NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Bossert
Date: 2025 Nov 21, 11:09 -0800
There was a recent discussion about whether a DR (Lat and Long) of each sight should be used to compute a fix from three bodies sighted on a moving vessel over 20 minutes. Let's say a sailboat moving 7-8 knots in a consistent direction. One proposal is that DR of each sight is NOT needed. Graph a Circle of Position purely based on Hs converted to Ho only. Your three COP plot shows a triangle. Your fix is inside the triangle. On the other hand, another person said you need to reduce the sight considering DR of the vessel when each sight was sighted. And advance the Line of Position of Sight 1 to Sight 3 (distance and direction), Sight 2 to Sight 3. And the fix is the intersection of the 3rd sight's LOP and the sight 1 and 2 advanced lines of positions.
What is considered good practice for three body fixes happening during twilight?
Thanks!
