Course / Guides
Celestial navigation guides
Short, plain answers to the questions people ask first. Each one leads into the lessons that teach it.
- Celestial navigation for beginnersHow a sextant angle becomes a position, what you need, and where to start.
- How to use a sextantTaking a sight: index error, bringing the body down, rocking, timing, correcting.
- The intercept methodMarcq St. Hilaire in plain words: Ho, Hc, toward or away, and the line of position.
- Pub. 249 vs Pub. 229What each table covers, how precise it is, and which to carry.
- How accurate is celestial navigation?What to expect from a small boat, where the errors come from, and how to shrink them.
- How to learn celestial navigationOnline or from books: what works, and what to practice.
- GlossaryEvery term, with the lesson that teaches it.
Free tools
- Noon sight calculatorThe time of local noon, and your latitude from the Sun's noon altitude.
- Sun almanacThe Sun's GHA and declination for every hour of any date, 2026 to 2028.
- Polaris latitude calculatorLatitude from the Pole Star, with the a0, a1 and a2 corrections.
- Star finder (2102-D)A working 2102-D: the altitude and bearing of every navigational star at twilight.