NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bermuda to St Helena on a North Atlantic Mercator Chart
From: Lars Bergman
Date: 2021 Dec 29, 10:31 -0800
From: Lars Bergman
Date: 2021 Dec 29, 10:31 -0800
David wrote "There isn’t a difficulty. It’s proving the thesis that, if the great circle is north of the rhumb line in the Northern Hemisphere and south of the rhumb line in the Southern Hemisphere, then the great circle and the rhumb line must cross the Equator at the same longitude that concentrates the mind."
The GC and RL cross the equator at the same longitude only if the start and end positions are symmetrical, i.e. the same latitude but different names. For the Bahamas to St Helena case the GC cross the equator at W 23°5' and the RL cross the equator at W 24°36', calculated for a spherical earth. And the difference in distance Bahamas to St Helena is only 7.4'.
Lars
