Plywood - is this stuff ok?

[ako]

As it says, what would this plywood be like?

Everything I read mentions AC and AB grade, or marine grade. I think the WPB glue is ok, but don't know if this ply is suitable.

Sorry if this seems like a stupid question, but nobody I have talked to that sells ply can be of assistance. I live in Dubai by the way, if anyone has any details of a good supplier in the area.

I am looking at building my first boat, maybe a 14' dingy or something similar. I know the 18mm ply is too thick for this, but that's all I could get a photo of.

Thanks

[alan white]

Oh good... they damaged a few pieces. Get a free sample and boil it for a while and see if it delaminates or does anything strange. It is one way to see if the ply is boatworthy. Another is voids in the inner plies. Maybe purchasing a whole damaged sheet for a big discount would allow some investigation?

Alan

[marshmat]

Everything I read mentions AC and AB grade, or marine grade.

Marine is of course the best. Of the exterior grades, AC is preferable to AB, at least in the thinner sheets. The reason is that with AC, the worst veneer is on the outside where you can see and patch it, while the inner plies tend to be more solid. AB has the exact same crappy layer as AC, but now it's on the inside where you can't tell where the knots and voids are.

I think the WPB glue is ok, but don't know if this ply is suitable.

Take Alan's advice and get a small piece, or one sheet. Cut it up. Check for voids, holes, knots and cracks in the middle. Put a piece in a pot of water, bring to a near boil, and simmer for the better part of a day. If this doesn't delaminate or warp it, odds are the glue's waterproof enough for ya.

Sorry if this seems like a stupid question, but nobody I have talked to that sells ply can be of assistance.

There's no such thing as a stupid question. Indeed, yours is considerably more complicated than it might appear at first. And don't expect the salespeople to understand- remember, they're selling the stuff as subfloor panelling, not as boat hull.

[Pericles]

Were I to consider building a number of boats with Marine Ply and the MP be not available where I live, would I move? Absolutely! It is just not possible to make a silk purse out of a ---.- ear.

On the other hand, with glass fibre cloth and epoxy resin to keep the water from the wood, the one boat you want to build, will be good experience and should serve you well enough. It must be epoxy and not polyester, or you'll take an early swim.

Pericles

[marshmat]

It must be epoxy and not polyester, or you'll take an early swim

I wouldn't be quite so harsh on poly as to say it must be epoxy... my current boat is polyester/fibreglass over plywood and is holding up just fine. But it's a trailer boat that rarely sees rough weather. Epoxy's a lot stronger, more waterproof, and easier to use, and will bond better to the wood. I do highly recommend using epoxy instead of poly, but that's not to say the latter won't work at all- only that it's a lot harder to get it to work OK, and won't be as durable when it does work.

[Pericles]

Matt,

If you accept that epoxy does a better job, then those attributes will make up for the deficient ply available to ako in the UAE. The other side of the equation is that using top grade marine ply and polyester would result in a worse boat than if epoxy resin were used. My conclusion is that boats should be built with the very best materials, but epoxy is vital even if the hull were constructed with newsprint and egg boxes. Joubert and West will gain Lloyds approval.

Pericles

[PAR]

As a general rule, hull shell materials should be the best your budget can manage. Typically, the hull planking is the best wood on the boat, for obvious reasons.