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Re: George Roberts' Challenge
By:J . P. Scheib
Date: 8/27/1999, 5:24 am
In Response To: George Roberts' Challenge (Ian Johnston)

> From my figuring (thinking mostly) I feel that the weakness in a cedar
> strip kayak is the cedar strips. The strength in a laminate is in the fact
> that all the structural components (cloth and strips) are locked together
> by the binding component ( epoxy resin), so that nothing can move without
> moving everything else. A third and maybe not so obvious benefit of 1/8 inch
> strips is that the distance between the inside and outside epoxy layups
> would be reduced and in a laminate this is important to keep everything
> tightly interlocked and this will become important when glueing the strips
> together.

This reasoning does not seem right to me. A strip canoe or kayak is considered a composite construction so the cedar only serves as a spacer between the fiberglass layers. This is similiar to using foam or endgrain balsa as the core as they do in larger sail or power boats. The thicker the sandwich material the stiffer the panel because the composite can be thought of as an I beam. An I beams stiffness is determined by the height of the I. Therefore a 1/4 inch thick hull will be stiffer than an 1/8 inch hull.

The trouble with the strips is that they are not
> saturated with resin so their fibers are not locked in with the rest of
> the laminate except for some penetration on the surface.

But they are locked together by natures version of expoxy and this is strong enough because it only has to resist an internal shear force not the bending force applied external to the panel which is caried by the 2 layers of fierglass.

Messages In This Thread

George Roberts' Challenge
Ian Johnston -- 8/27/1999, 4:15 am
Re: George Roberts' Challenge
Rick S. -- 9/3/1999, 12:42 am
Re: "ultimate layups"
lee -- 8/31/1999, 11:11 am
Re: "ultimate layups"
Mike Hanks -- 9/1/1999, 4:17 pm
Re: "ultimate layups"
lee -- 9/14/1999, 10:18 am
Re: "ultimate layups"
Paul G. Jacobson -- 9/15/1999, 1:44 am
Re: "ultimate layups"
Mike Hanks -- 9/14/1999, 9:05 pm
Re: "ultimate layups"
lee -- 9/16/1999, 2:46 am
Re: "ultimate layups"
Mike Hanks -- 9/16/1999, 10:51 am
The Challenge: Don't forget this!
Jan Gunnar Moe -- 8/30/1999, 3:57 am
Re: George Roberts' Challenge
Jamin -- 8/29/1999, 9:05 pm
Re: George Roberts' Challenge
Dale Frolander -- 8/28/1999, 2:26 am
Re: George Roberts' Challenge
Ian Johnston -- 8/28/1999, 9:34 pm
Re: George Roberts' Challenge
Dale Frolander -- 8/28/1999, 10:27 pm
Re: George Roberts' Challenge
Jeff DeJongh -- 8/29/1999, 3:18 pm
Re: George Roberts' Challenge
Ian Johnston -- 8/29/1999, 5:46 pm
Re: George Roberts' Challenge
Dan Lindberg -- 8/29/1999, 8:43 pm
Re: George Roberts' Challenge
Jeff DeJongh -- 8/29/1999, 7:36 pm
Re: George Roberts' Challenge
Ian Johnston -- 8/28/1999, 11:06 pm
Re: George Roberts' Challenge
Don Lueder -- 8/27/1999, 8:03 pm
Re: George Roberts' Challenge
jay roberts -- 8/27/1999, 5:10 pm
Re: George Roberts' Challenge
Edgar Kleindinst -- 8/27/1999, 10:49 am
Re: George Roberts' Challenge
J . P. Scheib -- 8/27/1999, 5:24 am