Marine Grade Plywood?

Hey all,
I’m in the middle of re-carpeting my boat and decided now that I have the carpet off, I should replace the flooring too. I’ve read about the debate over typical treated plywood vs. marine grade plywood. Marine grade is dried more than typical treated apparently? Alsoread that typical treated can eat away the rubber backing on the carpet? I was wondering if anyone has went through this and which way they went. Marine grade is expensive but if that’s what it takes, then thats fine. Does anyone know where marine grade can be purchased? Thanks for your help!

Menards has it I believe and the only way to go.

I’ve had marine grade in my boat for 32 years now. Its lasted two carpet jobs, the last one done in 2011. The wood is still in great condition. I varnished it heavy to start with.

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Menards has it I believe and the only way to go.

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Just looked at it Saturday.$50 for 1/2”,about $75 for 3/4.My store it’s special order,takes about a week.Think they use to stock it but not now.

Marine grade is not only drier it has no voids. Voids in plywood is where the moisture collects and causes rot. Marine grade plywood is much sturdier.. less give or bending. I would recommend a good epoxy coating to seal out moisture fiberglass resin in not a good covering it will let moisture thru into the plywood.

marine is also usually treated to a higher pressure for longer. it’s worth the cost.

Ck the Menards ads, they have it on sale about every other month. If you only order 1 or 2 sheets they charge a service fee in addition to the plywood price. Good quality wood, they even sandwiched my 3/4″ piece between 2 pieces of 1/4″ plywood for shipping.

I just replaced a floor & built a deck on a 16′ Lund, used the marine plywood, Thompsons water seal & then carpeted.

Thanks for the input guys…made my decision much easier. Looked at Menards online and they do carry it but is special order as STEVENOAK mentioned. Hopefully the “service fee” isn’t too much because I will only be needing 2 sheets if things go as planned. Any suggestions on epoxy coating or something else good to seal it with?

Just a word or caution when putting into a fibreglass hull. Theres usually a foam sandwich between the boat hull and the floor. If the hull is seriously chipped so water can get through without you knowing about it, the foam will soak up (alot) of water and the boat will double in weight. I just replaced a floor in a boat for a friend and he wanted to seal the whole floor and I suggested not to. If you just seal and glass the joints for stability then the rest of the floor will let moisture transfer out of the foam if it does get wet. I remember years back I replaced a floor and when I got down to the foam you literally could pull the foam up and squeeze the water out of it. If moisture gets trapped its bad news. Inspect your boat hull enough to see if its got any chips or cracks in it, or it will take on water. Styrafoam is not water proof, its only temporary, and when exposed to water for any length of time it will soak it up, seen it first hand myself.

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Thanks for the input guys…made my decision much easier. Looked at Menards online and they do carry it but is special order as STEVENOAK mentioned. Hopefully the “service fee” isn’t too much because I will only be needing 2 sheets if things go as planned. Any suggestions on epoxy coating or something else good to seal it with?

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Don’t forget about your local lumber yards Abc,lamperts etc.. they can usually get it next day and not that differnt in price.way easier to deal with to.

Real marine grade ply is some good things but it is not rot proof. Common misconception there.

I had my floor redone in 2007 by Schoenmann Boat Works in Rochester and they recommended putting a fiberglass wrap on the floor, this is something they do on all the new floors they install. If boat companies would do this in the first place we would never have the problem of floors rotting out, after 5 years my floor is still rock solid. For the plywood I ordered it from Lund pre cut to fit and the holes already cut out for my seat bases and yes it was marine grade. Here is the link to that post.

CLICK HERE FOR LINK

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Just a word or caution when putting into a fibreglass hull. Theres usually a foam sandwich between the boat hull and the floor. If the hull is seriously chipped so water can get through without you knowing about it, the foam will soak up (alot) of water and the boat will double in weight. I just replaced a floor in a boat for a friend and he wanted to seal the whole floor and I suggested not to. If you just seal and glass the joints for stability then the rest of the floor will let moisture transfer out of the foam if it does get wet. I remember years back I replaced a floor and when I got down to the foam you literally could pull the foam up and squeeze the water out of it. If moisture gets trapped its bad news. Inspect your boat hull enough to see if its got any chips or cracks in it, or it will take on water. Styrafoam is not water proof, its only temporary, and when exposed to water for any length of time it will soak it up, seen it first hand myself.

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I agree 100% The foam in the boat I refurbished was completely water logged. Tore it all out & replaced with the “pour in foam” leaving a channel down the center for drainage. A couple boat dealers advised me NOT to fiberglass the floor, just make sure it drys out after getting wet. Any screw hole or crack in the glass that is not completely sealed will allow moisture in & it will not dry out.

Draw up a visual image of the bottom of the boat hull, the foam inbetween and a glassed floor. Imagine a crack or a couple chips from hitting rocks etc. The water gets in through those places and the foam does soak it up, get in contact with any boat dealer that has done enough repair work to know what happens. If the floor is sealed there is no place for the water to transfer out of, drying the foam or limiting its evaporation. The floor I did years ago was so bad and the styrafoam so decomposed that all you had to do was grab it by your hand and pull it from the foam in the hull. All you had to do was squeeze the foam and water ran from between your fingers, it was totally waterlogged.

Sealing the floor is a good way to keep rainwater from getting through the top and water logging the foam but it doesn’t solve the problem of water coming up through any cracks or chips in the hull. If the foam does start soaking up water, and it will, where is it supposed to evaporate out of besides the cracks and chips that it came through in, and that would be very limited.

Like said above if there is a trough and an exit opening to keep it vented, so if the hull does have cracks in it, the water has a place to evaporate out of. You can cut a trough down the center removing the center foam and make a small exit, maybe a 6″ by 4″ in the rear plywood infront of the motor so water can transfer and keep the foam realitively dry, this is the only way Id do it is if the foam has a place to dry from.

It’s important to NOT seal the floor to the outside hull. It should be left open to allow air to circulate between the side walls and the floor boards.