Subject: Re: [baidarka] baidarka speeds
From: Peter Chopelas (pac@premier1.net)
Date: Tue Sep 28 2004 - 22:40:30 EDT
> To me, most of the Euro paddles are based on "catch". They want to stop
> the water, provide a solid anchor against which you pull yourself
> forward. They are best for a strong European-frame paddler. The
> Greenland and Aleut paddles are based more on "flow". They want to use
> their design shape to direct the flow of the water so as to provide a
> moving resistance against which the paddler pulls. This moving
> resistance makes the traditional paddles easier on the body, more
> fluid, part of the natural flow of the body. Traditional paddles don't
> "catch" the water, they flow through the water.
Jim,
I have news for you, the thrust on all paddles is generated the same way, by
altering the flow of the water around the blade. In order to get any
thrust, or "resistance" from a fluid, you have to accelerate the fluid over
the surface. Although not obvious, the "feel" of the paddle's resistance in
the water is caused by accelerating (or curving or "bending") the fluid
around and over the surface. Clearly since any fluid in not a solid, there
is nothing to "push" against, and nothing to "catch". All of the action in
either paddle design is caused by accelerating the fluid over the blade.
They may accomplish this in different ways, but they ultimately accomplish
the same thing.
The shape and aspect ratio of the blade may cause large differences in how
the reaction feels at the shaft, but both low aspect ratio Euro paddles, and
high aspect ratio native paddles generate thrust the same way. Low aspect
ratio paddles are more stall resistant and depend often on large trapped
vortexes on the low pressure side to curve or accelerate the water, and high
aspect ratio paddles tend to work by curving or accelerating the water by
"potential flow". But both generate thrust by accelerating the water over
the surface. It is not drag or resistance that you are using to generate
the forward motion, if this was true a tennis racket would make a better
paddle than a smooth curved blade.
Peter
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