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Subject: Re: DR vs EP vs MPP vs Fix vs Running fix
From: Bill Allan (ballan@XXX.XXX)
Date: Thu Feb 07 2002 - 22:26:59 EST
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" <jared.sherman@XXX.XXX>
To: <NAVIGATION-L@XXX.XXX>
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.
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