Subject: Re: baidarka stability/performance vs. flexibility
From: James Mitchell (mariner@seanet.com)
Date: Fri Dec 22 2000 - 02:01:12 EST
Lew, did you ever build that boned hull we were discussing? Harvey, have
you ever built a boned frame?
----- Original Message -----
From: "Tom Wainright" <wainair@yahoo.com>
To: <baidarka@lists.intelenet.net>
Sent: Thursday, December 21, 2000 9:12 PM
Subject: Re: baidarka stability/performance vs. flexibility
> Good points, I think you would find the amount of flex
> would be according to the preference and skill of the
> individual paddler. I understand in the old boats of
> the aluet they used Ivory sliders in the joints so
> they would slide more freely, and that they would add
> ballast to the bow and stern to magnify the undulation
> of the boat in the waves to increase speed and reduce
> paddling effort.I can't remember were I read these
> things but I'm sure Wolfgang or Mr. Zimmerly would
> have an idea. Tom
> --- "Peter A. Chopelas" <pac@premier1.net> wrote:
> > 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
> >
> > -
> > Baidarka Mailing List - All postings copyright the
> > author and not to be
> > reproduced outside Baidarka or Baidarka archives
> > without author's permission
> > Submissions: baidarka@lists.intelenet.net
> > Subscriptions:
> > baidarka-request@lists.intelenet.net
> > Searchable archive:
> > http://rtpnet.org/robroy/baidarka
> >
>
>
> Yahoo! Shopping - Thousands of Stores. Millions of Products.
> http://shopping.yahoo.com/
> -
> Baidarka Mailing List - All postings copyright the author and not to be
> reproduced outside Baidarka or Baidarka archives without author's
permission
> Submissions: baidarka@lists.intelenet.net
> Subscriptions: baidarka-request@lists.intelenet.net
> Searchable archive: http://rtpnet.org/robroy/baidarka
>
>
-
Baidarka Mailing List - All postings copyright the author and not to be
reproduced outside Baidarka or Baidarka archives without author's permission
Submissions: baidarka@lists.intelenet.net
Subscriptions: baidarka-request@lists.intelenet.net
Searchable archive: http://rtpnet.org/robroy/baidarka
This archive was generated by hypermail 2b27 : Mon Jan 01 2001 - 01:00:03 EST