NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Plotting 3-Body fixes
From: Jim Thompson
Date: 2003 Sep 3, 06:45 -0300
From: Jim Thompson
Date: 2003 Sep 3, 06:45 -0300
This is a "newbie" question. I am learning celestial navigation. What is the convention for plotting 3-body fixes taken within a few minutes of each other? Say I take 3 sights on 3 stars, on a moving vessel, all within a span of 15 minutes. Method A: 1. Work out DR positions for each of the sights (L, Lo). 2. Use the L and Lo for each sight's DR to work out the intercept, azimuth and LOP for that sight. 3. Advance the LOPs for the first two sights to the last DR to draw the cocked hat fix estimate. Method B: But the Canadian Power and Sail Squadrons' course manual implies a different method, although I am reading between the lines to operationalize what they wrote: 1. Work out DR positions for each of the sights (L, Lo). 2. Use the L and Lo for each sight's DR to work out the intercept, azimuth and LOP for that sight. 3. Simply plot the LOPs for for all 3 sights from the last DR to draw the cocked hat fix estimate (without formally advancing the 2 earlier LOPs). Jim Thompson jim2@jimthompson.net Outgoing mail scanned by Norton Antivirus -----------------------------------------