new seating - help with materials

[Wallrat]

I'm currently starting a rebuild of my 1980 SeaRay interior. The lounge/jump seats are gone to be replaced with a more modern wrap-around seating design. Engine cover/rear jump seats are going to be a 3 piece sundeck covering the entire rear portion of the boat. Driver's seat is going to be a captain's chair (purchased complete). I wanted to build the framework out of some 2x3 hardwood and then cover that with 1/2" marine ply. The ply is expensive, but do-able since I don't need a ton of it. So far the best I've found for the hardwood is about $5/foot for 2x6 phillipine mahogany. Is this the best I'm gonna do? Would it be possible to coat a cheaper wood in epoxy? I've got tons of epoxy laying around and its not like the wood will be exposed to sunlight except occassionally. Everything will be covered in vinyl or foam+vinyl.

[marshmat]

If it's all covered (looks don't matter) then AC exterior ply, with fibreglass/epoxy, would work. Of course, any wood will rot. If you want this to last forever, then use a high-density polyboard in place of plywood- it's pricey but will last a lot longer. Make sure you use marine-type vinyl, the stuff sold for camping trailers and sofas has a felt-like backing that absorbs water and encourages mould.