NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2011 Jul 25, 23:01 -0700
Bruce,
At a height of eye of 6 ft. there will be no extra dip short corrections for a distant shore beyond 3 nautical miles or 18000 ft. It is best to work in nautical miles. I recommend using the 1981 Bowditch vol. 2 tables #22 to figure dip short and table #8 for the distance of the visible horizon. If you sit in a chair then your height of eye will be 4 ft so that a distant shore of 2.3 NM or more can be treated as a natural horizon (no dip short). The table you made up is a little off. 20,000ft (3.3 NM) would be treated as a natural horizon. I'm getting for 10,000ft. (1.7NM) -2.7' dip and for 5,000ft. (0.8NM) -4.6' dip by table.
Greg Rudzinski
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