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    Re: Leg 56 Question # 3
    From: Bill Murdoch
    Date: 1999 Jul 19, 7:40 PM

    In a message dated 7/17/99 1:31:35 PM EST, dhhogan@NAV.CNCHOST.COM writes:
    > So you use only the data you can rely on. Time/speed and distance. Which is
    why I prefer to DR using a distance log rather than boat speed.
    I agree and do the same, but then why do the USPS and most texts always
    multiply time and average speed to get the distance run?  I would have
    thought it to be better to use the logged distance letting the instrument
    find the intergrated product rather than relying on me to guess the average
    of the speed readings for an hour.
    It is also the way I have calibrated my knotmeter.  I run a measured distance
    under power in still water, compare the distance by log to the distance by
    chart, and figure the error as a percent.  Then holding the engine speed
    constant, I turn the calibration screw to raise or lower the speed by the
    percent error.  It seems simple to me and seems to work.
    Bill Murdoch

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