The Practical Guide to Celestial Navigation

THIS EBOOK EDITION IS DESIGNED TO BE EXPERIENCED ON COLOUR DEVICES
The practical guide to celestial navigation - know what to do step by step, understand why you're doing it, and be confident that you can put it into practice when on board.
Did you know that a person standing on the equator is effectively travelling at 900mph? And did you know that you can use this information to work out where you are in the world, to an accuracy of about 3 or 4 miles? No GPS, no computers. Just a sextant, some tables from an Almanac and the knowledge in this book.
It's the only back up if the GPS goes down, so it's a matter of safety. If you want to qualify as a commercial skipper/superyacht captain you need to know how to carry out celestial navigation. And if you want to pass the RYA Ocean Yachtmaster(TM) exam, you need to know it too. It's a major stumbling block for many sailors wanting or needing to take their next qualifications, and the other books on the market are complex and often assume some prior understanding. This book fulfils the need for a clear explanation of celestial navigation, illustrated with colour diagrams and including unique checklist sheets to enable you to repeat all those calculations you learned back at home, when you're on deck.
Without overwhelming the reader with a load of theory from the off, the author breaks down what you need to do, step by step, explaining why at every point - giving the information context, and making it more interesting and memorable. He has trained students in this subject for years, and here he's able to use his experiences of what works, and what are the common pitfalls - he even includes a troubleshooting chapter near the end, going through errors commonly made, and how to spot them. The objective is that readers will finish the book not only knowing what to do, but really understanding why, and being able to make sense of it all again later (rather than just getting through and exam and finding themselves at a loss when on deck). The author also includes time-tested 'proformas' - quick reference sheets that sailors can refer to when they come to putting the theory into practice on board, avoiding the terrifying 'cold start' that most sailors experience when they suddenly need to put their theoretical knowledge to the test in the real world.

Phil Somerville has been teaching Celestial Navigation for nearly a decade to RYA Ocean and MCA Superyacht candidates in the UK, Spain, Italy and France (at numerous RYA & MCA training centres). Teaching in the winter months, in the summer he has worked on the likes of Skip Novak's Patagonia-based Pelagic Australis (a 23-metre expedition vessel designed for high latitude sailing).

About the author
Acknowledgements
Introduction
A bit of history
Why bother?
A bit about this book
Chapter 1 The basics
Latitude and longitude
Earth rotation
Great circles
Chapter 2 Foundation of celestial navigation and the geographical position
Geographical position (GP)
Position lines and lines of position
Chapter 3 Defining the geographical position
Declination
Greenwich Hour Angle (GHA)
Obtaining the sun's GP
Proforma introduction
Chapter 4 Sextant corrections
Index error
Height of eye (dip)
Altitude correction
Applying the corrections: example
Chapter 5 The PZX triangle
A bit of background
Chapter 6 The intercept method
Chapter 7 Sight Reduction Tables
The four keys
Chapter 8 Undertaking a full sight reduction
Resources
Sight reduction
Chapter 9 Sun sight reduction - Quick Start and recap
Resources
Completing a sun sight reduction
Chapter 10 Meridian passage
How we take the sight
Worked example
Resources
Chapter 11 Meridian passage - Quick Start and recap
Resources
Completing a meridian passage sight
Chapter 12 Plotting
Sun Run Sun: morning sun sight and meridian passage
Plotting a Sun Run Sun
Sun Run Sun: morning sight and afternoon sight
Sun Run Sun: meridian passage and afternoon sight
Chapter 13 Compass checking
Variation
Deviation
Sight reduction for compass checking
Checking for deviation
Worked example
Chapter 14 Time
Time zones
Chronometer
A practical solution for accurate timekeeping
International Date Line
Chapter 15 Sextant: Practical aspects of sight taking
Overview
Errors
Undertaking a sight
Reading the sextant
Sextant care
Chapter 16 Troubleshooting
Appendices
1. Sun sight proforma
2. Sun sight proforma guide
3. Meridian passage proforma
4. Meridian passage proforma guide
5. Plotting sheet
6. Plotting guide
7. Longitude scale plotting
8. Z versus Zn
9. Assumed longitude
10. Adding and subtracting of 60ths
11. Polaris
Glossary
Index