depth (in fathoms) 3.1.1 Any line drawn on the chart on which the position of the ship is

known to lie.

Visual Bearing 4.7.4 Safety Swinging Circle

Astronomical Observation A ship at anchor must have room to swing clear of dangers such Range (Radar or Vertical Sextant Angle) as shoal water, rocks, etc. and also to swing clear of adjacent ships at anchor that are themselves swinging round in their berths.

3.2 Fixing

3.2.1 The intersection of two or more position lines, which have been obtained at the same time, will give the position ship.

Visual Fix (Arrows away from object and 0915 four digit time)

Range Fix (Arrows on both ends and four 1015 digit time)

Fig. 9 Safety swinging circle Radio Aid Fixes (D) – Decca Suffixes 0845 should be inserted where ambiguity exists

(O) – Omega (L) – Loran

(M) – MFDF (S) - Satnav

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4.7.3 Choosing a position in which to anchor 3.3 Chart work Planning symbols

a. A number of factors have to be considered when choosing a position in which to anchor. The choice is governed very largely by matters of safety, but administrative or operational reasons may also have to be taken into account.

b. These factors are:

i. The depth of water ii. The length and draught of the ship. iii. The amount of cable available. iv. The type of holding ground. v. The proximity of dangers such as shoal waters, rocks, etc. vi. The proximity of adjacent ships at anchor. vii. The shelter from the weather given by the surrounding land. viii. The strength and direction of the prevailing wind. ix. The strength and direction of the tidal stream. x. The rise and fall of the tide. xi. The proximity of landing places.

c. The amount of forged steel cable required for various depths may be calculated by the following rule, which allows a slight safety margin over the actual minimum necessary:

Amount of cable required (in shackles) = 1½ √depth (in meters) OR = 2 √depth (in fathoms)

43 20

3.4 Example for Coastal Navigation 4.7.2 Types of seabed

Thick mud, clay and sand will provide good holding, as will pebbles once the anchor is deep enough. A rocky seabed

might perhaps provide even better holding, but also increases the risk of a permanent mooring when the chain or anchor it- self gets jammed under a heavy boulder. Therefore, especially when dealing with rocks, the use of a trip line or tripping

line is recommended to enable you to retrieve your anchor.

Thick layers of shells are rather useless: at least with seaweed and grass the anchor has a chance to penetrate into the more suitable layers underneath.

S Sand

M Mud

Cy, Cl Clay G Gravel

Co Coral

Cb Cobbles

Sn Shingle

P Pebbles

St Stones

Rk, Rky Rock, Rocky

Ch Chalk

Sh Shells

Wd Weed

S/M Two layers (example: sand over mud)

Kelp

Spring in seabed

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c. Moreover, the seabed might even be unusable for 3.5 Dead Reckoning (D.R): anchoring, as is the case with cables, telephone lines or pipelines, which will be indicated on the nautical chart as 3.5.1 This is the position of the ship found by allowing for the illustrated below. courses steered and distance steamed through the water from a Fixed Position or any starting position without taking into consideration the effect of wind, current etc.

3.5.2 It is only an approximate position. Time is indicated using two digits.

Course steered d. Other reasons why anchoring may be forbidden are an (Distance in 15 mins) explosives dump area or a historic wreck, or simply because 090 anchoring will block the passage. Also the seabed might be

foul, which is indicated on nautical charts by a #, marking 1300 15 30 45 1400 perhaps old chains or simply polluted ground below. 10 Speed Likewise you should avoid naval (submarine) exercise are- 2.5nm as, nature reserves, precious coral and areas with divers down).

3.6 Clearing bearings

3.6.1 Once the track has been decided upon, clearing bearings should be drawn on the chart clear of the limiting danger line. These clearing bearings define the area of water in which it is safe to navigate.

3.6.2 The clearing bearing needs to be displaced from the LDL to such an extent that the ends of the ship (usually the bow or

stern) will still be in safe water if the bridge is on the

clearing bearing. But this distance should not be so great that the clearing bearing is disregarded when approached.

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4.6.3 Tide levels and heights

Displacement of the clearing bearing from the LDL

3.6.3 No hard and fast rule for the distance of the clearing bearing from the LDL can be laid down. It depends on the width of safe navigable water, the angle between the intended track and the

LDL, the weather and tidal stream and the safety margin already allowed for in the LDL. In the figure above a fairly narrow chan- nel where the track is parallel to the LDL a clearing line displaced by a distance equal to ¼ of the distance between the bridge and the stern should be sufficient to keep the ship clear of danger, provided that any alteration of course away from the clearing

bearing is not too great.

