> 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. 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. For this reason I
> would use 1/8 inch strips, this would give me two obvious benefits: 1-it
> would eliminate 50% of my wood weight, (about 10# as George already
> confirmed) 2- it would give me a higher percentage of resin saturation and
> wouldn't eliminate strength but would actually eliminate a weakness
> (unsaturated cedar). 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.

> If carpenters glue is used to hold our strips together we end up with a
> sandwich effect with our lamination. We have a epoxy layer adhered to a
> cedar strip center adhered to another epoxy layer. The cedar epoxy
> adhesion is quite good but cedar strips are weak and can split, causing
> seperation. The epoxy/ carpenter glue joint is very poor. For these
> reasons I would use epoxy to glue my strips, this would give higher resin
> saturation on the cedar (4 sides instead of 2) and would also bind with
> the inner and outer epoxy layups and form part of the laminate. The result
> of this is a laminate that is locked together nearly equally in three
> dimensions, giving a honeycomb type structure instead of a sandwich.(This
> would be even stronger because the two epoxy layers are only seperated by
> 1/8 inch strips.)

> The last thing that I would do is a double or triple layup of a very light
> fiberglass cloth. As I stated in previous posts, I think that this would
> be much lighter and stronger than a single heavier cloth layup.

From this line of thinking, if you removed all of the wood and added more fiberglass, the boat would be really strong and light, but wouldn't you then have a fiberglass boat? They're a lot heavier than the wood ones.

I work at a large airplane company. Composites is not my main job, but I have taken some classes on them. First of all the wood is there to separate the layers of fiberglass (it's honeycomb in airplane parts, which is not very strong in any direction except compression). This creates a larger moment of Inertia. Check out the stiffness chart on page 39 of "The Strip Built Sea Kayak", 1/4" of wood with 4 oz cloth is stiffer than 3/16" wood with 6 oz cloth.

If the thickness of the wood is decreased to save weight, then the composite system needs to be stronger to take the same load. Where I work, the room temperature epoxy's are supposed to be used for non-structural applications only and almost everything is done with a vacuum bag high temperature cure. One problem with this high temperature and wood is that any moisture would boil out of the wood at above 212 degrees causing delaminations (besides the damage it might do to the wood). There is a 200 degree cure that has almost the same shear modulus as the high temp cure.

There is also E-glass cloth and S-glass cloth. The S-glass is better, but more expensive.

I don't know 1/10th of the technology that goes into composites, but I do know that there are better systems out there than room temperature epoxy.

The point of all of this techno-babble is that yes George could possibly have a stronger-lighter boat, but which home-builder has or is willing to buy, the heat blankets, vacuum pumps, and all of the other stuff that goes along with non-room temperature cures? Especially when the existing boats are light enough and strong enough.

The Expedition Single has a sinkage of 98 lbs/in, so if it were 10 lbs heavier it would sink approx .10" further into the water. I have much bigger things than this to worry about.