Navigating by the heavenly bodies is one of the oldest of the mariner's arts -- and one of the most awe-inspiring. It is also essential for every ocean sailor who wants to be able to fix his position should the GPS fail.
In the book, Celestial Navigation, Tom Cunliffe shows how to master the art in easy stages. Today he talks about Using Sextant Shades.
Read more at: http://www.wileynautical.com/celestial