Date: Mon, 10 May 1999 09:40:50 -0700 (PDT)
From: Ve Smith <ve_hengda_smith@yahoo.com>
Subject: Re: baidarka going - was slow
To: baidarka@lists.intelenet.net
--- John Winters <735769@ican.net> wrote:
>
> A small but important point is that paddles
> ventilate but do not cavitate.
> Caviation is the outgassing of vapour under very low
> pressures. Ventilation
> is the sucking of air down the back face of the
> paddle
An interesting point. My experience is related more to enclosed flow
(pumps and turbines), which do cavitate (and sometimes in not as
extreme conditions as you would expect) and make a sound similar to
what I experienced. Essentially, it feels and sounds as if I were
paddling through sand-unlikely in 20 ft of water, unless my powerful
stroke is stirring it up from the bottom. Since I use a paddle with a
narrow 32' long blade, and can produce the phenomenon with the balde
completely immersed vertically, I had discounted ventillation as the
cause, although I expect you are correct and that really is it.
If that's the case, it should stop if I put a cavitation plate (which
should be called a ventillation plate) on the blade below the point of
immersion, eh?
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