So you are thinnking of using polyester to cover the exterior a
plywood hull.

Polyester is fine under certain conditions. Unfortunately the
conditons aren't generally known. There has been so much
advertising and hype surrounding epoxy, compared to polyester,
that there is not enough interest in finding out what the
conditions for using polyester are.

If you use polyester without knowing the conditions under which it
works you are taking a chance.

I owned an old mahogony strip 20 ft sailboat which had been
covered with polyester by the builder. The only place it gave
problems was at the centerboard slot where it came away from the
hull. I assume it was because of the stress on the hull at the
slot.

One way of saving money is to only cover the hull below the waterline in
epoxy, and paint the hull above the waterline. TF Jones does that with
plywood boats.

Another technique Jones has used is to make the bottom of the hull of
polyester and fibreglsss and the topsides of plywood. Its not to save
money but to get a bottom hull shape that can't be done in plywood panels.
However you could make the bottom panels of a plywood design of polyester
and fibreglass and the topsides of plywood. The fibreglass panels are made
on any good flat surface and put on the boat as if they were plywood panels.

I've not used epoxy to cover a hull but I've read it takes 3 layers to
waterproof the hull. See, for example, David Gerr's "Elements of Boat
Strength". Our local public libary has a copy.


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