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    Re: Plotting practice question
    From: Tony S
    Date: 1999 May 15, 22:24 EDT

    Rick:
    I think we're both on the same wavelength. It is clear that a new track
    begins with a confident true fix.
    What puzzles me is what you describe as "logged travel". Are you saying
    the ship's mechanical log, which might or might not be accurate, is
    significant?
    Tony
    Rick Emerson wrote:
    >
    > anthonys{at}XXX.XXX writes:
    >  > Rick-
    >  > Hmmm, well yes/no  :)  The resultant is the accumulation of all errors.
    >  > Since you started with a DR position, that even may be in question.
    >  > Right? Then there are other potential errors accumulated beyond set
    >  > and drift: ie, steering errors, leeway, minor compass errors, etc.
    >  > These are not really discretely identifiable or plottable. Therefor,
    >  > an accurate fix is truth and intermediate stuff can be discarded.
    >  > Programatically, all it can deal with is the track from start (DR) to
    >  > finish (Fix). Does the program accomodate "estimates" for other
    >  > variables? Did I understand your question correctly???  :)
    >
    > Er, not quite, although you do have the basic points (e.g., DR error
    > is cumulative) down.  I went back to Bowditch and in sections 703 and
    > 704 (pp 114-115) of the '95 edition it clearly says the track is
    > restarted with the fix.  It also says, and this is the answer to the
    > question I raised, nothing about counting the distance between the
    > last DR point and the fix.  As you suggest, information about the
    > overall errors can be inferred from the direction and magnitude of the
    > change, but it's not logged travel.
    >
    > Rick
    > S/V One With The Wind, Baba 35
    

       
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