[Paddlewise] Odometer for a kayak

From: Ken Cooperstein <cprstnc1_at_optonline.net>
Date: Thu, 24 Dec 1998 10:58:12 -0500
I received two inquiries concerning my post about the N-K SpeedCoach:

(1) Please elaborate on speed thru the water vs. speed over the bottom.

Answer.  The difference between the two speeds is caused by current and
leeway.  The impeller only sees how fast water is moving past it; it has
no idea how fast current might be running and does not measure the
transverse speed.  That is, you could be paddling at 2 knots with a 3
knot current while the wind is blowing you sideways at one knot.  You
are really moving at something like 5.1 knots, but the device will only
register 2 knots.

(2) What are the spring and drag devices like?

Answer.  They all operate on this principle:  If you tie a string to a
say a steel nut and drop the nut and string over the side (holding the
other end of the string), the pull on the string will increase with boat
speed (I think with the square of the speed).  The item with which I am
most familiar (having one) is the Knotstick.  See:
http://www.knotstick.com/
$33.95 at Defender Inds. (1-800-628-8225).  This item will probably
create around 4-5 oz. of drag at kayak speeds, which may be too high.
There is no reason why it couldn't be scaled way down to give 1-2 oz.
and still work.

Ken Cooperstein


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Received on Thu Dec 24 1998 - 07:59:15 PST

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