A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John Karl
Date: 2015 Apr 27, 12:17 -0700
This is an old topic, but I guess it's time to address it again. The conventional running fix, of advancing an LOP parallel to itself to the DR position at the time of a new LOP, is complete nonsense (except maybe in very special cases). Usually we're considering a new CN LOP after a DR run that has more uncertainty than the new CN LOP. (Otherwise, why bother with the new LOP?? And BTW, a new LOP of ANY orientation with better acccuacy than the DR improves the DR.)
The traditional running fix assumes the DR track perpendicular to LOP1 (the first LOP) is completely accurate, while the DR track component parallel to LOP1 is completely without any information. See the figure below.
Now I've asked this question before (in post g11116; in my CN book, problem 3.10; and in "The Nonsensical Running FIx," Ocean Navigator, p51, Nov/Dec 2010:
How can the orientation of the advanced LOP have anthing, whatsoever, to do with the error in the DR track?? No one has yet offered an answer.
Here's to the "fixed" traditions of CN,