Table of Contents

Class Prep

Class 1
Class 2
Class 3
Class 4
Class 5
Class 6
Class 7
Class 8
Class 9
Class 10

>>Topical Articles<<
Assumed Longitude
Casio fx-260 Solar II
Emergency Navigation
Making a Kamal
Noon Sight
Pub. 249 Vol. 1
Sextant Adjustment
Sextant Skills
Sight Averaging
Sight Planning,
  Error Ellipses,
  & Cocked Hats
Slide Rules
Standard Terminology
Star Chart
The Raft Book
Worksheet Logic

The Raft Book, by Harold Gatty

This is an amazing book on emergency navigation that was published during World War 2, intended for the use of sailors and airmen who had been set adrift. Occasionally copies of this book come up for sale on eBay. But the heart of the book is in two navigational charts, which you can download here.

Chart 1 works because the declination of the stars does not change.* With a sextant, you could view the altitude of stars and work out your own latitude. Assuming you had a sail and could steer, you could ensure that you landed on an Allied-held island rather than a Japanese-held island.

To faciliate noon sights, the declination of the sun was indicated graphically along the right edge of the chart.

Chart 2 contains another star chart, plus tables to allow you to make a determination of your latitude by duration of the day. So then, even lacking a sextant, if you had a watch on board your lifeboat, you could get a moderately good idea of your another chart to give you a rough idea even of your longitude.

I don't know whether anybody ever actually used this chart in lifeboat navigation...but the concise presentation of a vast array of navigational knowledge makes these charts an astonishing achievement.

Every so often a copy of The Raft Book will appear on eBay. I always think about buying a copy, but have never quite gotten to it. I did just recently order Finding Your Way without Map or Compass by Gatty. I'll tell you what I think of it after I have a chance to spend some time with it.

* It is not completely true to say that the declination of the stars does not change. It does change, but on a 27,000 year cycle. Like a gyroscope, the earth precesses in its rotation. This means that in a few centuries, Polaris will no longer be the pole star. However, wait 27,000 years, and again Polaris will be the pole star.

Precession is the reason "the First Point of Aries" is not found in the constellation Aries. It WAS located in Aries when Hipparchus defined it in 130 BC, but now 2000+ years later, it is in the constellation of Pices. Soon (where "soon" is defined in terms of a 27,000 year process) it will move into the constellation of Aquarius. Astrology has had the idea that when the First Point of Aries gets into Aquarius, it will usher in an age of greater peace and understanding. Hence a popular song from 50 years ago, Age of Aquarius.

In the year 26,870 or so, the first point of Aries will again be in the constellation Aries.

The stars themselves do actually move in their apparent positions, and indeed our solar system itself is moving about the galaxy. This is called the "proper motion of stars" - but like precession, this takes place on a scale of thousands of years. Click here for an interesting simulation of proper motion.

In any case, you can get the current declination of the stars from the latest version of the Nautical Almanac. The values there are guaranteed to be accurate.