NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2023 Nov 22, 07:55 -0800
David McM you wrote: It doesn't matter.
I presume you meant you could use either start, middle, or end latitude, and it won’t make much difference. Doesn’t it depend upon your start latitude, because of the shape of the cosine curve?
E.g. you sail from 9.5°N, cmg 060 , dist gone = 120. Therefore, your northing = 60nm and your end lat = 10.5°N. Find Ch long using cos 9.5°N and cos 10.5°N and note the difference in ch-long.
Then do the same but starting from 59.9°N, and use cos 59.5° and cos 60.1°N, and not the difference in ch-longs.
Might it have been OK for Bligh in Bounty’s launch to use start, mid, or end lat, but not OK for Noggin the Nog in his longship, even if you divide the 60N difference in ch-long by 2 to turn it back to nm? DaveP
