I have been working through the floor on my '72 boat. Looks just like Mark's on the restoration page. Contrary to what I've been told here, I purchased marine plywood (it's what everyone recommended up here and its what the previous owner used when he redid the floor 25 years ago). I have also been told that I MUST be using epoxy fiberglass resin because its stronger, water based, and safer. But, I am realizing that epoxy resin is extremely expensive. About $75 for 2 quarts. I've already burned through 4 quarts for the stringers. Should I continue with epoxy as I continue? Or can I switch to a gallon jug of polyester resin to finish the floor? Andy M
Andy I suggest you use vinylester resin. That is what I used. It is much better than polyester, but much cheaper than epoxy. As for the marine plywood - here is the concern..... What you want - your goal here - is to have the resin soak into and thereby bond with the plywood. The problem with treated plywoods like marine plywood is that the wood is already saturated. This tends to cause the resin to NOT SOAK IN and you then can end up with delamination of the fiberglass from the wood surface. It is for this reason that it is recommended that regular, high grade plywood be used. One of the marine fiberglassing books I read at the time I did my project actually suggested washing the plywood down with acetone before glassing and also mixing some acetone in with the resin before applying it to the wood before laying down the glass. The acetone causes the resin to become more voliltile and actually makes the resin soak deeper into the wood, creating a better bond. This is what I did. Now--- if you are using regular plywood, you should coat the bottom side (that will be on the stringers) with resin/acetone mix before putting it down. This will seal and protect the wood in case you get water under the floor - which you shouldn't if you do a good job on the floor. Marine plywood is great for wood that will be exposed to the elements. The idea here, however, is to use wood that will bond with the resin and NOT be exposed to the elements. Also - treated plywood is HEAVY. I have also heard the argument made that a rotting floor is not a bad thing because it lets you know that you have water under your floor - thereby letting you know that action must be taken. A solid, marine plywood floor with wet, heavy floatation underneath isn't doing you any good. I guess you could debate that point, however... If you are going to use treated plywood, it is best to leave it out in the sun for week or two of sunny days to make sure it is as dry as possible. Also - no matter what plywood is used, you want to rough up the surface with a grinding wheel before glassing over it. This will help the resin bond. Hope this helps. MarkBano
I agree with Mark regarding resins and wood, but be careful now that you've used epoxy on the stringers. Epoxy sticks very well to polyester or vinylester resin (or just about anything else), but not so well the other way around, ie if you're looking for a bond now between your floor to your stringers via resin, you may not get it by switching at this point.
