Re: [Paddlewise] Stability/Performance. . .

From: John Winters <735769_at_ican.net>
Date: Tue, 19 May 1998 07:52:40 -0400
George wrote;

(SNIP on stability)

>
>        Necky has an article in its sales brochure that explains all this.
>In sum: Initial stability keeps the boat parallel with the water. . .
>Secondary stability keeps the boat from tipping over (capsize) in heavy
seas
>. . . The boat becomes more stable as it is leaned on it's side.
>
>        These stability characteristics are essential to understanding
boat
>design. And the reason the "tippy" boat may be the best choice for the
nasty
>waters.
>
>        Somebody help me out here. . . John Winters understands this
stuff!


I think you guys are just trying to change the subject because you are sick
of me harping on the risk thing. :-) Fair enough, I get the message.

Stability is an extraordinarily complicated topic. There are books written
about it. It is, as Dan mentioned, possible to have a boat that is too
stable and one that is too tender.

I  like Nick's comment (I think it was Nick) that every use has an ideal
stability profile. Problems usually arise when we make absolute statements
like wide boats are better than narrow boats or whatever. There are plenty
of examples of people making hairy passages in Nordkapps to support the
positive comments about them as good sea boats. There are also plenty of
horror stories too.

Keep in mind that, by naval architecture standards, sea kayaks are not
seaworthy craft in that they are not self righting. This means that the sea
worthiness of the boat is inextricably linked to the sea worthiness of the
paddler.

Skilled paddlers have navigated open ocean in open canoes while less
skilled paddlers have drowned in kayaks bedecked with safety gear on inland
waters. One should not draw any conclusions from this other than the band
width involved.

The ideal kayak (from a stability standpoint) is the one with the greatest
area under the righting moment curve, the greatest range of stability, yet
still having a low metacentric height. Sounds impressive don't it. The fact
of the matter is that many kayaks are pretty good in this respect but no
matter how good they still need a paddler that matches the boat (or vice
versa).

The casual paddler who only paddles in protected waters is happier and
probably better off in a wide flattish boat. The experienced paddler who
takes on gnarly conditions will probably be happier in a much more tippy
boat. The long distance open water traveller will be best off in a boat
with lots of secondary stability, a slow roll, and plenty of displacement
(see ideal boat above). And so on.

 Cheers,
John Winters
Redwing Designs
Specialists in Human Powered Watercraft
http://home.ican.net/~735769/





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Received on Tue May 19 1998 - 06:18:15 PDT

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