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From: John Winters <jdwinters_at_eastlink.ca>
subject: [Paddlewise] Rudders redux
Date: Mon, 02 Jul 2007 17:41:44 -0300
> John asked about extra drag from having the kayak leaned to turn it or
> correct a course. (SNIP)

I certainly don't have any data and that is why I would never make any 
claims about it. Tank researchers would tow the boats heeled as well as 
upright like they do sailboats and that would give some insight. They would 
also tow the boats at different leeway angles ot see if the boats made more 
or less leeway and under what circumstances. Matt could run the numbers 
through the Taylor Standard series and that might be interesting. Sea 
Kayaker could run them with KAPER although I would have little faith in the 
results if the heeled shapes fell outside the database used to create KAPER. 
(would it not be interesting if it were discovered that some boats have less 
resistance when heeled than when upright) Those people that wrote the book 
that Craig says has no application could do oxygen take-up tests while a 
person rolls a boat and then compare it to the effort required to steer the 
boat with a rudder. Sports biomechanics folks could could study muscle usage 
etc. to determine if one method is harder on the body than the other. 
Pooling all this data would probably lead to a lot of insight and lead us 
away from speculation and opinion.

Matt also wrote;

> Oh, I guess that is just poor design again so we shouldn't consider it a
> problem with rudders in general. (SNIP)

Matt, that is beneath you.

Craig wrote;


> Caffyn recorded a nearly-33% increase in daily mileage with a rudder
> compared to no rudder.

This is really interesting. Matt reports that the rudder adds 10% additional 
drag.

Who is right? Matt and Craig, how do you explain this? Are both of you 
right?

I wonder what kind of statement Caffyn would make if he had paddled a 
Mariner XL around Australia. :-)

Cheers

John Winters
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From: Craig Jungers <crjungers_at_gmail.com>
subject: Re: [Paddlewise] Rudders redux
Date: Mon, 2 Jul 2007 19:18:53 -0700
On 7/2/07, John Winters <jdwinters_at_eastlink.ca> wrote:

> > Caffyn recorded a nearly-33% increase in daily mileage with a rudder
> > compared to no rudder.
>
> This is really interesting. Matt reports that the rudder adds 10%
> additional
> drag.
>
> Who is right? Matt and Craig, how do you explain this? Are both of you
> right?


Well it's certainly possible for both of these to be right. The towed tests
simply measured drag; more or less competently depending upon who is to be
believed.

Caffyn's data simply measured miles paddled in the same boat with a rudder
compared to miles paddled in the same boat without a rudder on a per-day
basis. Of course, it was a lot of miles and a lot of days.

Neither gives a full answer. But then nothing gives a full answer. No matter
how closely you examine a subject there are still questions. The very
essence of chaos.

It is, of course, the factors that we don't know that make up the
difference.

The data in each is simply the data. More is almost always better. It's for
this reason that I wish more people would do as Caffyn did.

But, Matt's expertise notwithstanding, my gut feeling is that I can move my
kayak faster from point-to-point by using the rudder than I could without.
That's not to say that Matt could.


> I wonder what kind of statement Caffyn would make if he had paddled a
> Mariner XL around Australia. :-)
>

Perhaps we could talk him into it. :)

Craig Jungers
Royal City, WA
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