Date: Fri, 10 Oct 1997 16:53:16 +0200 (MET DST)
From: Gerald Maroske <kayak@elwood.gpi.uni-kiel.de>
To: baidarka@lists.intelenet.net
Subject: Re: KAYAK DESI
In-Reply-To: <199710101341.JAA25424@www.onlink.net>
On Fri, 10 Oct 1997, John Winters wrote:
> Paul wrote;
> (SNIP)
>
> > >With all due respect to George, I don't know that this is valid. Rarely
> > >would the relative velocity past the stern be so great as the velocity
> at
> > >the bow (unless one were paddling backwards).
> >
> > ??? In following seas or in surf the the swells will over take the boat,
> > therefore the velocity ? from the waves coming from the stern will push
> > the boat. Or am I missing your point? The transome shape of the Aluet
> > kayaks stern would (it seams to me) take advantage of this push.
>
> If the object is to push the boat then one has to wonder why a streamlined
> shape that is designed to reduce resistance (from astern) is desired. The
> fullness above the waterline does add buoyancy and that will help but it is
> not necessarily shown that that method is any better than simply filling
> out the stern sections, or adding overhang, or using a more hard chined
> shape aft.
>
> Yes, the following seas might be traveling faster than the boat but it is
> the relative speed that matters and that is quite low (except in breaking
> seas where the water particle velocity can be in excess of twice the wave
> celerity). In any case, it can be shown that a wider, flatter stern will
> offer greater resistance (such as some of the Greenland and Labrador boats
> because of their greater exposed area.
>
> My point is that the baidarka stern may not be an efficient way to achieve
> this particular end. Whether it is a good compromise between one objective
> and another is also not clear. I only wish I had the time to study this in
> more detail.
>
>
> Cheers
> John Winters
> Redwing Designs
> Specialists in Human Powered Watercraft
> http://www.onlink.net/~jwinters
>
I think the main difference is the same as in building oldfashioned
and modern racing yachts:
The old ones had much overhang while modern boats have a cutoff stern.
But don't ask me why!
This opinion was published by George Dyson "Form and Function of the
baidarka" in Contribution to kayak studies.
Gerald