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    Going overboard on decimals
    From: Paul Hirose
    Date: 1999 Jul 24, 1:34 PM

    I hope everyone realizes that after Silicon Sea runs 3 days without a
    fix, including 2 days of severe storm, the tenths of minutes from a
    digitally calculated DR are pure noise.  Yes, you can copy the digits
    off the screen, but they are garbage because the inputs to the problem
    are not known with enough accuracy.
    Let's assume a day's run is 240 miles, more or less.  If average speed
    is off by 1%, that's 2.4 miles per day.  If course made good is off by
    1 degree, that's 4.2 miles per day.  Imagine how much worse this gets
    when you're being beaten up by a storm.
    I reported my results to only 1', and even that was overkill.
    Also, there's no reason to worry about seconds of time when dead
    reckoning on the high seas.  In this case, it's not that you can't
    measure time that accurately.  The problem is that uncertainties in
    the other parts of the DR equation - time and distance - are great
    enough to swamp any attempt to figure to the second.

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