Marine grade plywood alternative

[Indiana Rambler]

I am currently looking for an alternative to marine grade plywood. I’m close to skinning the bottom layer of my trailer and I cannot find marine grade plywood within a 50 mile radius. I’m planing on coating the bottom with the asphalt fence post paint for weather/water protection. And direction would certainly be a great help! Thanks in advance.


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[MickinOz]

Not much use to you maybe, but over here we have a thing called structural plywood.

Can be had in pine or some limited sizes in hardwood.
It has the water proof "A-Bond" glue line same as marine plywood, but much lesser quality timber.
No AA face veneers.

CD faces are the norm.
I find the C face can be filled and sanded nice.

The internal layers are not required to be blemish free like in marine grade timber, so definitely second best when it comes to bending it around a curve, or cutting an opening only to find a void where you don't want one.

Should be OK for a flat floor though, if such a material exists in the US.


(Having said that, my next build will feature far more marine ply, and far less structural ply.

This is because I have analysed what went into my build. I have conclud3ed I would have nearly compensated the cost differential by not needing to do so much filling, less work compensating for the lesser dimensional stability, and needing less coats of polyurethane to waterproof the timber.

One thing, I think the stiffer, more dimensionally stable, more warp resistant marine grade available here would better lend itself to making doors from the cut outs. That would save a lot of money.
My two doors cost more than $1300 Australian.)

[ebis]

Consider MDO as a replacement for marine plywood. It is made with waterproof glue and few voids. The MDO that I bought had the kraft-resin layer on one side, and the other side was pre-primed.

[nbcarey]

Consider MDO as a replacement for marine plywood. It is made with waterproof glue and few voids. The MDO that I bought had the kraft-resin layer on one side, and the other side was pre-primed.

MDO was originally designed for highway signage, so designed to have a long lifespan in inclement weather. It takes paint phenomenally well due to the phenolic resin-impregnated paper facings.

[noseoil]

We used 1/8" Baltic birch & white roof coating over 2 coats of urethane, still good & nicer to work under the trailer with a white coating. It's easier to see under there than with the black & it holds up well to road grime, gravel & rain. Marine plywood is fine, but a waste of $ when there are cheaper alternatives.

[ebis]

I think that the price of Baltic birch vs marine plywood vs MDO for the exterior is minor relative to the total build cost. Use MDO if you don't want checking. Use marine plywood if you want 4x8 and Baltic birch if you want 5x5 sheets.