Practical Navigation for the Modern Boat Owner
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Practical Navigation for the Modern Boat Owner PAT MANLEY Practical Navigation for the Modern Boat Owner Practical Navigation for the Modern Boat Owner PAT MANLEY Copyright © 2008 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (ϩ44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to [email protected], or faxed to (+44) 1243 770620. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The Publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the Publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Other Wiley Editorial Offi ces John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA Wiley-VCH Verlag GmbH, Boschstr. 12, D-69469 Weinheim, Germany John Wiley & Sons Australia Ltd, 42 McDougall Street, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore 129809 John Wily & Sons Canada Ltd, 6045 Freemont Blvd. Mississauga, Ontario, L5R 4J3 Canada Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Library of Congress Cataloging-in-Publication Data Manley, Pat. Practical navigation for the modern boat owner / Pat Manley. p. cm. Includes index. ISBN 978-0-470-51613-3 (cloth : alk. paper) 1. Navigation–Handbooks, manuals, etc. 2. Global Positioning System–Handbooks, manuals, etc. I. Title. VK555.M267 2008 623.89–dc22 2008003730 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN-13: 978-0-470-51613-3 (HB) Typeset in 10/12 Futura by Thomson Digital, Noida, India Printed and bound in Italy by Printer Trento, Trento Contents Contents Cover Points xi Foreword xiii Introduction xv 1 The Global Positioning System 1 How Your GPS Receiver Tells You Which Satellites It Can See 2 How GPS Works 3 Accuracy of the Fix 4 GPS Blackout 5 Deliberate Interference 5 GPS Is Line of Sight 5 Selective Availability 6 Differential GPS 6 Wide Area Augmentation Service 6 Switch-On Delays 7 Measurement of Speed 8 Measurement of Course 8 Measurement of Heading 9 Errors in COG and SOG 9 2 Our Address on the Earth’s Surface 11 The Equator 12 Latitude 12 v Greenwich Meridian 12 Longitude 12 Our Address 13 International Date Line 13 Measurement of Latitude and Longitude 13 Distance and Direction 14 Direction 16 The Flat Earth 19 The Spherical Earth and ‘Map Data’ 20 Chart Errors 22 Chart Scale 24 Measuring Latitude and Longitude 25 Chart Symbols 26 3 The Magnetic Compass 29 The Earth’s Magnetic Field 30 Steering Compasses 30 Compass Deviation 31 Compass Correction 31 DIY Compass ‘Swing’ 31 Fluxgate Compasses 33 4 Constructing a Route 35 Using Second-Hand Waypoints 36 Loading the Route into the GPS 38 Constructing a Route on an Electronic Chartplotter or PC 38 5 Tides 39 Tidal Heights 39 Tidal Flow 50 Finding the Value of the Tidal Flow 52 6 Boat Speed 57 Speed over the Ground 57 Speed Through the Water 58 Measuring Speed Through the Water 58 Log Errors 58 vi Contents 7 Depth Sounders 61 How They Work 62 Depth Units 62 Calibration 62 Depth Alarms 63 False Echoes 63 Fishfi nders 63 8 Finding Position 65 GPS 65 Other Methods 66 Position Lines 67 Fixing Your Position Using Position Lines 69 Errors in Position Lines 70 How Far Can You See? 71 When All Else Fails 72 Chartplotters 73 9 Passage Planning 77 Overview 78 Detailed Plan 79 Just Prior to Departure 80 Passage Planning – Procedure 81 Preplan 81 For the Planned Day of Departure 81 Passage Making 81 Passage Grid 86 Approach ‘Spider’s Web’ 86 Compass Rose as a Waypoint 87 Unmarked Danger as a Waypoint 88 Clearing Bearing 88 10 Pilotage 89 Who Does the Piloting? 90 Means of Pilotage 90 International System of Buoyage 90 vii International Buoyage – All Areas 92 Planning 97 The Basics of Preparing a Pilot Plan 97 Making a Pilotage Plan 98 Working as a Team 101 11 A u t o m a t i c I d e n t i fi cation System 103 What is Automatic Identifi cation System? 