terrestrial navigation 1 The topographic surface is the actual surface of the Earth, upon which geodetic measurements are made. These measurements are then reduced to the geoid. Marine navigation measurements are made on the ocean surface which approximates the geoid. The geoid is a surface along which gravity is always equal and to which the direction of gravity is always perpendicular. The latter point is particularly significant because optical instruments containing leveling devices are commonly used to make geodetic measurements. When properly adjusted, the vertical axis of the instrument coincides exactly with the direction of gravity and is by definition perpendicular to the geoid. See Figure 1.1. The geoid is that surface to which the oceans would conform over the entire Earth if free to adjust to the combined effect of the Earth’s mass attraction and the centrifugal force of the Earth’s rotation. Uneven distribution of the Earth’s mass makes the geoidal surface irregular. The geoid refers to the actual size and shape of the Earth, but such an irregular surface has serious limitations as a mathematical Earth model because:
Contents Chapter FUNDAMENTALS 1.1 The shape and dimensions of the Earth 1.1.1 The Shape of the Earth 1.1.2 The Ellipsoid 1.2 Coordinates of the earth 1.2.1 Major point, line and plane on the earth 1.2.2 Coordinates on the earth 1.2.3 Relationship between coordinates 13 1.3 Principal radii of curvature at a point on an ellipsoid 14 1.3.1 Radius of curvature of the parallel 14 1.3.2 Meridian radius of curvature 16 1.4 Datums 19 1.4.1 Definitions 19 1.4.2 Development of the World Geodetic System 20 1.4.3 Datum Shift 21 1.5 Popular nautical measuring units 25 1.5.1 Length along the graticule of the ellipsoid 25 1.5.2 The nautical mile 26 1.5.3 Some popular nautical measuring units 27 1.6 Difference of latitude and longitude 28 1.6.1 Latitude difference 28 1.6.2 Longitude Difference 28 1.7 Visibility at sea 29 1.7.1 Concept of visibility 29 1.7.3 Distance between objects above horizon 32 Chapter NAUTICAL CHARTS 35 2.1 Charts fundamentals 35 2.1.1 Definitions 35 2.1.2 Chart scale 35 2.1.3 Distortion of Ellipse in projections 37 i 2.2 Classification of map projections 40 2.3 Chart Projections 44 2.3.1 Definitions 44 2.3.2 Selecting a Projection 45 2.3.3 Types of Projections 46 2.4 States the requirements of a chart appropriate for marine navigation 60 2.4.1 Charts drawn on the Mercator projection 60 2.4.2 Charts drawn on the gnomonic projection 61 2.5 Mercator Projection/Chart 62 2.5.1 Principle of the Mercator projection 62 2.5.2 Small element geometry 63 2.6 Measuring distance on nautical chart 67 2.7 Transverse Mercator Projection 68 2.8 Gnomonic Projection 69 Chapter DETERMINING THE DIRECTIONS AND BEARINGS AT SEA72 3.1 The principle of determining the directions and bearing at sea 72 3.1.1 The plane of true horizon 72 3.1.2 Identify four major directions 72 3.2 Determining the bearing of a target at sea 73 3.2.1 Definition 73 3.2.2 Bearing measurement 73 3.2.3 Classification of Bearings 74 3.3 Earth's magnetic field and magnetic compass deviation 77 3.3.1 Earth's magnetic field 77 3.3.2 Earth’s magnetic variation 78 3.3.3 Ship’s Magnetism 80 3.3.4 Deviation 81 3.4 Determining Course at sea 81 3.4.1 Course, track, route and heading 81 3.4.2 Relationship between true and magnetic direction 82 3.4.3 Relationship between course and heading 83 Chapter CHARTS - CHART WORK 84 ii 4.1 Paper chart 84 4.1.1 Chart Classification 84 4.1.2 Informations on the chart 87 4.1.3 Chart Accuracy 89 4.1.4 International Charts 91 4.1.5 Using, stowing and Maintaining Charts 92 4.1.6 Charts and Nautical Publication Corrections 94 4.1.7 How to apply the updates to your charts 108 4.1.8 Chart Reading 121 4.2 Electronic Chart Display Information System-ECDIS 130 4.2.1 The Importance of Electronic Charts 130 4.2.2 Classification of ECDIS chart 131 4.2.3 Components of ECS’s and ECDIS’s 133 4.2.4 ECDIS Performance Standards 134 4.2.5 Display Characteristics 135 4.2.6 Units, Data Layers and Calculations 138 4.2.7 ECDIS Outputs 138 4.2.8 Correcting electronic charts 139 4.2.9 Digital Chart Accuracy 142 Chapter IALA MARITIME BUOYAGE SYSTEM 144 5.1 Outline of IALA maritime buoyage system 144 5.2 Types of marks 145 5.2.1 Marks 145 5.2.2 Characteristics of Marks 146 5.2.3 Colors of Marks 146 5.2.4 Shapes of