Treat or not treat marine grade ply

[produceguy]

I went to a boat shop a few days ago and they was redoing the interior on a pontoon boat and under the boat was bare wood.
I asked the guy that was their if it needed resin or something to seal it and he told me no because it was mgp.

Just curious.

 

[ezmobee]

Re: Treat or not treat marine grade ply

Marine grade plywood, contrary to popular belief, is not treated against rot. It's just a better quality ply that may feature better quality glue, fewer voids, and/or more plys. So draw your own conclusions from that

 

[gozierdt]

Re: Treat or not treat marine grade ply

+1 on above reply. The exposed wood will soak up water, and eventually the glues will
fail, or it'll rot, especially waywhere it's close to another surface like support beams. It
should be sealed.

 

[Midnight Krawler]

Re: Treat or not treat marine grade ply

Manufactures don't treat or seal the wood either. Just let it rot so you'll buy a new boat sooner.

 

[Island Seeker]

Re: Treat or not treat marine grade ply

I'm going through this right now. My project boat needs new seat backs. The wood just crumbles. Will use 3/4" ply with no voids & seal with resin.

 

[jayhanig]

Re: Treat or not treat marine grade ply

I just replaced the hinged seat backs that form part of my engine cover. The original plywood was completely rotted at the edges. I purchased marine grade plywood and used pressure treated lumber for the supports. The marine grade plywood was completely sealed on all sides with West System 105 epoxy mixed with 206 hardener. Then it was SS screws to put it together and SS staples to attach the new vinyl covering for the seat backs (with foam scavenged from the original seats underneath the vinyl). It turned out well and I expect it to last much longer than what was there before.

All MGP gives you is a better grade of plywood without voids underneath and better glue, as others have mentioned. But you still have to protect it if you want it to last.

 

[fishrdan]

Re: Treat or not treat marine grade ply

There are many types of marine grade plywood and the correct type of "marine" plywood for pontoon's is called pontoon decking, it's a CCA treated plywood that is rot resistant. It might have looked untreated since it wasn't green, but that's because of the CCA treating, it gives the wood a yellow/orange color. Now, I would have been far more concerned to have seen green treated plywood in the toon as the green treated wood will eat aluminum. I'm not saying they didn't use untreated marine plywood, if they did, they used the wrong type of plywood.

 

[DuckHunterJon]

Re: Treat or not treat marine grade ply

Not unheard of. A friend just bought a toon (don't remember the manufacturer), and one of the first things I noticed looking at the underside was that it was standard grade, non treated, non marine plywood for the deck. I was very surprised.