Subject: baidarka R: stability/performance vs. flexibility
From: Stefano Moretti (stmoretti@tin.it)
Date: Tue Dec 26 2000 - 13:31:11 EST
The french have a very basic approach to boatbuilding: "what is it meant
for, what the programme".
Boats are the evaluated against this designer statement. Does the boat fill
the purposes ? How much so ? Does it go beyond that goal, and how?
I find this attitude pretty sound and useful. more than comparisons that
are not related to any specific goal.
Stefano
----- Original Message -----
From: Bill Leonhardt <WJLeonhardt@bnl.gov>
To: <baidarka@lists.intelenet.net>
Sent: Thursday, December 21, 2000 7:54 PM
Subject: Re: baidarka stability/performance vs. flexibility
> 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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