Marks 146 5.2.5 Topmarks 147 5.2.6 Colors of Lights 147 5.2.7 Phase Characteristics of Lights 147 5.3 Details of Marks 147 5.3.1 IALA Lateral Marks 147 5.3.2 IALA Cardinal Marks 151 iii 5.3.3 IALA Isolated Danger Marks 153 5.3.4 IALA Safe Water Marks 154 5.3.5 IALA Special Marks 155 5.3.6 IALA New Dangers 156 5.4 Chart Symbols and Abbreviations of Marks 157 5.5 Sound signals 158 5.5.1 Types of Sound Signals 158 5.5.2 Limitations of Sound Signals 158 Chapter NAUTICAL PUBLICATIONS 161 6.1 General introduction 161 6.2 Details of Nautical Publications 162 6.2.1 List of Lights and Fog Signals (ALL) 162 6.2.2 Sailing Direction 176 6.2.3 Admiralty Tidal Stream Atlas 181 6.2.4 Annual summary Notice to Mariners 185 6.2.5 Notices to Mariners (NMs) 187 6.2.6 Cumulative Notices to Mariners 188 6.2.7 Admiralty tide Tables (NP 201-208) 189 6.2.8 The Mariners Handbook (NP100) 189 6.2.9 The Admiralty List of Radio Signals 190 iv Chapter FUNDAMENTALS 1.1 The shape and dimensions of the ship 1.1.1 The Shape of the Earth The topographic surface is the actual surface of the Earth, upon which geodetic measurements are made These measurements are then reduced to the geoid Marine navigation measurements are made on the ocean surface which approximates the geoid The geoid is a surface along which gravity is always equal and to which the direction of gravity is always perpendicular The latter point is particularly significant because optical instruments containing leveling devices are commonly used to make geodetic measurements When properly adjusted, the vertical axis of the instrument coincides exactly with the direction of gravity and is by definition perpendicular to the geoid See Figure 1.1 The geoid is that surface to which the oceans would conform over the entire Earth if free to adjust to the combined effect of the Earth’s mass attraction and the centrifugal force of the Earth’s rotation Uneven distribution of the Earth’s mass makes the geoidal surface irregular The geoid refers to the actual size and shape of the Earth, but such an irregular surface has serious limitations as a mathematical Earth model because: •It has no complete mathematical expression; •Small variations in surface shape over time introduce small errors in measurement •The irregularity of the surface would necessitate a prohibitive amount of computations The surface of the geoid, with some exceptions, tends to rise under mountains and to dip above ocean basins For geodetic, mapping, and charting purposes, it is necessary to use a regular or geometric shape which closely approximates the shape of the geoid either on a local or global scale and which has a specific Figure 1.1 Geoid, ellipsoid, and topographic surface of the Earth, and deflection of the vertical due to differences in mass mathematical expression This shape is called the ellipsoid The separations of the geoid and ellipsoid are called geoidal heights, geoidal undulations, or geoidal separations Natural irregularities in density and depths of the material making up the upper crust of the Earth also result in slight alterations of the direction of gravity These alterations are reflected in the irregular shape of the geoid, the surface that is perpendicular to a plumb line Since the Earth is in fact flattened slightly at the poles and bulges somewhat at the equator, the geometric figure used in geodesy to most nearly approximate the shape of the Earth is the oblate spheroid or ellipsoid of revolution This is the three dimensional shape obtained by rotating an ellipse about its minor axis Where a mass deficiency exists, the Geoid will dip below the mean ellipsoid Conversely, where a mass surplus exists, the Geoid will rise above the mean ellipsoid These influences cause the Geoid to deviate from a mean ellipsoidal shape by up to +/- 100 meters The biggest presently known undulations are the minimum in the Indian Ocean with N = -100 meters and the maximum in the northern part of the Atlantic Ocean with N = +70 meters (figure 1.2) Figure 1.2 Deviations (undulations) between the Geoid and the WGS84 ellipsoid 1.1.2 The Ellipsoid a Defining the Ellipsoid We have defined a physical surface, the Geoid, as a reference surface for heights We also need a reference surface for the description of the horizontal coordinates (i.e geographic coordinates) of points of interest Since we will later project