NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robin Stuart
Date: 2017 Feb 5, 07:11 -0800
Geoffrey,
The quoted incorrect solutions (Zevering 2006, Metcalf 1991) introduced schemes for advancing an initial circle of position (CoP) on a sphere with the idea that they could then use standard double altitude methods to get the fix. It was assumed that an advanced CoP is still a circle but it's not. Hence the idea of getting a fix as the intersection of 2 circles just doesn't fly. There was quite a bit of discussion about this on Navlist in 2006 and again in 2010 and I had collected some of the links here along some some illustrations of the distortions that an advanced CoP undergoes.
The solution is to realize that the problem of the running fix on the sphere can be straightforwardly solved without ever advancing a CoP.
Regards,
Robin Stuart
