Pontoon Boat & Deck Boat Forum

Plywood finally showed up today but looks like plain wood ,is it supposed to be stamped marine anywhere just looks like a,b 7 layer

Who did you get it from ?, it is not stamped, the main differance is the glue used to put them together and it does have a little darker look then regular ply

You should be able to count the plies of the plywood.

I would think it would have a marking of some sort on one side.

I may be way off but its my understanding marine ply has 7 layers and regular has 5.

MH Hawker wrote:I may be way off but its my understanding marine ply has 7 layers and regular has 5.

DING DING DING!! We have a winner!
Marine ply uses water-resistant glues and has 7 plies versus 5 in usual ply.

It should be absolutely faultless as well - NO voids, knots, "biscuits" nothing. Perfect on BOTH sides.

RonKMiller wrote:It should be absolutely faultless as well - NO voids, knots, "biscuits" nothing. Perfect on BOTH sides.

it is A,B side with the voids fixed on the A side

So a side up or down ....lumber yard also told me I should put sealer on it

clownin wrote:So a side up or down ....lumber yard also told me I should put sealer on it

Sorry I was wrong, B/C is used on pontoons, B side up so you don't end up wearing holes in your flooring, you shouldn't have to treat it but it won't hurt.

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.

Another clue is that Marine Grade is usually much heavier than standard plywood due to the amount of glue used to make it even tougher.

Ok biscuits down ..think I might just go with a coat of Thompson or something for extra protection

Mine has biscuits on top to fill voids, so biscuits up, but you should be able to tell which side is better, no holes or voids at all.

I can't remember where I sourced mine, but it was flawless on both sides, 100% Meranti including the cores, and kiln dried. I seem to remember paying about $70.00 a sheet. Since it is so much stronger than regular plywood I was able to go with 1/2" instead of the typical 3/4". The weight savings is significant considering I've got a 224 sq. ft. deck. (8' X 28') The shipping was $$.

It had a round stamp on each sheet denoting it was BS1088 compliant. http://en.wikipedia.org/wiki/BS_1088
"Occasional gaps may be repaired using veneer inserts (biscuits) bonded with the proper adhesive as well as "sound pin" defects: A small knot with a diameter of 0.5 inch (1.3 centimeters) or less, but only so many over a specified area."

Mine also had no "sound pin" knots or I would have rejected it.

The deck was about the ONLY thing on my boat where I went for extremely high quality. It's a project I never want to do again. I was after serious structural integrity considering it is a tension stressed member in my build - much more than just a floor.

There are few international standards for grading marine plywood and most of the standards are voluntary. I think the term "marine plywood" is thrown around pretty loosely - and certainly there are many suppliers that produce inferior products claiming them to be the "real deal" ...

clownin wrote:Ok biscuits down ..think I might just go with a coat of Thompson or something for extra protection

That would be totally inadequate, sorry. You'll need multiple coats of epoxy, high quality marine paint with a primer base, or a rubberized, elastomeric coating in order to protect it.

RonKMiller wrote:

clownin wrote:Ok biscuits down ..think I might just go with a coat of Thompson or something for extra protection

That would be totally inadequate, sorry. You'll need multiple coats of epoxy, high quality marine paint with a primer base, or a rubberized, elastomeric coating in order to protect it.

You only need that if you make a wood boat and the wood is sitting in water and below water