Pete,
If you are re-decking your tri I'd use ply. 3 coats epoxy each side making sure you remove any amine blush between coats and a layer of glass on the outside to prevent the grain from opening up and letting water in. I expect the deck would then outlast the both of us.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!