Re: [Paddlewise] Rudder redux

From: Nick Schade <nick_at_guillemot-kayaks.com>
Date: Mon, 2 Jul 2007 14:10:43 -0400
On Jul 2, 2007, at 1:07 PM, Craig Jungers wrote:

>
>
>> But you claimed Caffyn's data stands on its own.  Clearly it doesn't.
>
>
> Clearly it does. It's data. It's recorded. It's not opinion or  
> hearsay. It
> needs someone to go out and repeat it. It might bear further  
> analysis. But
> it doesn't need unjustified opinions.

My first car had manual steering. My new car has power steering. I  
got better gas mileage with my old car than I am now getting with my  
new one. (kind of sad)

Therefore: Manual steering is more fuel efficient for all cars.

Caffyn's data is undoubtedly accurate. That doesn't mean you can draw  
any generalized conclusions from it. There are a lot of variables  
that can effect the results. Lets assume the boats he used for each  
trip were identical except for the rudder. Lets further assume that  
he loaded the boat identically and the weather and ocean conditions  
were identical. We can also assume that on his second trip he had  
already done the trip once previously. This fact alone is enough to  
explain a large portion of his experience that the second trip was  
easier. I know that going places I've been before always seems easier  
and goes faster. I think the experience of doing a long expedition  
inevitably makes someone better at doing long expeditions. While that  
experience does not effect the kayak, it does effect the meat  
powering the kayak. I think it is typical that long distance  
travelers cover more ground at the end of a trip than they do at the  
beginning. I would be surprise if given identical conditions, and  
identical boats, the second trip was not faster. One feature of  
humans is they learn and get better at doing things.

But even if you could rule out every other variable in his experience  
and be absolutely sure that the only thing different between the two  
trips was the rudder and could thus conclude that the rudder is the  
sole source of any difference, this does not mean you can generalize  
the results to other boats in other conditions, paddle by other  
paddlers, paddling with different loads.  There may be something  
peculiar about the boat, paddler, or conditions that resulted in the  
rudder creating an increase in efficiency.

The boat he used may be particularly unbalanced, requiring an unusual  
amount of correction to maintain course. Mr. Caffyn may have some  
peculiarity in his paddling technique that a rudder overcomes. The  
conditions he paddled in may have been such that a rudder was  
especially beneficial.

There is a lot more to Caffyn's trips than the presence or lack of a  
rudder. While any data that comes out of the trip is interesting, it  
can not stand by itself because we don't know much about the  
circumstances that created the data.

There is more to the difference in mileage of my two cars than the  
presence or lack of power steering. No one would think to conclude  
that one man's experience with two different cars can be translated  
to apply to all cars with all people. More data is required be for  
you can conclude anything.

Nick



Nick Schade

Guillemot Kayaks
824 Thompson St
Glastonbury, CT 06033
USA
Ph/Fx: (860) 659-8847
http://www.guillemot-kayaks.com/
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Received on Mon Jul 02 2007 - 11:10:55 PDT

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