Re: Celestial Navigation: Nautical Almanac
For sun sights , almanacs repeat themselves every 4 years. So get 4 years in a row and you have all the backup you need for sun sights. Even one several years out of date is only about three miles out on sun sights.
I can tell people how to take a noon sight in about 5 minutes.
Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"