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    Re: Spherical earth model vs. ellipsoid
    From: Dan Hogan
    Date: 1999 Mar 12, 11:47 AM

    The errors one will get from using celestial navigation at sea. will be
    not from any mathematical equations. But from a navigator that is
    "green-around-the gills" after 3-4 days of storm on a small boat
    bouncing on a rolling ocean. Toss in a hazy sky and uncertain DR and
    you have it.
    As the textbooks say. The mid-shipman makes a precise mark on the chart
    and says, "We are here.". the Fistmate draws a small circle and says,
    "About here.". The Captain comes in, slaps a spread out hand down and
    says. "We are someplace around here."
    On a small boat, making 5-8 knots, a daily Noon sight becomes just
    about right. Also, living on a boat for days on end that is doing much
    over 5.5 Knots gets to be downright miserable.
    So good seamanship dictates that a good lookout, a consistent DR and
    periodic position fixes be mixed with common sense.
    So if you get a cocked hat of about six miles, you are someplace around
    Dan Hogan WA6PBY
    Catalina 27 "GACHA"
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