: A neighbour is restoring his father's old cedarstrip/canvas canoe. He has
: removed the damaged canvas leaving flat ribs covered by thin (1/8" or
: less) 2.5" wide cedar strips. The strips are not tight to each other,
: but have approximately 1/16" gaps between them. Several of these
: strips are missing and will need to be replaced.

: He wants to eliminate the canvas and leave the outside as natural looking
: wood with the brass nail heads (attaching the cedar to the ribs) showing.
: His idea is to replace the missing cedar strips, leave the gaps and just
: fill them with epoxy/sawdust mixture, then glass the outside with one or
: two layers of 6 oz. fibreglass. There is not much strength with the very
: thin cedar, but he is hoping that by glassing the outside and using the
: ribs for strength, he can get away with just varnishing the inside, where
: the ribs prevent him from glassing. Any advice before he gets much
: further?

The gaps between those cedar boards are there for a definite reason. Those boards will expand slightly as they absorb moisture. YOu might want to check and see how those boards were attached to the ribs, too. Sometimes they are nailed near the center, but not near the edges. This would be done to keep the board in place, but to allow the wood to expand.

Now covering this with epoxy will keep the moisture out of the wood, so if you can completely cover BOTH sides of the wood with epoxy then you mgiht be able to do what you propose. However, if you glass the outside and varnish the inside then the wood will absorb moisture -- the varnish does NOT block water vapor completely -- and that will cause all kinds of problems. The wood will try to expand, and as it pushes against the resistance of anything which is placed between the boards it can only expand by "popping" or warping away from the ribs. This tends to loosen the brads holding the wood to the ribs.

the process is repeated in cycles as: the boat is used, absorbs moisture, and the wood expands. Then the boat is removed from the water, stored, it dries, and the wood shrinks back again.

Since there is no way to drive those brads back to retighten them, after a few cycles a rigid boat can turn into a very flimsy one.

While the appearance of the wood is desirable in a stripper, the gaps between the cedar strips on a canoe designed to be covered with canvas may appear irregular and objectionable.

If your friend is looking for a stronger, more "high tech" covering for the canoe, why not use a polyester material -- such as that used on skin-on-frame kayaks instead of a cotton one? Installation should be easier than with cotton canvas, as the polyester can be shrunk tight against the hull by applying a bit of heat. A clothes iron or a heat gun will do.

Paint is a wonderful finish for the outside of these old boats, with varnish for the inside. If you don;t use epoxy you will spare yourself the need to recoat the boat every year or two with varnish, to protect the epoxy from UV degradation.

Try to steer your friend into using more appropriate refinishing materials, similar to those used when the boat was first constucted. He'll be happier in the long run.

PGJ

: John