3.6.4 It shows the ship altering course away from shoal water at angel of about 15° to the LDL, with the bridge on the clearing bearing. Tide Level and Heights In such circumstances the stern is right on the LDL, so the only further safety factor ‘in hand’ is the additional depth margin built in to the LDL. If there is plenty of room available, the distance of 4.7 Anchorage the clearing bearing from the LDL may be as much as the full distance between the bridge and the stern. This permits a 90° 4.7.1 The seabed - where to anchor alteration of course away from the LDL yet still allows the stern to a. Since a good anchor digs itself into the seabed we're be in a safe depth. Interested in more than just the upper layer. Shells, weed

and sea grasses might prevent an anchor from grabbing.

But once through, the anchor can dig itself into the lower sandy, mud, peat, cobbles, stony or clay bottom, each with different holding characteristics, requiring different anchor types. b. Mud, for instance will provide better holding than peat -

which is often too watery - yet usually we cannot pick the

seabed.

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4.6 Chart datum and land survey datum CHAPTER 4

THE PILOTAGE PLAN 4.6.1 To determine how tidal levels vary along any given stretch of

coastline, all levels must be referred to a common horizontal 4.1 Introduction plane. Chart datum is not a suitable reference because it is

dependent on the range of the tide. In Great Britain, the 4.1.1 The pilotage plan must be complete in every detail. Pre-planned Ordnance Datum at Newlyn may be regarded as a suitable hori- data are essential for a passage in confined waters. The track zontal plane and should be used if comparisons of absolute must be drawn on the chart, using head marks, if possible. The height are required. On large- and medium-scale charts for which position along the track must be instantaneously available from the Hydrographer is the primary authority, the panel giving tidal height may also tabulate the difference between chart and cross bearings.

ordnance datums for the area. Other countries have their own land survey datums; some of these are listed in Table IV of 4.1.2 The safe limits each side of the track must be defined by clearing Volume 1 of the Tide Tables. bearings. With appropriate details transcribed into a properly prepared Note Book, the Navigating Officer can give his whole attention to the conning and safety of the ship without having to 4.6.2 If absolute heights are required at a point on the coast where no consult the chart. Reports from the navigator’s assistant, the tidal data are given, or where there is no connection to land survey datum, they should be obtained by interpolation from echo sounder operator, the blind (safety) and/or visual fixing teams, serve to confirm (or deny) the accuracy of the navigation. heights obtained from places on either side where data is

available. 4.1.3 If time has to be spent poring over the charts and publications during pilotage instead of conning the ship, it will be evident

either that the plan has not been fully prepared, or that the

Navigating Officer does not have confidence in it. The plan must be so organized that, at each stage, the Navigating Officer recognizes those factors demanding his attention with sufficient time to deal with them.

4.1.4 For example, the plan will need to include the selection of ‘wheel

over’ points and the observation of transits to determine the gyro

error. Neither of these operations should interfere with the other. These points concern the execution of the plan rather than the planning, but consideration of such details at the planning stage will ensure a sounder plan, simpler to execute.

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4.2 Selection of the track 4.5.2 Tide calculation for Primary Port and Secondary Port

4.2.1 Read the Sailing Directions and the Port Guide for advice on 16 JANUARY (Friday) selecting the track. The track should normally be to the starboard side of the channel as laid down in The International Regulations KEDAH PIER (PENANG) 0324 0.9 for Preventing Collisions at Sea, 1972(the Rule of the Road). This 1014 1.8 1514 1.3 allows vessels coming in the opposite direction to pass in safety. 2127 2.2 If the ship is large relative to the size of the channel, it may be necessary to plan to use the center line, in which case one of the Example 1: To find the times and heights of high and low waters th following possibilities may arise: at Secondary Port on 16 January using the following extracts:

a. The ship may have to move to the starboard side of the Extracts from Part II channel to allow room for other ships to pass. b. Other vessels may have to be instructed by the Port Authority to keep clear. Place Position Times Height Difference (in meters) Difference c. Special regulations may be in force for ‘vessels constrained (MHW) (MLW) ((MHWS) (MHWN) (MLHWN) (MLWS) Kedah Pier (Lat) | (Long) by their draught’ as defined in the Rule of the Road. Such (Standard (See Extract) special regulations usually only apply to the larger ships; (of Port) 2.5 1.8 1.2 0.4 the order of: draught 10 to 10½ metres or more; length Tanjung (North) (East) 270 metres or more; deadweight 100,000 tonnages or Dawai 05˚ 40’ 100˚ (Secondary 21’ -0021 -0021 +0.1 +0.1 0.0 0.0 more). Details of the regulations governing (2) and (3) Port) above are usually to be found in the Sailing Directions.