these horizontal coordinates onto a mapping plane, the reference surface for horizontal coordinates requires a mathematical definition and description The most convenient geometric reference is the oblate ellipsoid (figure 1.3) It provides a relatively simple figure which fits the Geoid to a first order approximation, though for small scale mapping purposes a sphere may be used An ellipsoid is formed when an ellipse is rotated about its minor axis This ellipse which defines an ellipsoid or spheroid is called a meridian ellipse (notice that ellipsoid and spheroid are used here as equivalent and interchangeable words) The shape of an ellipsoid may be defined in a number of ways, but in geodetic practice the definition is usually by its semi-major axis a and flattening Flattening f is dependent on both the semi-major axis a and the semi-minor axis b Figure 1.3 An oblate ellipse, used to represent the Earth surface, defined by its the semi-major axis a and semi-minor axis b The ellipsoid may also be defined by its semi-major axis a and eccentricity e, which is given by: 𝑒 = (1 − 𝑏2 𝑎2 − 𝑏 ) = = 2𝑓 − 𝑓 𝑎2 𝑎2 b Local and global ellipsoids Many different ellipsoids have been defined in the world Local ellipsoids have been established to fit the Geoid (mean sea level) well over an area of local interest, which in the past was never larger than a continent This meant that the differences between the Geoid and the reference ellipsoid could effectively be ignored, allowing accurate maps to be drawn in the vicinity of the datum (figure 1.3) With increasing demands for global surveying, work is underway to develop global reference ellipsoids In contrast to local ellipsoids, which apply only to a specific country or localized area of the Earth’s surface, global ellipsoids approximate the Geoid as a mean Earth ellipsoid The International Union for Geodesy and Geophysics (IUGG) plays a central role in establishing these reference figures Various countries recognize the different values of the ellipsoid Therefore, figures calculated in the charts projection of various countries will have differences, as a result, network of latitudes and longitudes is different at a certain value Figure 1.4 The Geoid, a globally best fitting ellipsoid for it, and a regionally best fitting ellipsoid for it, for a chosen region In 1800, according to Dalambe: a = 6375653 m, b = 6356564 m, f = 1/334 According to Haiford (US): a = 6378388 m, b = 6356912 m, f = 1/297 In 1940, according to Krasopski (Russian Federation): a = 6378245 m, b = 6356863 m, f = 0.003352329869 European benchmarks starting from Posdam (Republic of Germany) based on Hayford Ellipse in 1910, which is recognized as the international ellipsoid 1924: a = 6378388 m; f = 1/297 b = 6356912 m; e = 0.08199189 Geodetic System WGS 84: a = 6378137 m; f = / 298.36 b = 6356752 m; e = 0.081819791 1.2 Coordinates of the earth 1.2.1 Major point, line and plane on the earth The Earth is an irregular oblate spheroid (a sphere flattened at the poles) Measurements of its dimensions and the amount of its flattening are subjects of geodesy However, for most navigational purposes, assuming a spherical Earth introduces insignificant error The Earth’s axis of rotation is the line connecting the north and south geographic poles Figure 1.5 Major lines and plane on the earth The term meridian is usually applied to the upper branch of the halfcircle from pole to pole which passes through a given point The opposite half is called the lower branch All meridians are halves of great ellipses (often improperly called great circles), which converge at the north and south poles A line passing near the Royal Observatory, Greenwich (near London in the UK) has been chosen as the international zero-longitude reference line, the Prime Meridian Places to the east are in the eastern hemisphere, and places to the west are in the western hemisphere A parallel or parallel of latitude is a circle on the surface of the Earth parallel to the plane of the equator It connects all points of equal latitude The equator is a great circle at latitude 0o The poles are single points at latitude 90o The equator divides the globe into Northern and Southern Hemispheres All other parallels are small circles They are known as parallels of latitude 1.2.2 Coordinates on the earth 34 Indonesia Pilot Vol 68 35 Indonesia Pilot