Re: [Paddlewise] Hull speed and Olympic Kayaks

Dirk wrote:

> Some time ago I asked the ICF about their rule that only convex lines
where allowed, which to my memory used to be no concave lines allowed? Since
I cannot understand  the only convex lines rule, because I see a lot of
straight lines or even concave lines on the racing boats, and maybe the only
sort of canoe that could somehow comply to these rule might be a Grumman for
instance?
> I never got any explanation from the ICF...

This rule caused enormous problems because it specified convex waterlines
and sections. You can see the loop hole in that.

How do you establish the waterline and section planes? The ICF failed to
think of that.

When I designed the Stealth canoe I took advantage of that and the boat had
definite concavity aft but as long as you measured the waterlines and
sections relative to "MY" base line everything had convexity. The boat
control people passed the boat but when one of the German measurers saw it
perform he tore off the passed sticker and declared it an illegal boat. It
took many months of appeal etc. but finally the boat was passed a week
before the Barcelona Olympic. Too late for the paddlers to train in the boat
(it had unique handling characteristics) Oddly enough some of the German and
French boats had similar shapes. :-)

Strict interpretation allows the horns since all waterlines are convex. If
the hull surface extended up to the horns it would be concave so everywhere
it might become concave they just cut away the hull. Clever fellows those
designers. :-)

John Winters



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