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    Re: Cannot dispense with the assumed position at sea
    From: Doug Royer
    Date: 2004 Feb 19, 12:40 -0800

    -----Original Message-----
    From: Royer, Doug
    Sent: Thursday, February 19, 2004 12:18
    To: 'navigation-l@listserv.webkahuna.com'
    Subject: RE: Cannot dispense with the assumed position at sea
    All positions at sea may be called assumed positions!They are all where you
    were,not where you are.Errors or conditions while shooting the sight or
    reduceing the data may have you not where you believe you were.Nothing in
    real life is perfect.
    Perhaps I missunderstand what you are trying to convey.Perhaps it is a
    function of wording between what you call an assumed pos and my definition.
    For me an assumed pos or positions are what one uses in lue of a dr or ep
    pos when reduceing a round of sights.An AP is the position chosen to reduce
    the sight instead of the dr or ap pos.
    One choses the assumed pos to be the closest whole degree of Latitude of the
    dr or ep latitude.The longitude of the AP is chosen by useing the whole
    degree of longitude of the dr or ep,subsituteing the ' and " of the body's
    LHA for the " and " of the dr or ep longitude.One choses this assumed
    longitude to stay with in 30' of arc of the dr or ep longitude.
    You can then enter reduction tables or solve for the nav triangle to find
    the intercept and AZ thus finding the LOP or the fix if a round of sights
    were taken.
    One can also use the dr or ep pos to solve the nav triangle with out useing
    an AP.
    Am I not understanding what you wrote or is it a matter of definitions?
    A celestial EP will only be as good as the AP. The more one has to guess at
    the AP, then the less confident one can be about estimating where the vessel
    is on the celestial LOP.

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