Subject: Re: baidarka stability/performance vs. flexibility
From: Bill Leonhardt (WJLeonhardt@bnl.gov)
Date: Thu Dec 21 2000 - 13:54:12 EST
At 10:27 AM 12/21/00 -0800, Peter Chopelas wrote:
---SNIP
>My idea is this: get a couple of builders together to build identical
>baidarkas except for the frame stiffness, then get together with a group
>of paddlers with different experience levels and actually compare the
>performance under different paddling conditions.
>One hull would be fairly rigid and tight lashed, another flexible and loose
>lashed. All other dimensions, materials etc. would be as close to
>identical as possible.
>
---SNIP
Peter,
To apply the results of the tests you propose, it might be useful to
conceive of a way to measure and quantify looseness (tightness) so two
people building the same design in different places can achieve the same
level of stiffness. There should also be more then two values of
looseness, however that might make the experiment more difficult.
---SNIP
>Another alternative would be to build a single loose lashed kayak and wrap
>it with plastic and duct tape and give it a tryout, then re-lash it and
>perhaps add some stiffeners to the frame, and again skin it with plastic
>sheet and duct tape and try it again. Of course you would lose the
>advantage of being able to try it out side by side but you would only have
>to build one experimental hull.
>
---SNIP
An alternative here might be to take the loosely lashed boat and tow it
with a scale (to measure towing force) and compare this to speed (GPS?).
This could be done on the same boat with different levels of tightness. By
conducting tests on several levels of tightness, you can determine if any
effects you measure are linear or not and, perhaps, be able to recommend an
optimum level of looseness for that design. Of course, this is optimizing
for speed and not stability.
Just my 2 cents...
Bill Leonhardt
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