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    Re: The Noon Fix
    From: Gary LaPook
    Date: 2009 Apr 11, 15:15 -0700

    You wrote:
    
    "I'm a sailor and course changes are not trivial, and usually
    dependent on
     the wind. I've never worked for a captain who would change his course
    for
    an hour for the convenience of the navigator. As a backup to GPS, the
     method would be used  in emergency conditions, when arbitrary course
     changes would not be prudent."
    
    I'm a sailor too and except for four points on either side of the wind
    you can usually choose any course you want. I disagree with your
    statement that in an "emergency" it would not be prudent to change
    course. We are not talking about a normal "emergency," hurricane
    coming, hull holed, etc., but only a "navigation emergency" or
    inconvenience. So why not? You should especially do anything necessary
    to navigate in this circumstance including changing course, selecting
    a different destination, heaving to around noon etc. I suspect the
    captain would change course for the navigator in such a circumstance
    although he may lower his opinion of said navigator.
    
    Calculating an LOP to me is trivial so I overlooked your point that
    your method doesn't require the calculation of LOPs and so would be
    easier for one who doesn't know celestial.
    
    But he can cheat too and make it easier for himself. Just heave to for
    an hour and have lunch and take the two sights and use your method to
    find the noon fix.
    
    gl
    On Apr 11, 11:17�pm, James N Wilson  wrote:
    > Gary:
    >
    > You wrote:
    >
    > Why not just cheat?
    >
    > For the short period between the two observations simply change your
    > course to straight east of �west, that eliminates the problem of vessel
    > movement. Even better, adjust the course slightly north or south of
    > east or west to create a vector north or south movement to compensate
    > for the change in declination of the sun.
    >
    > I'm a sailor and course changes are not trivial, and usually dependent on
    > the wind. I've never worked for a captain who would change his course for
    > an hour for the convenience of the navigator. As a backup to GPS, the
    > method would be used �in emergency conditions, when arbitrary course
    > changes would not be prudent.
    >
    > And:
    >
    > That said, I don't see any advantage over the traditional method of
    > advancing the morning sun line to cross the afternoon sun line.
    >
    > The advantage over calculating lines of position is that there is no
    > calculating. The arithmetic involved is only addition and subtraction. I
    > note in the referenced paper that "Since plotting runs of sights is
    > always recommended, no extra work is involved there, and the few
    > computations are significantly less than reducing a pair of sights and
    > plotting them to get a fix." And now there are no computations at all.
    >
    > Thanks for your interest. In my classes, I encourage questions, since
    > others may benefit. Your opinion may well be shared.
    >
    > Jim Wilson
    > ____________________________________________________________
     
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