A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Stan K
Date: 2017 Mar 20, 14:55 -0400
The way I was taught, your DR position is determined strictly by planned course, speed, and time elapsed, to determine estimate distance traveled and position. Current/leeway is not considered in determining a DR position, so if you do get a good fix by some method, you can then compare your DR position to your fix and determine the effects of current/leeway. You reduce a single sight from your DR position, draw the LOP on your DR plot, then draw a line from your DR position perpendicular to the LOP. The point where the line intersects the LOP is your EP, a position more probable than your DR position, but not as good as a fix. However, once the current/leeway is known (or at least estimated), the EP can be adjusted accordingly.