[Paddlewise] Stiffness

I haven't had time to respond to the Construction thread of a while back
although I sure wanted to--several times.  Now is still not the time.

Energy from a paddle stroke that goes into flexing the kayak is lost for
propulsion. A racing kayak is as stiff as possible. A soft kayak is not a
lively kayak as some have called them. A soft kayak (inflatable, skin on
frame, or flexible plastic) is a dead feeling kayak as it absorbs energy
rather than responding in a quick and lively manner to its application.
The performance of a soft kayak therefore doesn't match that of a stiffer
version of the same kayak shape.
This doesn't mean there are no advantages to a lack of stiffness in other
areas. A kayak that flexes with the waves can be more sea kindly than the
same shape that is rigid. For example, Corry Freedman of Spirit Line Kayaks
(he makes the nicest Aleutian kayaks I have ever seen and paddled) made a
fiberglass mold from one of his favorites with the idea of marketing it in
fiberglass. I paddled both the fabric kayak and the glass version. While
there was a lot of similarities (and some performance advantages to the
stiffer kayak) there was one major disadvantage. The glass version had a
very wet ride. The same shaped skin boat flexed and allowed the bow to rise
with the waves so the water didn't easily wash over the front deck. The
glass baidarka project was scrubbed. This doesn't mean that all glass kayaks
will be wet but it does mean that they need to be different to be as dry
riding into steep seas as a flexible kayak.
Matt Broze
http://www.marinerkayaks.com

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