4.2.2 Dangers H.W H.W L.W L.W Make sure the track chosen passes clear of dangers, and that the Predicted times at Kedah Pier 1014 2127 0324 1514 ship does not pass unnecessarily close to them. Dangers should already Time Differences at Tanjung Dawai -0021 -0021 -0021 -0021 have been highlighted by the LDL. If the tidal stream is predicted to set Predicted Times at Tanjung Dawai 0953 2106 0303 1453 the ship towards a danger, it is usually advisable to allow an in- creased margin of safety. H.W H.W L.W L.W

Predicted height at Kedah Pier 1.8 2.2 0.9 1.3 Interpolated

height difference at Tanjung Dawai +0.1 +0.1 0.0 0.0 Predicted height at Tanjung Dawai 1.9 2.3 0.9 1.3

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d. By reciprocal bearings with another ship of known 4.2.3 Tidal streams and wind

compass error. a. If the tidal streams across the track are likely to be large,

the courses to steer to counter them should be decided e. By reduction of the cocked hat. If it seems certain that the beforehand. cocked hat is due to compass error alone and none of the b. A rule of thumb for this is: above four methods are available to resolve it, then the At speeds of 10 to 12 knots, allow 5° for each knot of tidal cocked hat may be reduced and the error found, as stream across the course. At a speed of 5 knots, allow 10°. follows. Assume the error has a definite sign (+) or (-) and This rule is correct to within about 1° of the course steered is the same for each bearing. † Although the actual for tidal streams up to 3 knots across the track. Leeway bearings may be incorrect, the true angles between the objects are known. Two angles may be obtained from caused by wind must also be considered. This information should be available in the Navigational Data Book. A rough three objects. These angles may then be set on a station rule for a frigate at slow speed is that 20 knots of wind is pointer or drawn on a Douglas protractor (both about equivalent to 1 knot of tidal stream. When the depth instruments are described in Volume III) and the position of water under the keel is restricted, leeway will be found by rotating the instrument until the arms or lines go considerably reduced and this fact may often be used to through the charted position of each object. The bearing advantage. of the furthest object may then be taken from the chart and compared with the observed bearing, the difference being the error in the compass. 4.2.4 Distance to run

a. To assist in arriving on time, distances to run should be marked on the chart from the berth or anchorage. 4.5 Tide Distances to run should be marked at every mile over the last few miles and every cable in the last mile to anchorage 4.5.1 The tide is the vertical rise and fall of the sea level surface or berth. This will assist in planning when to order reduc- caused primarily by the change in gravitational attraction of the tions in speed. moon, and to a lesser extent the sun. b. The times at which it is required to pass through positions to achieve the ETA at the planned pilotage speed should be marked on the chart at appropriate intervals.

37 26

4.2.5 Night entry/departure a. By a transit. The compass bearing of two charted objects is

observed when they are in line and the true or magnetic If possible, the tracks chosen should be such that they can bearing obtained from the chart. The difference between equally well be run by night as by day. them will be the gyro error or deviation of the gyro or

magnetic compass respectively. For example: 4.2.6 Blind pilotage

Charted transit 079° Consider the action to be taken in the event of restricted vis- Gyro compass bearing 081° ibility. The plan should be equally safe for blind pilotage as for Gyro error 2° high visual conditions. The track selected should enable the change -over from visual to blind and vice versa to be made at any Charted transit (magnetic) 123° Magnetic compass bearing 120° time. Radar can frequently be used to support the visual plan. Deviation (CADET) 3° east (Error East Compass This is common practice in merchant ships and warships where Least) the pilotage team is small in numbers. b. By azimuth of a heavenly body. The error of the compass 4.2.7 Constrictions may be found by comparing the observed bearing of a heavenly body with that calculated. Details of the If the track has to pass through a constriction (for example, a procedure are given on Weir’s azimuth diagram (to be narrow section of a channel) plan to steady on the requisite found in the Miscellaneous Chart Folio 317) and in Norie’s course in plenty of time. This is most important if there is any Tables (ABC Tables or Amplitudes and Corrections), and strong tidal stream (or wind) across the track. Furthermore, also covered in the revised edition Volume II of the Admi- this precaution gives time to adjust to the planned track on the ralty Manual of Navigation. The Amplitudes Table (and correct heading should the ship fail to achieve this immediately Corrections) for the rising and setting heavenly body is the on altering course. most accurate procedure of the three. The HP-41CV calculator, outfit PDQ, may also be used to calculate the 4.2.8 The Sun true bearing of a heavenly body using the Sight Reduction Table (SRT) sub-routine. Work out the bearing and altitude of the Sun likely to be

experienced as dazzle during the passage. Try to avoid tracks c. By bearing of a distant object. The ship may be fixed by and ‘wheel over’ bearings which look directly up Sun, horizontal angles, or may be in a known geographical especially at low elevations, when it may be difficult to pick up position, e.g. South Railway Jetty, Portsmouth Dockyard. the requisite marks. An observed compass bearing of a distant object* may then be compared with the bearing taken from the chart and the error deduced.

