A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Chris Mitchell
Date: 2019 Sep 27, 06:27 -0700
Thanks to everyone who have chimed in on this topic, and provided some clarification to the issue.
Frank, when I asked "would it be safe to say that this method of finding longitude and local apparent time was replaced with by more modern longitude by chronometer method and UTC?" I should have been more specific. I realize now that there is more than one “version” of a time sight, this method that I have been asking about relies on table XXV in the older versions of Bowditch. The method that I am familiar with uses the formula: cosP = (cosZD – sinLat * sin Dec) / (cos Lat * cos Dec). In the end, both methods accomplish the same thing, I was just wondering if this newer formula method would have superseded the older Bowditch method, however the Bowditch method with its tables would definately be easier if you never had a scientific calculator to comput the formula. Are there any other "versions" of time sights besides the two mentioned perviously (Bowditch tables & formula)? Also, with the implementation of time zones I assume that keeping local apparent time became a thing of the past on ships. The only time I hear it mentioned onboard now is when referencing local apparent noon for a noon sight.