Re: [Paddlewise] High Aspect Ratio Paddles

On 10 Jun 2003 at 18:56, Peter Treby wrote:

> Thanks to Peter Chopelas for showing that high aspect ratio paddles
> are more efficient.

As Bob points out, Peter's analysis is based on some assumptions that 
are not valid and we've argued with him about it several times (this 
is the third or fourth time he's posted it here or on Baidarka), 
however, he takes it personally and will not discuss it.  Another 
example of the flaws in it is the horsepower requirements he 
estimates for a Euro paddler; 0.4hp.  I've pointed out that a normal 
human being is incapable of this level of output.  When I suggested a 
lower value being appropriate, he said _my_ estimate was too high.  
However, he still hasn't corrected his analysis to reflect what he 
admits is an unrealistic value.

I've said it before and I'll say it again:  You cannot prove a 
physical phenomena with mathematics.  You can prove a mathematical 
concept with mathematics.  A mathematical model of a physical process 
must be demonstrated to be reasonable by experiments and those 
experiments have not been done by Peter.  Hence his "proof" stands as 
nothing but mathematical fiddling.

Another issue is that he will not resolve his definition of 
efficiency with that of everyone else.  Those who have done the 
experiments know that a _low_ aspect ratio paddle is more efficient 
(see "The Shape Of The Canoe" by John Winters).  

Those of us who have paddled with various paddles know from 
experience that the high aspect ratio paddles tend to be lower in 
efficiency.  As I said in a recent post, when paddling a long day 
with my Greenland style paddle, my muscles get sore but my joints 
don't.  The lower efficiency means I do more work with less 
accumulated stress.

The basic concept in generating paddling forces efficiently is to 
move a lot of water at a low velocity.  Greenland paddles don't do 
that and are therefore not as efficient as short, fat Euro paddles.

Mike

***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************