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From: (no name) (no email)
Date: Tue Apr 10 2001 - 22:20:44 EDT
In a message dated 04/03/2001 11:49:38 AM Eastern Daylight Time,
writes:
>
> I tried something similar with a half filled water bottle (simulated log)
on
> the end of a string. Using the idea that 1 nautical mile is about 1800
> meters, I tied knots in the string every 3 meters. Then I let the bottle
go
> and started my stopwatch. I counted how many knots passed through my
> fingers during 6 seconds (3meters / 6seconds = 1 knot speed). If 5 knots
> passed in 6 seconds I was doing 5 x 3meter / 6sec x 3600sec/hr = 9km/hr = 5
> knots
I presume everyone knows that this technique is how "knot" as nautical speed
got its name.
The original "knot meter" is called a Chip Log and consists of a thin knotted
rope on a reel with handles on the reel shaft to allow it to turn freely.
The "chip" is a piece of wood, about 3/8" thick, a quarter circle pie shaped
piece (from an about a 16" pie) with a lead weight attached at the curved
edge to keep it vertical in the water. A three string bridle attaches the
knotted rope to the chip but two of the strings are attached to pegs that fit
into holes on the chip so that a good yank on the rope pulls them out to
allow the chip to be hauled easily back aboard.
The chip is cast and a "hour" glass is turned over. The chip floats curved
side down vertically in the water and the knotted rope reels out. The knots
are counted until the glass runs out of sand. This is the speed of the
vessel in knots. The rope is yanked, freeing two of the three bridle
strings, and the chip is reeled back aboard.
The time of the glass and spacing of the knots is up to the maker.
A trip to a good maritime museum might be beneficial.
Norm
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