NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Francis Upchurch
Date: 2013 Sep 2, 23:58 -0700
Hello Navlist experts. I've been doing Cnav for years and joined the lunatics 2 years ago, but this is my first posting. Questions probably directed at Frank Reed,John Karl, Gary La-Pook,but any help appreciated.
1)Frank,I found this from you --["remarkable "miracle" that applies to lunars measured around 90 degrees. Also, the amazingly easy method for clearing lunars requiring almost no trigonometry that follows from this fact and was completely over-looked in the period when lunars were practiced at sea."]-- Frank,would you mind expalaining this to me, a non mathematician?
2)I like to use the Bygrave slide rule for LOPs. Does anyone know how I could use it for lunar clearance as described in Karl's book page 89? I can use it for "great circle distances" and maybe I can adapt the nav triangle for lunars?
3)Frank, I've been studying the use of lunars in Cook's Endeavour voyage. His journals say he had 1767-8 nautical almanacs to help with the "short," method of clearance. However, his journals mention lunars taken on the return trip, after Greens's death, in 1771,3 years later. Did he have to do the Maskelyne "Easy" 4 hour method then? has anyone tried to do these?
Thanks in anticipation for any help.
Francis Upchurch
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