NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sumner's Line (Navigation question)
From: Bill B
Date: 2006 Feb 15, 14:28 -0500
From: Bill B
Date: 2006 Feb 15, 14:28 -0500
Gary wrote "Capt. Sumner had to work the time sight twice, doing the math two times which was difficult in the days before inspection tables and computers. Marc De St. Hilaire's contribution ...People should consider using this new (old) method today." Yes, the old becomes new again. In her book "Practical Celestial Navigation" Susan Howell notes a calculator method of determining two points to establish and LOP. She attribute it to the USNO Circular #155, Almanac for Computers, 1977, 1 October 1976. Longitude = GHA Body +/- cos^-1 (sin Ho - (Sin L sin d)) / (cos L cos d) which uses GHA instead of using time and Eqn of time. Bill
