[Rick TYler]

Originally Posted by spc295

epoxy will help a lot, it also gets red of flex in wood poles.

I hate to disagree, but I find this to not be true in the boat-building I've done. If you coat the wood with epoxy and a layer of fiberglass, it will be a little stiffer, but not much. The only way to really stiffen a component is to externally brace it, make it from something more naturally stiff (and not many materials are stiffer than wood for a given weight) or increase the cross-sectional area. Using epoxy and glass to stiffen a plywood panel only works if the glass is pretty beefy -- like 12 ounce biaxial at least, or multiple layers of woven glass. Of course, this increases the cross-sectional area of the panel, which likely is what adds to the stiffness. If I wanted to stiffen a 6mm plywood panel I would either glue battens across it, or laminate another layer of plywood to it.