: Resin is considered 12 times as strong as the wood that surrounds it, at
: least that is what the literture of the Gougeon Bros. syas about West
: system resins. That is a pretty impressive increase in strength, as you
: have noted. Add glass and the strength increases even more. Much more!

: Consider the tip of almost any fiberglass fishing pole. Theyn are typic`ally
: under 1/8th inch in diameter and made from linear strands of fiberglass
: bound with a plstic resin. Those tips are strong enough to lift a 5 to 10
: pound fish (live wriggling weight) and they flex a lot rather than snap.
: Of course, put enough weight on them and they do break.

: Filling the gaps with caulking adds no strength. Filling the gaps with the
: equivalent of a fishing pole adds some strength from the fiberglass and
: resin.

: If the strips are 1/4 inch thick and the interior bevel is truly awful at
: most there would be a groove as deep as the strips are thick, or 1/4 inch.
: I'd guess the workmanship is a lot better than that, but at points it
: could go to anywhere from 1/8th to 3/16ths deep. Even with the shallower
: amount, packing the area with glass would give you a linear strip of
: fiberglass with a triangular cross section which would be stronger than
: the typical tip of a fishing pole. Do that for the grooves between 45
: strips and you have 44 thin fiberglass stringers which, if you removed the
: wood completely, would be almost strong enough to cover with a skin and
: use as a kayak frame.

: The thickness of the fiberglass covering on either side of the wood is about
: 1/32nd of an inch, or about 0.030 inches. The glass packed into a groove
: 1/8th inch deep would give a strengthening "rib" to that
: 'glass" skin which would be 4 times thicker than the skin alone. Such
: an addition would increase stiffness and strength. But it is a messy thing
: to do!

: Usign shorter chopped strands of glass fibers to reinforce plastic resin is
: commonly done. We make the filleting mix for S&G kayak construction like
: that. And it works well. Longer strands of glass fibers give greater
: strength in such mixtures than very short glass fibers. So, that's the
: origin of the idea of using very long glass fibers laid linearly in the
: grooves, rather than using a "dookie schmutz" mix of the shorter
: fibers

: Sorry if that wasn't clearly stated. It wasn't supposed to be an analogy but
: a contradiction. The usual caulking is indeed for watertightness, and not
: for strength. However, using the same manner of applying caulking, that
: is, packing something in the seams, you could increase the strength a
: small amount by using very strong materials, materials which had a much
: greater strength than the traditional caulking. In this case you can make
: the thickness of the fiberglass much greater along the lines of the hull
: without making the hull thicker. Instead you fill in the gaps with linear
: glass strands.

: Your woven glass cloth which sheathes the wood has more than enough strands
: of glass running across the direction of the strips to hold them together.
: Very short crosswise or randomly oriented glass fibers in the grooves
: would not be as useful, nor add s much strength for the weight they would
: add.

: Anyhow, it is a messy proposition, and nobody does it. Kind of unexplored
: territory.

: Thanks for your comments

: PGJ

Hi Paul,

The wood is a core, all it has to do is be firmly attached to the skins and keep those skins the same width apart for it to work. A filler that's complicated and heavy is just that, complicated and heavy, serves no purpose.

I use West resin's microlite filler if I have a problem with roughness inside, adds almost no weight, is very easy to sand smooth and the epoxy sticks to it wonderfully, and as a filler it streches the epoxy a really long ways. Getting a spreadable filler with this stuff require a bunch of filler, much more than you'd normally use, makes a little epoxy into a lot of filler.

Bill H.