Re: [Paddlewise] Apology for post about paddle efficiency

"Peter A. Chopelas" wrote:
} Subject: [Paddlewise] Apology for post about paddle efficiency
> 
> This background is necessary to demonstrate that in order to measure 
> efficiency, the way I was using it, you must have three different 
> measurements:  a unit of force, a unit of time, AND a unit of length.  To 
> say the paddle that moves slower with the same force (a unit of time and a 
> unit of force only) is more efficient is not possible, you do not have 
> enough information.  

"slower" to me means velocity, not time.

A unit of velocity is a combined unit of length and time.  So "slower
with the same force" is a unit of *velocity*, and a unit of force,
which is a unit of power.  Try dimensional analysis for a moment.

> The whole idea of "slippage" when applying a force against a fluid is as 
> equally meaningless, especially when talking about efficiency the way I 
> meant it.  If you define slippage as the amount of distance the paddle move 
> backward from a fixed point relative to the water surface during a stroke, 
> you end up with a lineal distance measurement only.

No, it's a velocity.  How *fast* the paddle slips backward.  And that
mkes it power.

>  Not enough information 
> to determine efficiency at all.  I suppose you could redefine it as 
> "slippage efficiency" and use that as a criteria.  But it would not be 
> related to power consumption at all.  By this definition than the largest 
> paddle you can get would have the least slippage, and be the most 
> "slippage" efficient.  But clearly this is not true with regards to power 
> consumption.

This IS true.  Don't just say "clearly this is not true".  Since
you're clearly not interested in hearing this from me, try reviewing
this web page:

http://www-atm.atm.ox.ac.uk/rowing/basics.html#section3

> Slippage is a nonsensical way to even think of the way a paddle works 
> anyway.  You can not apply a force against a fluid without "slippage", it 
> would not be a fluid by definition.  

Of course you always have slippage, but that does not mean you can't
minimize it.


> way, otherwise you can not communicate.  It is especially unfortunate that 
> recent trends have been to use fancy words improperly because it makes 
> speech or prose appear more sophisticated.  It is one of my pet peeves, and 
> really demonstrates lack of language skills, not sophistication.  But it 
> also leads to many unknowingly using words like "efficiency", "power", and 
> "force" in inaccurate ways, and not to understand what these words really 
> mean.

A remarkable statement from someone who claims that "slower" implies
a unit of time, with no length component.



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