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Subject: Re: Leg 56 Question # 3
From: Bill Murdoch (WSMurdoch@XXX.XXX)
Date: Mon Jul 19 1999 - 21:39:45 EDT
In a message dated 7/17/99 1:31:35 PM EST, dhhogan@XXX.XXX 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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