Lifeboat Navigation

The Lifeboat Navigation App
In 1946 Harold Getty wrote a book called 'The Raft Book'. His aim was to write a manual for 'LifeBoat Navigation'. A manual that all ships would carry in their lifeboats. The manual would assist navigators who had the misfortune to have to abandon ship and find their way to land.
The story inspired me to design an app that would be available to everyone who would ever be in the same unfortunate circumstances, or for those who had the misfortune, for some reason, to be without a GPS.
The app is designed to incorporate some of the methods the Polynesians used, and also to design some method to find land without the aid of a 'professional' sextant or GPS.
Most importantly, the app had to be useful for people with no real prior learned navigational skills.
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The first two calculations are Mercator Sailing, and Dead Reckoning. Working out distances and courses to steer, and distance and course run, over a period of time.
This way you know where you are coming from and going to. A huge improvement on not knowing where you are!
Followed by two simple methods for finding your latitude and longitude. These calculations are improvements on your Dead Reckoning positions.
Next we discuss how to measure the altitude of a celestial body without a sextant. Instead, from Harold Getty's book, 'the Harp'. Nothing like a sextant, but a means to estimate the altitude of celestial bodies. All you need is a piece of wood, a string and a ruler.

If you liked and learned from the first part, then the next part will put you on the road to becoming a Polynesian navigator.
You will find stars to navigate from in the Starfinder. 58 Stars from the Nautical Almanac with an easy method for identification.
A 'Subpoint' calculation for steering towards stars, of which you will have calculated the point in the sky, where these stars are overhead. An important piece of the puzzle of Polynesian navigation.
I hope you will enjoy learning to navigate the Polynesian way!

'On a clear night, you could never lose the stars,
and with them you could never be truly lost'
(David Baldacci)