replacing decks w/douglas fir and glassing over?

[phishown]

I need a few opinions regarding the use of treated douglas fir 3/4" plywood and glassing over with biaxial 24oz using polyester resin. I know I should let it dry out for some time....or the resin/glass want adhere properly. Is the entire concept worth while? I have a lead on some inexpensive fir ply.... If it is worth while my thoughts are to glass the bottom side with one layer and glass the top side with two layers....I have had one opinion that recommends glassing only the topside while letting the underside breathe and applying copper tox. I am considerig honeycomb composite / foam injected, also but its about 40% more expensive....Your ideas and opinions are appreciated! My hull is juniper planked by the way and I would never consider glassing it!
Mark

[Al Thomason]

Would suggest not to use Poly resin if you do this, use Epoxy. I am now replacing the fly-bridge sides on my Monk trawler. About 50% of the poly resin FGlass just pops off. The adhesion was not good with the Poly.

[Cuyahoga Chuck]

Epoxy/'glass laminates over plywood are a component on many modest sized (less than 35') stitch and glue hulls,today. But the designers usually insist that the inside and all the edges be sealed with epoxy too. The idea is to seal the wood from all moisture whether airborn or waterborn.
Glassing the outside of ply makes for a stiffer panel so it is possible, in some cases, to decrease the thickness of the plywood slightly.
Polyester would be a dead letter in boatbuilding except for the fact that it is an acceptible and inexpensive resin for all-glass hulls.
Charlie