The Complete On-Board Celestial Navigator, 2007-2011 Edition: Everything But the Sextant

By George C. Bennett

Your All-in-One Navigation Tool Kit

Celestial navigation remains an essential skill for every mariner who ventures out of sight of land. In this era of electronic navigation, it is the perfect backup system, enabling you to determine your position when the GPS malfunctions or your boat loses electrical power.

Here in one volume is every bit of information you need to understand the process, take sights, and find your location anywhere in the world. Compiled for beginning and experienced celestial navigators alike, and elegantly designed on the assumption that 1-mile precision is perfectly adequate for backup navigation, this handy volume replaces $300 worth and thousands of pages of guides, tables, and almanacs.

The Complete On-Board Celestial Navigator includes:

• A clear, concise primer/refresher that explains the entire process
• A five-year nautical almanac (2007–2011) for determining precise star, sun, moon, and planet locations at the time of sighting
• A star finder
• Sight reduction tables for crunching the numbers and producing a fix anywhere in the world

"The only complete self-contained work available. When your electronic navigation fails, 'steering by the stars' will guide you safely to your destination."—Sydney Afloat (Australia)

• Language: English
• Publisher: McGraw-Hill Education
• Release date: Dec 25, 2006
• ISBN: 9780071818629

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Copyright © 2007 by International Marine. All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.

ISBN: 978-0-07-181862-9

MHID:       0-07-181862-6

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CONTENTS

PART ONE: HOW TO WORK A SIGHT-AN OVERVIEW

1 INTRODUCTION

2 SCOPE AND CONTENTS

3 EQUIPMENT

3.1 Sextant

Perpendicularity Error

Side Error

Index Error

3.2 Clocks

4 ALMANAC DATA

4.1 Stars and Aries

4.2 Sun and Planets

4.3 Moon

4.4 Summary

4.5 Alternative Interpolation Method

5 PLANNING AND OBSERVATIONS

5.1 Planning

5.2 Sextant Observations

5.3 Identification

5.4 Observation Methods

5.5 Sunrise, Sunset, and Twilight

6 SEXTANT ALTITUDE CORRECTIONS

6.1 Dip Correction

6.2 Index Correction

6.3 Star and Planet Corrections

6.4 Sun Correction

6.5 Moon Correction

6.6 Summary

7 THE MARCQ ST. HILAIRE METHOD

7.1 Intercept

7.2 Azimuth

Azimuth Tables

Weir Diagrams

7.3 The Position Fix

8 AMPLITUDES

9 POLARIS

9.1 Azimuth

9.2 Latitude

10 SUN OBSERVATIONS

10.1 Running Fixes

10.2 Meridian Observations

11 SIGHT REDUCTION AT VERY LOW ALTITUDES

PART TWO: TABLES, EXAMPLES, AND FORMS

Constants and Formulas

GHA Aries and Star Ephemerides

Sun and Planet Ephemerides

Sun and Planet Interpolation and Altitude Corrections

Moon Ephemerides

Moon Declination Interpolation

Moon (GHA-GMT) Interpolation

Moon Altitude Corrections

Sextant Altitude Analysis Example

Prediction and Identification

LAT of Sunrise and Sunset

LAT of Civil Twilight

Sight Reduction Tables

Azimuth Tables

Weir Diagrams

Polaris (Latitude and Azimuth)

Change of Altitude in 5 Minutes of Time

Sight Reduction Example: Stars, Planet, and Moon

Running Fix Example: Sun

Alternative Interpolation Table (Calculator)

Form: Sextant Altitude Analysis

Form: Sight Reduction

Form: Sight Reduction (Plot)

THE NAVIGATIONAL STARS

INDEX

CONVERSION OF TIME TO ARC

PART ONE: HOW TO WORK A SIGHT—

An Overview

The Note Numbers refer also to the Line Numbers on the Sight Reduction Form (see page 168). You will find it more efficient if for most of the work, you proceed across the Sight Reduction Form rather than work column by column. In order to keep interpolation errors to a minimum many of the tables are arranged in critical form. If you find your data entry coincides with a tabulated value then take the upper (up the page) value of the correction.

1 Indicate the day of the week as an additional check on the date.

2 The name of the body as identified.

3 It is preferable to use a digital rather than an analogue watch; there is less chance of making a reading mistake.

4 Determine the watch correction by comparing the watch with another timepiece whose error is known or with a Radio Time Signal, e.g., WWV(Colorado) &WWV(H) (Hawaii) U.S.

5 Standard Time or Zone Time, i.e., time referred to a given Time Zone.

6 Time Zones, with a few exceptions, are an integral number of hours.

7 The date of this GMT will change from that given in line 1