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Subject: Re: Leg 56 Question # 3
From: Lu Abel (lu.abel@XXX.XXX)
Date: Mon Jul 19 1999 - 23:45:22 EDT
At 09:39 PM 7/19/99 EDT, Bill Murdoch wrote:
>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.
I believe this is an example of the USPS and many of the standard texts
either being way behind the times, contemporary, or just not mentioning
another way to solve a problem.
Way behind - The USPS courses, for example, discuss obtaining speed vs RPM
curves for one's boat. Good 1920's practice when electronic knotmeters
didn't exist. Maybe actually carried into the 1950s by the Navy. Has
anyone on the list actually made such a curve?
Contemporary - because most of us have knotmeters
Not mentioning - several times I've seen reference to "just trail a Walker
log" as a much better way of getting DR distance than 60D=ST, but this
technique doesn't seem to have made it into texts and USPS courses.
Pragmatically, I wonder how many people still trail Walker logs? I know
it's against the spirit of this list, but I feel obliged to point out one
can buy several GPS units for the price of a Walker.
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