A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John Brown
Date: 2015 Nov 25, 02:14 -0800
For distances at sailing vessel speeds use the polar to rectangular function on a calculator and divide the departure by the cosine of the mean latitude to get dlon.
Using the mean latitude is not strictly accurate, but fine for all practical purposes when updating a DR or reversing the process to calculate course and distance run.