Marine Plywood

[vandy21]

I am in the process of replacing the floors on my boat, and im not sure what type of wood to use. Of course i would like to use marine grade plywood, but i live in central Pennsylvania and there isnt much boating there. Is there anyway to ship it or would it be crazy expensive because of its size? Also is there any other woods that would work well? We have a lot of lumber stores so regular wood isn't a problem. Also would it be possible to have Lowes or a Home Depot type place order this wood?

 

[Robj]

Re: Marine Plywood

Hello there,

I used exterior grade 1/2 inch Douglas Fir plywood for my floor. Marine grade costs about 3 to 4 times as much as exterior grade. Hard to justify the cost when the regular exterior grade ply is all you need.

Have a great day,

Rob.

 

[reelfishin]

Re: Marine Plywood

I've done several with plain old exterior plywood and all have lasted many years, most have now lasted far longer than the original floors did. I am not sure if all of the manufacturers use marine grade plywood, the soggy mess I cut out of my last project was only a few years old, if it was marine plywood, it sure didn't last very well.
Just avoid using carpet and seal whatever plywood you use well with resin on all sides. The trick is to completely keep it from getting wet. They also make presure treated plywood, but that is heavy, and tends to be too wet and don't make good solid floors like common outdoor fir plywood does. Depending on the boat, I also often go a little thicker too, it makes for a more solid feeling floor.
Avoid carpet if you can, it only causes rot and holds moisture.

 

[rost495]

Re: Marine Plywood

I understand the resin will not attach to treated plywood so treated is out the window. That was the answer I got about it in the early 80s and still what I hear...

Jeff

 

[Coors]

Re: Marine Plywood

Resin will stick, but you have to let the pt ply dry out first.

 

[Robj]

Re: Marine Plywood

On my floor I put matt on both sides to seal it up, 1/2 inch thick was plenty, floor is solid. If I were to do it again, I would even consider going with 3/8 ply,when you glass it is really stiffens it up. When you install the ply, make sure that the grains of the outer layers of the plywood are running perpendicular to the stringers.

Have a great day,

Rob.

 

[brodie6]

Re: Marine Plywood

The real advantage to Marine plywood as I see it is that it is kiln dried not layed out in the yard to soak up moisture like the H.D. wood. I just used Marine and it was bone dry. It would take months to dry out the H.D. stuff if you wanted to do it right. I think it's worth the added expense. Unless of course you like ripping up the floors

 

[drewpster]

Re: Marine Plywood

I have also heard that high quality marine grade plywood is void free. Meaning there are no voids inside the lamination. This avoids micro environments that can produce condensation and subsequent soaking of the wood over time. Personally I think the newer core materials are better to invest in if you want to build a boat that lasts longer. However the cost would be too great for the return in my opinion, assuming the composite cores are far more expensive than marine ply.
I do know that the new boats I have looked at using these composite cores are very ...very expensive

 

[John_S]

Re: Marine Plywood

Exterior plywood should be fine for floors. Not sure if you are doing a fiberglass or alum boat floor. On our '67 Starcraft (alum) the original floors lasted 30+ years. When I removed it, found it was ext plywood, not marine. It was not even painted on the underside! The floor rot we had, I'd say was more caused by the water logged foam holding the moisture in contact with the wood. I used 5/8" ext plywood, one side sanded, for the replacement. I did seal and paint all sides.

 

[reelfishin]

Re: Marine Plywood

I have a 1973 Starcraft that also has non marine plywood floors, I had to pull up a section fo floor last year to repair a loose cross brace, but resused the original floor, it was in perfect shape with no rot. The lower side was uncoated, and the top is covered in a thin layer of glass and resin. The top coating is so thin you can read the writing on the wood from where they marked the pattern. It was also carpeted for all these years. It's been stored outdoors with a tarp over it as long as I have had it.
I replaced the floor in one of my old boats and used just good quality exterior 5/8" plywood and a buddy still uses that boat to this day, that's been 12 or more years ago and it gets stored outside with no cover most of the time. I pre coated each sheet after cutting them to fit with resin, sealed all seams with resin and glassed over the entire top. I also epoxy coated the top surface with standard garage floor epoxy that I had left over from work. He since has had the interior sprayed with Rhino Liner to make it more wash down friendly and less slippery when wet.

 

[Coors]

Re: Marine Plywood

Marine ply (with no voids) is mainly needed when bending around a curve, so as not to crack at a void. Like on a hull.

 

[reelfishin]

Re: Marine Plywood

Marine ply (with no voids) is mainly needed when bending around a curve, so as not to crack at a void. Like on a hull.

That makes sense to me, I had an old Owens that had a marine plywood hull, I can see the benifits of that there, but I never saw the need for it on floors, especially if it's protected or coated well.

 

[hrzracr23]

Re: Marine Plywood

my two cents having just done my floor I went to goood ol home depot and got half inch pressure treated which you are all right is heavy and wet BUT, I asked the paint attendent what would work to clean/dry out/ prep the wood so the epoxy and other products would adhere nicely and low and behold there is a product you cut in with water its a detergent kind of thing that washes the wood takes the green out and the sapyness but doesnt mess up the treatment of the wood worked like a charm washed it down with that stuff and put it out to dry the next day it was much better and easy to work with but thats just my two cents

 

[DillyDally]

Re: Marine Plywood

Try to find Plydek from Greenwood Products at a pontoon dealership, like Bentley or such. I paid $70 per sheet for CCA treated 3/4 9ply which is a good deal for such wood. Also, it takes fiberglass mat.

 

[byrdman64]

Re: Marine Plywood

I have a little tip for plywood hunters, I live in south Mississippi and the Guys around here found the best place in the world to buy marine plywood.
We found a small concrete form company that builds forms for the Highway department for like over passes and bridges. they use Marine Grade plywood and rebuild their forms every few months so a endless supply of 2x2, 2x3, 4x4, 4x6, and even 4x8 you name it they have it.
I bought a trailer load for 75 bucks enough to build 4 shooting houses and floor my new 16 x 20 storage shed. I bet if you guys check around you have one near you too! beats 70 to 100 per sheet new.

 

[Coors]

Re: Marine Plywood

That is probably plyform; is it oily?