Vol 69* 36 Indonesia Pilot Vol 69A 37 West Coasts of England and Wales Pilot West Coast of India Pilot South Indian Ocean Pilot 70* 38 39 71 72 East Coast of the United States Pilot Vol East Coast of the United States Pilot Vol East Coasts of Central America and Gulf of Mexico Pilot West Indies Pilot Vol West Indies Pilot Vol Southern Barents Sea and Beloye More Pilot Each publication contains quality colour photography and views, as well as information on navigational hazards, buoyage, meteorological data, details of pilotage, regulations, port facilities and guides to major port entry New Editions of ADMIRALTY Sailing Directions are published on a regular basis Navigationally significant information for these publications is issued via the ADMIRALTY Notices to Mariners weekly bulletin (Section IV) 177 178 Figure 6.4 Limits of Sailing Drection Limits of the book Navigational Dangers and Hazards Navigation amongst coral Former mined areas Piracy Traffic and operations High speed craft Fishing Fishing stakes Marine farms Fish aggregating devices Submarine exercise areas Marine exploition Charts Admirlty chart Foreign charts Dutums Aids to Navigation Daymarks Buoyages Pilotage Radio Facilities Position fixing systems Radio navigational warnings Radio weather services Regulations International regulations National Navigations Signals Distress and rescue 179 Figure 6.5 Extract from Sailing Direction 180 6.2.3 Admiralty Tidal Stream Atlas A tidal atlas or a tidal stream atlas is used to predict the direction and speed of tidal currents A tidal atlas usually consists of a set of 12 or 13 diagrams, one for each hour of the tidal cycle, for a coastal region Each diagram uses arrows to indicate the direction of the flow at that time The speed of the flow may be indicated by numbers on each arrow or by the length of the arrow Areas of slack water may be indicated by no arrows or the words "slack water" An alternative to a tidal atlas is a nautical chart that provides tidal diamonds 181 Figure 6.6 Limit of tidal stream atlases Abbreviations and coverage areas of admiralty tidal stream atlases are reveals as follows: NP 209: Orkney and Shetland Islands NP 218: North Coast of Ireland and West Coast of Scotland 182 NP 219: Portsmouth Harbour and Approaches NP 220: Rosyth Harbour and Approaches NP 221: Plymouth Harbour and Approaches NP 222: Firth of Clyde and Approaches NP 233: Dover Strait NP 249: Thames Estuary (with co-tidal charts) NP 250: The English Channel 10 NP 251: North Sea, Southern Part 11 NP 252: North Sea, North Western Part 12 NP 253: North Sea, Eastern Part 13 NP 254: The West Country, Falmouth to Teignmouth 14 NP 255: Falmouth to Padstow, including the Isles of Scilly 15 NP 256: Irish Sea and Bristol Channel 16 NP 257: Portland Approaches to 17 NP 258: Bristol Channel (Lundy to Avonmouth) 18 NP 259: Irish Sea, Eastern Part 19 NP 263: Lyme Bay 20 NP 264: The Channel Islands and adjacent Coast of France 21 NP 265: France, West Coast 22 NP 337: The adjacent waters Selent and 183 Figure 6.7 Cover of tidal stream atlas This atlas contains 13 charts showing tidal streams at hourly intervals commencing hours before HW Dover and ending hours after HW Dover The times of HW Dover and other details of the prediction for this port are given in NP 201 Admiralty Tide Tables Vol which is published annually N P 201 also gives tidal predictions for a number of ports and tidal stations in the area covered by this atlas On the charts the directions of the tidal streams are shown by arrows which are graded in weight and, where possible, in length to indicate the approximate rate of the tidal stream Thus, indicates a weak stream and indicates a strong stream The figures against the arrows give the mean neap and spring rates in tenths of a knot thus: 19.34 indicates a mean neap rate of 1.9 knots and a mean spring rate of 3.4 knots The comma indicates the approximate position at which the observations were obtained Computation of Rates-Example Required to predict the rate of the tidal stream off Start Point at 0400 on a day for which the tidal prediction for Dover (extracted from N P 201) is: 0100 5.8m 0743 0.1 m 1234 5.8m 2006 0.1m Mean Range of tide at Dover for the day is 5.7m Point) of 11.20 (1.1 kn.2.0kn) Enter the diagram Computation of Rates opposite with these mean neap and spring rates Joining the dots