A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2009 Oct 23, 13:55 -0400
Latitude by Length of day for Emergency Navigation. Hmm.
Assuming that your latitude didn’t change during the course of the day
You can determine the instant of sunrise, independent of refraction
You can determine the instant of sunset, independent of refraction
The declination of the sun is not zero or close to it
Your watch doesn’t vary
you can probably tell your latitude within a degree.
Whoopee! Still don’t know our longitude. Still have no idea where we are. Fiddling around in the ocean in a lifeboat, sailing down a latitude line that will be vary north south in a drunken sailor walk.
The clearest survival advice offered to any shipwreck survivor is to STAY PUT and wait for the cavalry. Better yet, bring an EPIRB that sends your GPS position to the satellites on 406 MHz with a mayday message and that also sends a beacon on the 121.5 MHz for Radio Direction Finding when they get close. Looks expensive when you don’t need one. Super cheap the moment you do!
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