Description
Book SynopsisThe 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 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 e
Trade ReviewA book for the highly competent navigator...but also for those who feel a headache at the very sight of astro-navigation tables... The reader who set out to do only the minimum finds herself imperceptibly beginning to wonder what she did with that old sextant she put away in despair long ago. -- Julia Jones * Yachting Monthly *
The author guides the reader through the subject, demystifying the aspects hat have stymied many would-be practitioners over the years. * Classic Boat *
From the moment one picks it up
The Practical Guide to Celestial Navigation impresses as being well-produced. It would make an excellent present for any skipper planning a long passage – total reliance on electronics is never a good idea – and will keep them occupied for many hours thereafter. * Flying Fish *
Beautifully written. All the theory and practice is explained clearly with well-illustrated diagrams * Practical Boat Owner *
Experienced yacht sector instructor Phil Somerville has produced a superbly engaging educational resource… Even a maritime novice may be inspired to dream of mastering this timeless skill. * Nautilus Telegraph *
Guides to reader through the subject, demsytifying the aspects that have stymied many would-be practitioners over the years. * Sailing Today *
Comprehensive, practical…with helpful full-colour illustrations…you’ll quickly be able to put Somerville’s fascinating guide to practice once you’re onboard your boat. * Lifeboat Magazine *
The beauty of this book is that it demystifies the subject and explains it in clear and concise language, liberally supported by diagrams and evocative photographs. * Cruising *
Table of ContentsAbout 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
