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    Re: Dr
    From: Dan Hogan
    Date: 1999 Feb 22, 18:24 EST

    Millard:
    > Silicon Sea,
    [Snip problem stuff Q2]
    >   I must admit that these problem have been a great learning experience
    >   for me.  If one uses the current to get the DR is it really DR or estimate
    > position (EP).  Bowditch - Dead reckoning (DR) determines position by
    > advancing a known position for courses and distances. A position so
    > determined is called a dead reckoning (DR) position.  It is generally
    > accepted that only course and speed determine the DR position.  Correcting
    > DR position for Leeway, current effects and steering error results in an
    > estimated position (EP)
    My fault. We agreed during the legs from Maldives to Sydney to call DR=
    no current and EP=current. Will change my terminology. I'm having a
    hard time with this since in all my sailing all I used the term DR for
    everything.
    [Snip]
    > To get DR on the Celesticomp V it asks for Departure Lat & Lon, Steered,
    > Speed, Var&Dev and Turn Point time.  I guess the "Steered" always did
    > drive me little crazy in the DR program because there is a program that is
    > called STEER/CUR which give one the Course to Steer if one has Desired
    > Course (TC) Var&Dev, Log Speed, Current Dir, and Current Velocity.  So if
    > I use the "Steered" Compass course  from the STEER/CUR in my DR program I
    > actually get EP not DR.
     The problem is that Bowditch has been made "politically correct", a
    lot of earlier navigation books, texts, and methods use the earlier
    definitions, I.e. Course-to-steer, Course Made Good.etc.
    In my hard drive double crash of '98 I lost most of my tips and hint
    for Silicon Sea. If anyone has the definitions list please post it.
    Any how from now on:
            DR = position based on distance = time x speed
            EP = DR plus the correction for current.
    Dan Hogan WA6PBY
    dhhogan{at}XXX.XXX
    Catalina 27 "GACHA"
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