Is there any reason not to use pressure treated wood when rebuilding seat bottoms in a fiberglass boat?

I have done it several times. It is a little heavier, and if you have to glass it, it sometimes does not bond as well. Treated wood has CCA (Chromated copper arsenate ) in it, so don't eat it LOL

Why not use composite wood? http://coosacomposites.com/

Also look into MDO engineered plywood....I found some at my local Menards....its rated for outdoor use...i've used it before for small seat repairs and has held up great and just as easy to work with as normal wood..

I've grown sick of wood in boats because it always fails sooner or later, are their other options and why are they not more prevelent (I probably answered my own question)?

MDO is what they use for highway sign boards. I've put a chunk of it in a bucket of water for a month and it never swelled. It has a paper skin that can be painted.

I would think Coosa would be much lighter & stronger. Will be pricier tho.

You can buy sheet pvc from Home Depot, it is 1/2" but it is no where near as rigid as wood. I used starboard to rebuild my seat base in my boat.

If you bond sheets of PVC, does it get stronger like plywood?...I guess at a certain point it becomes an impracticle thickness...there must be something else strong and light. Even better might be a composite in a liquid form that can be shot into a mold...what might such a composit be?

Maybe TAP plastics has a viable material.

http://www.tapplastics.com/product/p...c_sheets_rolls