Re: [Paddlewise] multiple exposure photos of a paddle stro

From: Jerry F <gfoodma_at_earthlink.net>
Date: Fri, 1 May 2009 11:52:14 -0700
Matt wrote:
> A low stroke may be more relaxing for the paddler but because it is 
> further
> off the centerline of the kayak it turns the kayak more than a more 
> vertical
> stroke so is also less efficient in that respect. Of course, how the human
> feels and how the human can get the best leverage and exert the most force
> counts as well and argues against a vertical stroke pulled straight back 
> right
> next to the kayak.

It seems to me that there are three places where energy is lost: 
interaction between paddle blade and water, the paddlers body, and energy to 
overcome boat drag.  The energy required at a given speed to overcome drag 
is what it is, and nothing can be done except getting a lower drag boat.  I 
suspect that energy lost due to inefficiency in the stroke much exceeds 
energy lost at the blade/water interface.  I believe, for example, that the 
efficiency gained from a wing paddle accrues due to stroke geometry and the 
resulting body's efficiency in max energy extraction from torso rotation, 
and only secondarily from the paddle's grip on the water.  For long distance 
cruising much energy can be used up just raising arms each stroke.  From 
trying different length paddles with an easy turning boat (Mariner Express) 
I concluded that losses due to turning effect of a longer paddle are 
negligible.

I don't agree that the 'best leverage and exert the most force counts as 
well' is the relevant point.  It take a certain power level, not force, to 
drive the boat at a given speed.  Each paddler will have a power level 
determined by force, leverage and cadence that is most efficient for him, 
i.e., that uses the least power at the given speed.

Jerry 
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Received on Fri May 01 2009 - 11:52:11 PDT

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