Re: [Paddlewise] lift and efficiency

-----Original Message-----
From: K. Whilden <kwhilden_at_u.washington.edu>
To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net>
Date: Monday, July 27, 1998 12:57 AM
Subject: [Paddlewise] lift and efficiency


>Lets talk about efficiency for a moment.
>
>Loosely defined, efficiency means the ratio of power output over power
>input. Ealier, John Winters quoted some efficiency numbers, .92 for modern
>wind paddles, .86 for regular modern paddles. He didn't state the exact
>application of the these numbers, but I would hazard a guess that it means
>that for every 100 watts of paddler effort, 92 watts of are translated
>directly into forward motion of the boat (86% for regular paddles). The
>other 8 watts are lost due to turbulence, slippage of the paddle through
>the water, flexing of the paddle shaft, etc...

Missing from this list is energy loss in the paddler's body due to heat
generation and poor stroking.  I believe that this body loss is far more
significant than losses due to the paddle/water interaction.  Each body is a
machine that has an speed/force combination at which it is most efficient.

The only way to find the best combination is time trials, using a stopwatch
over a known distance.  These trials are not just for racers!  Try a long
narrow blade paddle and a low stroke and compare to a short fat blade with a
vertical stroke.  Try comparing the same blade and style at different
lengths.  You don't have to go all out to do these tests.  Use what seems to
you consistent effort.  The results may be surprising.  Your subjective
sense of which combination is best is not to be trusted without the
stopwatch.

Jerry

***************************************************************************
PaddleWise Paddling Mailing List
Submissions:     paddlewise_at_lists.intelenet.net
Subscriptions:   paddlewise-request_at_lists.intelenet.net
Website:         http://www.gasp-seakayak.net/paddlewise/
***************************************************************************