Subject: baidarka stability/performance vs. flexibility
From: Peter A. Chopelas (pac@premier1.net)
Date: Thu Dec 21 2000 - 13:27:34 EST
Jim brought up an interesting question about the rigid fiberglass baidrada
vs. the skin on frame ones that Cory Freeman has.
There has been a lot of literature published and much discussion (and
speculation) on this and the Paddlewise lists about the affects of
flexibility. I have recently had some off list discussions with another
list member about flexibility and kayak performance and an idea occurred to
me for which I would like the list members comments and input.
I one of my engineering professors used to say that one experiment is worth
a thousand expert opinions and I thought it would be easy enough to do such
an experiment since kayaks are small and simple enough to build.
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.
You would have to get at least two builders that want to build identical
kayaks of course. But this would allow a side by side comparison in the
same conditions.
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.
You would also want to plan to have a number of different skill level
paddlers trying them out and make fairly detailed notes on their
impressions and conditions in which they used them. It also might be
interesting to try a number of different stiffness of hulls; one really
flexible, one medium, one stiff and one real rigid. I suspect there is
likely a point where a hull being too flexible would be detrimental as well
and this would help us locate where that point is.
It would be interesting to learn which is better and end the speculation.
If the experiment and results is well written Sea Kayaker magazine might
publish it. And if done properly would end this constant second guessing
and debates, it may even result in changes in factory kayak design.
I suspect that there are some conditions that the flexible hull will out
perform the rigid hull, and other conditions which are just the opposite,
just like stiff and soft snow skis. I also suspect that if there was some
way to maintain torsional stiffness and make it relative flexible
longitudinally it would perform better than one that is both torsionally
and longitudinally flexible. But I am just speculating.
What do you think, any volunteers want to give it a try? I live in the
Puget Sound area a little north of Everett (where Jim Mitchell lives), I
was planning on building several skin on frame kayaks over the next year
anyway, one for me and one for my wife. The more data points we collect
the more meaningful the experiment will be. It might be fun to combine the
get together with one of the kayak gatherings we have in the area. I think
Cory is planning another skin boat gathering in Anacortes this coming March
or April, it would be a good place to run the experiment.
Anyone interested?
Peter
Arlington, Washington
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