27 36

4.3 Execution of Pilotage 4.2.9 Head marks

Suitable head marks should be selected for the chosen tracks. 4.3.1 The essence of a good plan is knowing the limits within which the Transits are best but, if these are not available from the chart, ship may be navigated in safety. The essential questions which a conspicuous object should be used instead. Choose an object the Navigating Officer must be able to answer at all times during a such as a lighthouse, pier, fort, etc. Which is unlikely to be pilotage passage are: confused with anything else. Chimneys, flagstaffs, radio masts

and even churches can cause confusion if there are a number a. Is the ship on track? in close vicinity. Flagstaffs are frequently removed or b. If not, where is the ship in relation to the track and what repositioned; chimneys and radio masts can change without steps are being taken to regain it? notification. Avoid choosing objects which may no longer be c. How close is the ship to danger? visible because of changing topography. d. How far is it to the next alteration of course? e. Are the tidal streams and depths of water as predicted? 4.2.10 Transits

4.4 Error in the Compass and Eliminating the Cocked Hat Many harbour plans show two marks which, when kept in line, lead the ship clear of dangers or along the best channel. Such 4.4.1 If it seems certain that the cocked hat is caused by compass error marks are called leading marks and are often shown on a chart alone, then the error must be determined and a correction applied by a line drawn from them, called a leading line (Fig. 5,). The to the plotted bearing. In the first instance, check that any known leading line is usually shown as a full line (CD in Fig. 5) where error has been correctly applied. it is safe to use the marks, and dotted elsewhere. The names of the objects and the true bearing from seaward, are usually 4.4.2 A gyro error high must be subtracted from, and a gyro error low written alongside the line (see Chart Booklet 5011, Symbols added to, the gyro bearing. Variation and deviation westerly and Abbreviations Used on Admiralty Charts). If the two must be subtracted from, and variation and deviation easterly objects chosen are seen to remain in transit (Fig. 5a), the ship added to, the magnetic compass bearing. must be following the selected track, BD in Fig. 5. If the two objects are not in line (Fig. 5b) the ship must be off track to 4.4.3 The deviation to be applied must be for the compass course and one side or the other. In Fig 5b), the marks are open, with the not the compass bearing. This is a frequent cause of error in the monument open right of the beacon. This means that the plotted bearings using a magnetic compass. The error in the gyro observer is on or in the close vicinity of track BE in Fig. 5. compass and the deviation in the magnetic compass may be checked by any of the following methods:

35 28

Fig. 5 Leading marks, leading line

Fig. 5a Using a transit: objects in transit

Fig. 5b Using a transit: monument open right of beacon Pilotage plan for a ship entering harbor_the Note Book layout

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4.2.11 Line of bearing

a. If no transit is available, a line of bearing should be used instead (Fig. 6).

Fig. 6 Line of bearing

b. The track is drawn on the chart to pass through some well defined object ahead of the ship and the bearing of this line noted. Provided the bearing of the object remains on the bearing noted, the ship must be on her track. If the bearing

changes, the ship will have been set off the track, and an

alteration of course will be necessary to regain the line of bearing.

4.2.12 Edge of land

Edges of land such as cliffs can be useful head marks, particularly

if they are vertical or nearly so. If the edge of land is sloping (Fig

7) the charted edge is the high water mark and it is this which should be used.

Example of Pilotage plan for a ship entering harbour the Note Book sketch

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4.2.14 Keeping the record

A complete record, showing navigational information in sufficient detail for the track of the ship at any time to be reconstructed

accurately, is to be kept in the Navigational Record Book. An example is given in Fig. 8. The following symbols may be employed:

left-hand edge (of land, etc.)

Using the edge of land as a head mark Fig. 7 right-hand edge (of land, etc.)

Port (5c) abeam to port (5 cables)

4.2.13 No head mark available Stbd (1'.2) abeam to starboard (1.2 miles)

If no head mark is available, a mark astern is preferable to none at all but, if no marks are available, the alternatives are:

a. Fix and Run. Plan to fix the ship’s position as accurately as

possible by bearings (taking into account any gyro error) to confirm the safety of the course. Any suitable object* on the bearing of the new track should be observed and used as a head mark when steady on the new course.

b. A bearing lattice. This is easy to prepare and can be transcribed to a Note Book. Two bearings taken at the same time by the Navigating Officer at the pylorus will

immediately tell him whether the ship is off track and, if so, by how much.

c. A HSA lattice. This is very accurate but takes time to

prepare and requires a fixing team of about three people

independent of the Navigating Officer.

Fig. 8 The Navigational Record Book 31 32