Re: [Paddlewise] Rudders/ frequency

Bob Washburn wrote:
> 
> For relevance, what percentage of a "good paddler's" energy goes into
> maintaining direction?  It would seem to be over 10% for most paddlers
> under most conditions.

This is an excellent question. In my experience, however, it seems as
though it is more like 3 to 5 percent--certainly far less than 10
percent. But this is based on a subjective judgement, and it is very
much dependent on the boat being paddled. I will be able to do somewhat
more objective measurements once I get my Differential GPS system
operational. (Is that John I hear groaning?) DGPS allows very precise
measurements of speed. I can try to maintain constant effort with and
without a rudder deployed in windy conditions, and measure the
difference in speed. I would hypothesize that I will make better speed
without the rudder. Of course the results could always be challenged on
the grounds that I receive a psychological boost by paddling without the
rudder. It is exceedingly difficult to run a test of this type with
"airtight" controls.   
 
> The test for the 10% could also have significant variance.    If the 10%
> was measured with the  rudder dead center and the boat pulled straight, the
> drag would be significantly different when being used to correct for
> crosswind/current.

I agree. I would guess that the typical flat-slab rudder adds more than
10% drag when held at an angle. BTW, where are the aeronautical
engineers when you need them? Didn't George Gronseth help to design the
rudder for the Boeing 767? I'm sure that he has something to say on this
subject. (BIG grin.) 

Dan Hagen
Bellingham, Washington
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