"AB" ) writes:
Think of it this way:-
Polyester is a bonding resin, which means that it binds a material, I.E.
fibreglass by surrounding the fibres on both sides and through the fine
glass filaments. If you use it on ply then it cannot soak into the surface
and through to the other side to bind the plywood fibres.
Polyester does "soak into" the plywood, especially if given time by
lightening up on the catalyst and temperature. I've spread uncatalized
polyester resin on plywood and let it "soak in" before applying a second
layer with catalyst. I didn't put any fibreglass on the hull, just painted
over the cured polyester. Not scientific though. The small boat is only in
its second season so I'm not sure how successful it was yet. I've also
drilled lots of holes in wood to help polyester get a bite. I remember my
father doing the same thing when patching rust spots in an old car. I've
also done the same on the 14 year old car I have now.
I found the following reference in a book I read this afternoon
"How to Fibreglass Boats" by Ken Hanikson, published by Glen-L Marine in
1974 (Glen L Witt's company. Perahps email to Glen-L or Devlin would get
information they might have on the conditions under which polyester can be
succesfully used to cover a plywood boat.)
I found the above reference in "How to Beat the High Cost of Sailing" by
Richard Lyttle (1976). I also like "Frugal Yachting" by Larry Brown (1994)
although its not as informative. Brown sails a Potter 15 with his wife,
and the book is mostly about pocket cruisers that can be towed around on a
trailer. Since the original poster in this thread has already started to
build his boat these books are of limited interest, but I like them anyway
because they address the subject of sailing at least cost. Both books are
available from the Ottawa public library.
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