representing them with a ruler From the intersection of this line with the horizontal line rep resenting the range at Dover (5,7m) follow the line vertically to the scale of Tidal Stream Rates (top or bottom) and read off the predicted rate-in this example 1,9 knots 184 Figure 6.8 Graph of computaions of rates 6.2.4 Annual summary Notice to Mariners The annual summary of admiralty notices to mariners, also popularly known by its publication number NP 247 (1) and (2), is a publication issued by admiralty (UKHO) on yearly basis The notices advice mariners on important matters related to ship’s navigation, hydro graphic information, aids to navigation, and changes in shipping channels The current edition of Notices to Mariners, superseding and cancelling the previous one, is divided into two sections This annual summary is of prime importance to mariners in keeping navigational chart folio up to date for corrections pertaining to temporary and preliminary notices for ship’s navigation and sailing directions The annual summary serves as a database with details of history of 185 Figure 6.9 Cover of Annual Summary NM corrections for all the charts and sailing directions published by the British Admiralty or UKHO The Annual Summary of Admiralty notices to mariners is divided into two parts: NP 247(1) NP 247(2) Contents of NP 247(1): In this publication the contents are in two sections namely – Section – Annual Notices to Mariners Section – Temporary and Preliminary Notices Starting with an index which consists of a note displaying that the current annual summary replaces the previous one, which should be cancelled and destroyed, the first section deals with annual notices for the current year for e.g an edition of 2013 of Annual summary would deal with notices applicable till the end of year 2012 comprehensively A detailed index of notices is provided regarding navigational importance with respect to the British Isles, along with vital information about tide tables, suppliers of admiralty charts and publications, safety of British ships in event of war crisis, voluntary reporting schemes, firing practice areas, mine laying operations, protection of historic, dangerous and military wreck sites etc The publication also includes an exhaustive list of traffic separation schemes and information related to ship routeing system shown on admiralty charts It contains port state notifications issued under the EU Directives and some parts of ship navigation related regulations issued by the United States The annex provided with the notice contains extracts from the US navigation safety rules The second important section of the navigation publication contains a numerical index of temporary and preliminary notices which are in force 186 since the end of the previous year The index is preceded by further detailed description of each notice mentioned in it, thus enabling mariners to check any chart or any T & P correction applicable to the chart right from its edition date This information is significant for mariners to keep a track of any previous notice that has been missed out, cancelled or not in force any further Mariners can thus always refer to the Annual Summary and keep their navigational chart folios up to date Important Notes: Often during Oil Major Inspections observations, navigational charts are found marked with Temporary and Preliminary notices which are no more in force or have been cancelled or some notices are found missing Thus while preparing for such inspections, the ship’s navigating officer can always refer to Annual Summary of Notice to appraise the status of corrections before planning passage in order to keep navigational charts up to date 6.2.5 Notices to Mariners (NMs) The weekly Notices to Mariners contain, amongst other information, individual notices (not to be confused with the NM itself) A NM is broken up into the following sections: - Section I – Explanatory Notes and list of Publications - Section II – Geographical Index Index of Affected Charts: matches chart numbers affected with notice Corrections to Charts: individual notices to be used in chart correction 187 Figure 6.10 Cover of Admiralty Notices to Mariners Temporary and Preliminary notices in force at time of publication of NM - Section III – Reprints of Navigational Warnings (in force) - Section IV – Amendments to Admiralty