Re: Jon boat: Adding plywood decking. How to seal
+1. You can even get spar varnish at lowes/HD, but you usually have to order epoxy. I'd say a few coats of Spar varnish followed by a top coat paint of your choice. Although, lots of folks just leave the wood unpainted after using the varnish. However, if you do paint Rustoleum oil based enamel is an oldie but goodie and holds up well on the water and you can get it just about anywhere. It takes a while to fully cure and can be a bit slick when dry, but it works great. I did several coats on 2 decks and 2 benches with less than a qt. Pay special attention to the cut edges and pick up some 3M 5200 (also at lowes/HD) to dip all of the hardware you may be using in prior to installation. (btw only use Stainless steel or aluminum pop rivets in a boat.)