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Kayak and Canoe Design Bulletin Board
Re: Wide sterns *Pic*
Posted By: Nick Schade - Guillemot Kayaks In Response To: Wide sterns (sam McFadden)
Date: Monday, 17 June 2002, at 10:20 a.m.
I had been thinking about this kind of shape for a while. I ended up building the Aleutesque because what I had drawn up looked so cool I figured it would be worth it even if the performance was not great.
But I did have a theory going into it. A "transom" stern may have the effect of making the boat appear longer in the water than it actually is. At speed the water just sheets of the end (like it is planing) and leaves a depression in the water that acts like part of the hull as far as the wave making is concerned. I don't know if this really works, but it is the theory.
This also lets me keep the width of the boat farther aft which like Hans suggested improves the stability in an otherwise narrow boat.
I do think that on a big wave the full stern section should help support the boat to the point that it may actually plane. However, it is possible that there is so much lift in the stern that it keeps the boat quite flat, which may force the bow down into the water ahead of the wave. This would be particularly true on short wavelength surf. The result may be that the boat has a tendancy to perl or broach.
I need to try the boat in something other than flat water to get a better feel for the answers to some of these questions.
: I was enjoying the images from meet at the beach (see the building site) and
: was excited to see Nick’s Aleutesque. I’m interested to read any comments,
: in particular from Nick, about the volume distribution and aft shapes of
: the design. Like several others, I have often wondered if sea kayaks could
: benefit from full aft sections - similar to light displacement sailboats.
: This last year I began toying with design and played for some time with a
: hull shape thagStrd a wide stern, but for now I have left it alone in
: favor of a more normal looking “pointed” boat.: My concepts of hull shape come from “what looks good” rather than an
: understanding (none) of fluid dynamics. I have relied a bit on Kaper to
: keep me from straying too far from the norm, but have not yet obtained the
: necessary references to understand the empirical foundations for it - so
: its been a ‘black box’ tool for me.: I assume that pointed sterns are the norm because, except when surfing, we
: are operating in displacement mode. Also, playing with the wide stern
: shape raised a few questions about how to maintain tracking, without going
: to a shape like the SOF Aleut boats – which strike me as a bit tortured -
: or relying heavily on a skeg or rudder.
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