Re: [Paddlewise] Paddling efficency

At 2:53 PM -0400 5/16/01, Michael Edelman wrote:
>Nick writes:
>
>   - Everything else being equal the paddle with the largest blade area
>will be the most efficient.
>   - Everything else being equal the lightest paddle will be the most
>efficient.
>   - Everything else being equal the fastest cadence will be the most
>efficient.
>
>... but I think I have to take issue with those claims. Nick earlier
>made a point of distinguishing paddle efficiency from human
>biomechanical efficiency, but he's confusing the two above. Weight and
>cadence only come into the equation when you put a human on the end of
>the paddle. Paddles don't have cadence. Humans do.
>
>So yes, the HUMAN with the lighter paddle will be more efficient, simply
>because he doesn't have to expend energy moving that mass back and
>forth.
>
>Will the human with the higher cadence be more efficient? Not
>necessarily. If we limit ourselves to the typical range of paddles, the
>human with the higher cadence will be operating more efficiently, but he
>or she will only be paddling more efficiently if the paddle is designed
>to take advantage of that. If I'm doing 60 strokes per minute with a big
>whitewater paddle and you're doing 120, you're generating a lot more
>power, but you're no more efficient than I am. You may be less
>efficient.
>
>If I'm using a Greenland paddle at 120 strokes and you're using a wider
>paddle at 60 and we're keeping pace, and all other factors are equal,
>then I'm probably more efficient.
>
>As for blade area: Not true. A larger paddle will displace a larger
>volume of water when swept over a given arc, but that's just geometry.
>Efficiency requires comparing power in to power out. While larger blades
>can generate more power, that doesn't mean they're more efficient. They
>also require more driving force, and the payback is not necessarily
>greater per unit of input. Generally, with humans, as you increase power
>output you get diminishing returns in terms of effort per energy output.

I did say "all other things being equal". Which, as someone pointed 
out, is a bit of a cop out, but is the only way to understand what is 
going on. If you have a higher cadence but use a different size 
paddle than two things are different and the comparison is more 
complicated. I believe the higher cadence is both physiologically 
(within limits) and physically more efficient. Of course that assumes 
_everything_ else stays the same.

And all other things being equal, a larger paddle creates more lift 
when used as a wing or more drag when used as a parachute, so 
everything else being equal, it is more efficient. Unfortunately, 
something else always changes, so it is hard to make a realistic 
comparison.

Since changing one parameter always changes another, it is 
theoretical possible to optimize all the parameters to get the "best" 
paddle. And since there are physiological limits to what the human 
body can perform, the design that is physically/mechanically the most 
efficient, may not end up being the most efficient when used within 
those limits. And since everyone has different physiological 
capabilities, the most efficient paddle design will be different for 
everyone. I would be very surprised if the a 
native/greenland/inuit/aleut/traditional style paddle didn't turn out 
to be the one of the most efficient for some people in some 
situations. I'm sure that there are probably multiple "best" designs 
for a given person in given conditions because there are so many 
parameters that can be changed
-- 
Nick Schade
Guillemot Kayaks
824 Thompson St
Glastonbury, CT 06033
(860) 659-8847
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