NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun altitude limits for natural horizon?
From: Hewitt Schlereth
Date: 2016 Feb 20, 16:09 -0800
From: Hewitt Schlereth
Date: 2016 Feb 20, 16:09 -0800
Ron, the ship was about one hour west of Greenwich. If the times for the sights are GMT, the ship's local times would be roughly an hour earlier.
The 2016 almanac gives Civil twilight at latitude 10* South on Jan 29 as 1852, so it might make sense that way.
Hewitt