Greetings. I need a recommendation on the best method / product to seal marine plywood. I am having to replace the bottom of a 16 foot flat bottom river boat. The boat is about 20 years old and has been compromized and starting soaking up water. The original plywood was treated with "Cop-o-tox" Then assembled. After that several coats of Spar varnish were applied.
I would think advances have been made over the 20 years in products to use. I would hope to get a general consensus on the right product (s) to use to get another twenty years out of the replaced bottom plywood. Any help would be greatly appreciated.