Introduction

Introduction When a recent computer glitch hit navigation systems, alarm bells began to ring throughout aviation and maritime circles. Were problems with the Satellite-controlled Global Positioning System (GPS) a foretaste of far greater difficulties to come?

We were warned about this problem just as we were warned about the Millennium bug and so we had time to prepare. Yet what if some other disaster were to strike without warning, such as the destruction of satellites by meteorites or the malfunction of computer systems through viruses? Severe solar storms could knock-out all radio services, both terrestrial and satellite based, thereby making it impossible to use automated radio navigation aids and even GMT time signals. In such circumstances, how would navigators navigate?

It was concerns such as these that led to this book being written in an attempt to re-kindle interest in the traditional art of navigation.

The book has two main aims. Firstly, to provide a resource for those who wish to study the principles of astro-navigation. Secondly, to provide a system of astro-navigation which could be used in circumstances where navigators are faced with problems caused by failure of satellite navigation systems. What is more, the system does not rely on the use of chronometers or nautical almanacs and for this reason it could safely be used in circumstances where such aids are not available.

Those who would like to learn the full method without necessarily developing full understanding of the underlying principles, could go directly to chapter 9. There is a step-by-step demonstration of the full method in this chapter and the exercises in chapter 13 give further opportunities to practise it.

Those who haven't got time to read the book thoroughly enough to learn the full method but who need a simple method of finding their position in a survival situation could go directly to appendix 4. This appendix contains a simple method of calculating a position in terms of latitude and longitude from the altitude of the Sun and the time in GMT at noon, local time. This method could prove to be invaluable in a survival situation such as being castaway in an open boat, being in a storm-damaged yacht in mid-ocean or even when competing in an ocean rowing race.

Astro-navigation is a fascinating subject that encompasses many areas of knowledge including geography, astronomy, history and mathematics. As you unravel the principles and techniques upon which navigation is based, you will be left in awe of the sheer genius of the ancient scholars and mariners who developed the art over the centuries to a highly sophisticated form.

Yet, sadly, the art of astro-navigation lies dormant. The ever-increasing demands for speed and simplification and the ever-decreasing time available for training in navigation, coupled with phenomenal advances in technology have resulted in navigators relying almost completely on automated navigation systems.

Russia is one of the few countries in the world to acknowledge the educational value of astro-navigation and to include it as an important part of the school curriculum. It is hoped that this book will lead to a re-discovery of the subject in other countries.

The book will take you on a voyage of discovery in search of knowledge of the principles underlying astro-navigation. It will also help you to appreciate the inter-relatedness of the various disciplines that are encompassed by the subject, for which mathematics provides the binding medium. It will appeal to anyone with a fascination of the sea. In particular though, it has been designed to provide invaluable knowledge and understanding of astro-navigation and related mathematical techniques both for sea-farers and for mathematics students.

Few navigation books describe techniques that involve first principles; instead they mostly describe methods which rely upon the use of tables of computed data and rote-learned procedures. There is obviously very little educational value in such techniques; far better that students should be helped to discover and apply the underlying principles for themselves.

For this reason, the underlying philosophy of this book is that students should be encouraged to discover the fundamental principles upon which astro-navigation is based. Therefore, my aim is to provide a resource to help people to learn to navigate by the Sun without the aid of automated navigation systems, `ready-reckoners', nautical almanacs, or other sets of astronomical data.