Sailing Directions (not for charts) - Section V – Amendments to Admiralty List of Lights (not for charts) - Section VI – Amendments to Admiralty list of Radio Signals (not for charts) Sections IV through VI are used for correcting other Admiralty publications in use on board and not charts Some of these publications are the List of Lights and fog signals, Sailing Directions, Admiralty list of Radio Signals etc There are hundreds of such publications on board, depending on the trade of the ship and the voyages she is likely to make 6.2.6 Cumulative Notices to Mariners To assist mariners in chart correction, the British Admiralty started publishing these in addition to the weekly NMs a couple of decades ago The salient features of the Cumulative NMs are as follows: June Published biannually, Jan and - Contains the numbers of all Notices affecting all the charts that exist for the last years - Latest edition dates of each chart are marked The mariner can then, at a quick glance, check that 188 Figure 6.11 Cumulative List of Admiralty Notices to Mariners He has the latest edition of each chart on board (new editions of charts are published regularly, just like books When this happens, the older editions are defunct and must be replaced) Since he can read off the notices affecting each chart for the last two years, he can confirm that all corrections on board have been made and marked on either the chart itself, or in the separate chart correction log Note that the Cumulative NM does not give any details of the small corrections like T/P notices and Nav warnings 6.2.7 Admiralty tide Tables (NP 201-208) ADMIRALTY Tide Tables detail the times and heights of high and low waters for over 230 standard and 6000 secondary ports in the UK and Ireland, Europe, the Indian Ocean, South China Sea and Pacific Ocean for each day of the year The tables outline methods of prediction, the effect of meteorological conditions on tides and provide additional information on exceptional tidal factors in each area Figure 6.12 Limits of Admiralty Tide Tables 6.2.8 The Mariners Handbook (NP100) 189 A comprehensive guide to seamanship and key aspects of maritime navigation Content includes essential information on charts and their use, the communication of navigational information, the maritime environment, restrictions to navigation and maritime pollution and conservation The latest edition offers: - Simple tabular layouts to help mariners quickly locate essential information - Inclusion of QR codes to help mariners ensure that information is always up-to-date Weekly electronic updates and simple search functionality when brought as an e-NP Figure 6.13 Limits of Admiralty Tide Tables 6.2.9 The Admiralty List of Radio Signals The ADMIRALTY List of Radio Signals series provides comprehensive information on all aspects of Maritime Radio Communications The data is organised into six volumes, some divided into several parts for ease of handling Each of the six volumes is presented in a user-friendly format with full colour photographs and diagrams The contents range from a complete listing of stations handling Maritime Public Correspondence to a full range of products and services essential for compliance with the GMDSS (Global Maritime Distress and Safety System) The volumes also feature radio stations broadcasting weather services and forecasts and a detailed explanation of the complexities of Global Satellite Position Fixing Systems ALRS publications are presented in 190 a user-friendly format and are updated through Section VI of the weekly editions of ADMIRALTY Notices to Mariners New Editions are published annually containing all changes to information held NP281 (Parts & 2) - Maritime Radio Stations NP282 - Radio Aids to Navigation, Satellite Navigation Systems, Differential GPS (DGPS) Legal Time, Radio Time Signals and Electronic Position Fixing Systems NP 283 (Parts & 2) - Maritime Safety Information Services NP 284 - Meteorological Observation Stations NP 285 - Global Maritime Distress and Safety System (GMDSS) NP 286 (Parts - 8) - Pilot Services, Vessel Traffic Services and Port Operations 191 ... Flattening, 1/ f Airy (18 30) 6377563.396 299.324964 Everest (18 30) 6377276.345 300.8 017 Bessel (18 41) 6377397 .15 5 299 .15 2 813 Clarke (18 66) 6378206.4 294.978698 Clarke (18 80) 6378249 .14 5 293.465... meridians L and L :