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Subject: Re: Taffrail log and an alternative
From: Trevor J. Kenchington (Gadus@XXX.XXX)
Date: Sat Jun 22 2002 - 09:41:48 EDT
Many thanks to Bill Noyce and Arthur Pearson for their suggested
solutions to the non-electronic log problem. I'd still like an
instrument that would record distance run rather than instantaneous
speed, without needing batteries or an LCD. Still, I might have to force
myself to compromise on one or the other feature!
As to Arthur's suggestion:
> For bay crossings in the fog of Maine and Nova Scotia, a simple 30 foot
> chip log allows one to measure speed often enough and accurately enough
> to keep an accurate DR for several hours. Simply tie a bit of wood
> (weighted on one edge to be traditional and to minimize wind drift) on a
> length of light line, drop the chip overboard and time the number of
> seconds it takes for 30 feet of line to run out. Divide 18 by the
> number of seconds to get nautical miles per hour, so 6 seconds indicates
> 3 knots. I measure speed and plot a DR every 15 minutes. Any inaccuracy
> in speed measurement is less important that whatever allowance one makes
> for current and lee way. This is all I have had on dozens of trips
> Downeast and back in Maine and combined with a good ear and a good nose
> you should be fine (keep the engine off so you can hear surf, gulls,
> barking dogs, etc.).
Heaving a chip log is an attractive alternative but a bit awkward if
single-handed or with a crew that does not share a passion for such
eccentricities. If reduced to that level of technology, why not go one
step further and use a Dutchman's log?
Trevor Kenchington
-- Trevor J. Kenchington PhD Gadus@XXX.XXX Gadus Associates, Office(902) 889-9250 R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251 Nova Scotia B0J 2L0, CANADA Home (902) 889-3555Science Serving the Fisheries http://home.istar.ca/~gadus
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