104 How Does AIS Work? 104 Class A AIS 104 Class B AIS 104 AIS Displays 105 The AIS Display on a Chartplotter 106 AIS Class B Transceiver 107 12 Radar 109 How Radar Works 110 Navigation Using Radar 113 Pilotage Using Radar 114 Radar Overlay on a Chart Plotter 121 Setting up Your Radar 121 Radar Used for Collision Avoidance 122 13 Autopilots 125 Types of Autopilot 125 Using the Autopilot 126 14 Personal Computers 129 What Type of PC 130 What Make of Chart-Plotting Software? 130 What Type of Electronic Charts? 131 Electronic Charts for PC Based Chartplotters 132 Selecting the Software 133 Constructing a Route 134 Sailing Yacht Route Planning 135 viii Contents Sending the Route to the GPS 137 AIS on a PC 138 Radar on a PC 139 Navtex on a PC 142 Tides on a PC 142 Connecting to the Boat’s Systems 143 Appendix A Deduced Reckoning and Estimated Position 145 DR Navigation 146 Estimated Position 146 Leeway 148 Error in EP 148 EP with Multiple Headings 148 Appendix B Course to Steer 149 Where Do You Want to Go? 150 What Time Interval Do You Choose? 150 Draw in the Tide 151 Draw in the Boat Speed 151 Ground Speed 152 Comparison with EP 153 Appendix C Tidal heights and Tidal streams 155 Atmospheric Pressure Corrections 156 Tide Tables 156 UKHO Tidal Predictions 156 SHOM Tidal Predictions 159 Tidal Streams 161 Appendix D Tidal Planning and Plotting 165 A Long Passage Using a Single CTS 165 Where will the Tide Take You? 167 Credits 169 ix Cover points Cover points • If you wonder why your in-car navigator shows that you are in a fi eld – Read on • If you wonder why your in-car navigator takes you on farm tracks – Read on • If you think that the electronic charts on your chartplotter are accurate – Read on • If you want to know the depth of water over the rocks – Read on • If you think pressing ‘GO TO’ will take you safely to your destination – Read on xi Foreword Foreword The methods of navigation used by the modern boat owner have changed quite rapidly from the traditional methods still currently taught. This doesn’t make the old methods wrong; it just means that the emphasis has changed. With GPS used in many cars, the level of computer skills of the general public being high, and the so-called paperless offi ce, the modern boat owner desires a different approach to navigation. ‘Practical Navigation for the Modern Boat Owner’ will lead you through all aspects of navigation of your boat in a logical order. The pencil and paper chart part of the subject is not introduced until it’s demonstrated that some knowledge of traditional navigation is necessary. This practical approach to the subject will ensure that although the modern electronic methods of navigation remain at the forefront, the reader will never be lacking in suffi cient knowledge to navigate his/her boat safely in any circumstance. Proper passage planning is not only desirable, but it is also a legal requirement. This topic is thoroughly covered in an entirely practical manner. The boat owner cannot rely entirely on electronic navigation for pilotage. Pilotage will introduce the well-established and practical aspects of entering and leaving a harbour or anchorage. Radar is another area where legally the boat owner is required to know how to use this valuable tool. Again, this topic is approached using a practical and easily understood approach. xiii Introduction Introduction When I gained my Flight Navigator’s License in 1973, other than when I was actually on the ground, I never knew where I was, only where I had been! By the time you had worked out and plotted a fi x, you were at least 60 miles further on. Even when I fl ew Boeing 747s, without a Flight Navigator, the inertial navigation system, which used three onboard gyroscopic platforms to measure acceleration in all three planes to determine where you were, could be 10 miles in error by the time you had fl own 12 hours. Incidentally, the Apollo spacecraft to the moon used only one of these inertial systems for navigation! Modern airliners use a combination of inertial navigation systems continually updated by automatically tuning into ground-based aids to remove any inherent errors.