Marine Plywood

[shakerboater]

I'm re-decking a Harris Flote Bote and need 4x8 sheets of plywood. Has anyone seen Marine Plywood around the Cleveland - Ashtabula (Ohio) area. I'd like to pickup locally rather than have it shipped from Overton's, etc. Boat supply stores nearby do not carry it, they only have the plastic decking. Thanks.

 

[gcboat]

Re: Marine Plywood

I'm just thinking out loud here but you might be better off buying some A/B or A/C exterior ply from Home Cheapo or Lowe's or wherever and applying a coat or two of either poly or epoxy resin. The epoxy will cost you more but it is a superior product compared to the poly. Or you could go this route:
http://www.rotdoctor.com/products/product.html

 

[shakerboater]

Re: Marine Plywood

Thanks, gcboat. After I posted this, I read more posts here on "Marine Grade" vs. ply from Lowe's, etc. Sounds like a plan to use the exterior ply and coat with epoxy.

 

[Chris1956]

Re: Marine Plywood

Shaker, I use pressure treated 1/2 CDX Plywood for the floors of my boats. I rack it in the garage or leave it in the sun to get very dry, fit it, coat the bottom and edges with poly resin and then install it and coat the top with two layers of light duty glass and 3 coats of polyester resin. It works very well.

 

[BillP]

Re: Marine Plywood

Use pressure treated ply on your pontoon boat. Most of the pontoon mfgs use it for their decks...the ones who don't have rot sooner or later. Coating non treated ply is a distant 2nd best. I have a 1996 toon that came with pt decks and the ply is still like new...it's unpainted on the bottom with carpet on top.

B.

 

[rheagler]

Re: Marine Plywood

Be careful using any pressure treated lumber around aluminum. The chemicals especially in the ACQ treated stuff will eat through the aluminum. Just my .02.

 

[Robj]

Re: Marine Plywood

Use CCA treated if you can find the stuff. Otherwise use ACQ, and regardless of what type of treatment, use SS screws. ACQ will eat Aluminum. Make sure it is very dry, it took about 1 month indoors for mine to dry.

Have a great day.

Rob.

 

[BillP]

Re: Marine Plywood

Yep, use 3/4" thick CCA from Lowes. Hand pick the best sheets and let them air dry for a month or so. A fan blowing on them 24x7 does it way faster than without a fan. My toon has a rubber gasket between the alum frame and pt ply but poly or silicone caulking would work as an isolator too. The only corrosion my 20'r sees is where SS ubolts are attached directly to the alum frame at the corners (for my boatlift cables to hook on). I redid them a few yrs ago with nylon bushings and washers to isolate them. It basically stopped the corrosion process.

 

[Joe_the_boatman]

Re: Marine Plywood

You can get CCA from Lowe's? Supposedly the only way anyone can manufacture (and sell) this stuff (after 2003) is for specialty applications (marine uses being one of them).

That's why marine plywood is CCA, and why it's $80 a sheet

The new pressure treated wood contains copper instead of arsenic. Hence, galvanic corrosion when in contact with aluminum.


PS - if it is available from Lowe's, I'm all over it. I'll ask next time I'm there.

 

[BillP]

Re: Marine Plywood

You can get CCA from Lowe's? Supposedly the only way anyone can manufacture (and sell) this stuff (after 2003) is for specialty applications (marine uses being one of them).

That's why marine plywood is CCA, and why it's $80 a sheet

The new pressure treated wood contains copper instead of arsenic. Hence, galvanic corrosion when in contact with aluminum.


PS - if it is available from Lowe's, I'm all over it. I'll ask next time I'm there.

I'm in Florida and CCA ply is allowed and still used for commercial and dock use but not residential. Lowes and HomeDepot have never stopped selling it across the counter here. PT marine ply has always been CCA. Before CCA it was a petroleum process that wouldn't let paint, glue or resin stick to it.

 

[escapade]

Re: Marine Plywood

so what exactly does CCA stand for? or is it just a dif name for exterior ply?

 

[Joe_the_boatman]

Re: Marine Plywood

Chromated copper arsenate.

 

[seven up]

Re: Marine Plywood

Shakerboater,

Copper, Aluminum and Stainless Steel ? Whew !

You should junk the boat now and save yourself alot of time, money and other problems.

 

[BillP]

Re: Marine Plywood

The pt ply deck on my 20' alum toon is 11yrs old with carpet on top and nothing on the underside where water hits it. It still looks perfect and has no delamination, rot or soft spots.

When I redid the stainless eyes on it used for a boatlift I installed nylon washers under the ss washers to help insolate the two metals. That seemed to greatly slow down electrolysis but a better way is to also use nylon bushings to isolate the bolts. This would work fine on the new deck. The mfg on my boat used black rubber washers to isolate the deck fasteners and the same rubber stuff in strips under the wood where it sits on the alum cross members.

 

[shakerboater]

Re: Marine Plywood

Thanks for all the helpful info. While at Home Depot, I found 3/4" underlayment, Birch, that was hard to pass up. The exterior ply at the local yards and Lowes and Home Depot were shoddy and I was staying away from pressure treated due to a potential reaction with the aluminum. After all this, I took off the old deck (original panels from 1975) and it appears that the ribs are actually galvanized steel. Where there was the most rot in the wood, there was a good deal of surface rust on the ribs/crossmembers. They're still solid, only one has enough rust to flake, but each shows some rust. I don't know the term, but the welded "stands" from the pontoons to the crossmembers are aluminum as expected with no signs of corrosion or any reaction where they meet the crossmembers. Anyway, I went with these birch sheets and a good poly to seal. Hopefully, I won't be kicking myself later. I'll still use a good caulk, stainless fasteners, and rubber washers/grommets as much as possible.