Re: [Paddlewise] Paddling efficency

David Carlson wrote:
> 
...
> My discussion was considering only  how much work is being done by the
> paddle vs. how much work goes to propelling the boat.  The paddle puts
> out exactly as much power as was put into it. There is no significant
> friction or other energy dissipating mechanism internal to the
> paddle.  So the difference between effort (paddler output) and paddle
> output is nil.  The only effort I am neglecting to consider is
> physiological, and internal to the paddler.

You're making two contradictory claims. One, that power output is equal
to power input for all paddles. Two, that some paddles are more
efficient than others. Since efficiency is a measure of the ratio
between power input and output, you've sort of disproved your claim via
a classic reductio argument.

If in fact some paddles are indeed more efficient than others- and that
is not a claim I have ever made- then you have consider how much useful
work is done by the paddle, and how much just goes into heating the
water. That's why I stressed boat speed as a measure of useful work
done. Since we're not paddling in a calorimeter our only measure of
power output is boat speed.

So while the energy coming out of the paddle is equal to that going in,
minus some negligible hysteresis losses, that's still not the entire
story.

But we're really still arguing two separate issues. My position was that
a human is more efficient at producing lower output over a long period
of time than at producing high output for a short time. Biomechanical
studies bear that out, and that is why narrow paddles tend to be better
for distance paddling.

-- mike
---------------------------------------------------------------
Michael Edelman   mje_at_spamcop.net
http://www.foldingkayaks.org (nomadics)
http://www.findascope.com (choosing a telescope)
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