: Curious. In Jonathan Hanson's book "Complete Sea Kayak Touring",
: the author writes "Although they are perfectly efficient, plywood or
: fabric-covered, wood-framed kayaks would be prone to damage on an
: expedition, with a hundred or more pounds of gear inside (page 6; the
: context is on amazon.com preview if you want more).

: Sounds counter to what I would expect, but I have not seen any facts on this.
: Can you help?

Ok, this does indeed change the situation.

When a fabric skinned kayak is loaded with a lot of gear (probably in gear bags or dry bags) that gear is going to eventually press against the skin someplace.

That would make it more difficult for the skin to deflect when it encountered rocks or other underwater materials. And if it doesn't deflect, then it stands a better chance of being damaged. Of course, that depends a lot on the materials the skin is made of. Some of the modern synthetic-rubber-coated and synthetic-fiber-reinforced skins are as durable as automobile tires.

Now, you don;t gert that effect with a plywood kayak, but as Hanson mentions those kayaks which are woodframed and plywood covered, I assume he is thinking of a much older style of kayak construction which predated fiberglass completely. In the construction descriptions I have for a typical one of these older boats the plywood panels are screwed to the wood chines, and the length of the seam is "sealed" with a "gasket" which is merely a strip of cotton fabric soaked in an oil paint. (these plans pre-date latex paints, too!) Such seam sealing was deemed adequate for the time, and people expected the swelling of the wood to keep the seams tight. A seat raised above the bilge, and bailing were common, too. The flexing of a wooden boat in hevay waves oer time could loosen some of those seams and permit leakage. For a boat used for day trips this would not be a handicap as the boat could be drained frequently, and a fresh coat of paint over some caulking, would frequently soak in and seal the tiny leaks, rejuenating the boat. But on a long expedition the repairs might be more difficult.

Of course now we make most plywood boats with a stitch and glue technique. In this type of construction the panels are not joined by screwing them to a chine. Instead the panels are temporarily joined to each other at the proper angles, and then a thick epoxy mixture fills each long seam. That thickened epoxy fillet, combined with the fiberglass tape which goes over it, becomes in effect the chine. But this time, that chine is molded into a perfect fit, and glued along a wide area (the width of the glass tape) with a glue (the epoxy) which is waterproof. Nothing comes loose, and the seams won't leak. Covering the hull with an entire layer of glass cloth and resin provides another continuous layer over the wood which keeps out water, too.

this is one advantage that wood-cored boats have oer solid fiberglass boats. Should a solid fiberglass boat receive a strong enough impact to crack, that cracking goes all the way through the hull. On a wood-cored boat there are two separate layers of fiberglass which are separated by a layer of wood strip or plywood. Should something penetrate the outer layer of fiberglass, the inner layer *may* stay intact. Hit it hard enough and you can penetrate both layers. In this case the wood fibers *may* swell when they get wet, and seal the leak, or reduce the amount of water coming in. There are no guarantees, but you get more chances with the wood-cored hulls.

The quote from Hanson's book doesn't even mention strip built kayaks, so I assume your question was an extension of Hanson's thought. Hope I was able to fill in some thoughts on that.

PGJ