NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: DR vs EP vs MPP vs Fix vs Running fix
From: Bill Allan
Date: 2002 Feb 7, 22:26 -0500
From: Bill Allan
Date: 2002 Feb 7, 22:26 -0500
I haven't been faced with the choice of how I would "reckon" with known errors such as Gulf Stream currents etc. My boating has always been on the Great Lakes (no tides, no Gulf Stream etc. etc). I would probably still use traditional DR techniques (since I know what it represents) and use more than the usual amount of sun lines to get lots of rfixes if I was in doubt about the suspected strength of the current. At 6 knots I can't see much of a problem. ----- Original Message ----- From: "Jared Sherman"To: Sent: Thursday, February 07, 2002 6:36 PM Subject: Re: DR vs EP vs MPP vs Fix vs Running fix > Chuck - and all- > <"The DR position is only an approximate position because it does not allow > for the effect of leeway, current, > > Is there anyone here who would "reckon" their position without attemping to factor in ALL known effects? If one is plotting a DR position while crossing the Gulf Stream, even without knowing the current, is there anyone who would not indicate *some* offset as a best guess of the current, since they approximate current direction and speed are almost certain to exist to some extent? > > I ask this as a poll, not as an arguement. My understanding of DR, the good Mr. Bowditch aside, was that a navigator placed EVERYTHING he could into the DR position and that it was supposed to include all "guestimates" of where you actually were, not just ignoring the ones you couldn't specify to five decimal places.