The Practical Guide to Celestial Navigation

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 YachtmasterT 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