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    Re: Fix Maximum Probability Positions
    From: Hewitt Schlereth
    Date: 2013 Mar 25, 19:57 -0700

    Yeah well, as I suspected from the beginning, this is where we part company. I 
    prefer to base the DR solely on two things - course and distance - because 
    they are underpinned by instruments - course by the compass, distance by the 
    I don't take into account factors like leeway, currents, sea state, etc till I 
    have an LOP. Then and only then, do I judge whether those other factors 
    reasonably account for the gap between DR and LOP. 
    Sent from my iPad
    On Mar 25, 2013, at 7:02 PM, "John Karl"  wrote:
    > Hewitt,
    > As I said it's the best estimate of the the track over ground, which 
    includes all factors that the navigator has available, or cares to use -- 
    course steered, distance logged, currents set & drift, leeway....
    > Greg,
    > OK, great.  Then you've used the EPRF that I've been discussing, middle 
    figure in my post 23074.  So then you used that same offset to east to plot 
    the 1100/0900 sun line RFIX.  Right?
    > If so, then this particular traditional running fix gives good agreement 
    between the estimated-track made-good and the updated LOP.  The estimated 
    position running fix (EPRF) would give the same result in this case.   (They 
    would also agree when the two LOPs are are right angles.)  So I don't get the 
    point.  Are you showing how well the EPRF works?? 
    > It's when there's a disagreement that the TRF fails and the EPRF gives 
    superior results.  Check the 2nd and 3rd figures in my 23074 post. 
    > JK
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