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X-Shark · 12-20-2008, 09:14 AM

Hmmmmmm!

First the only place to get "Marine Plywood which is A-B Fir, is Meridith Lumber. They stock 3/8in,1/2in & 3/4in.

Now Pine plywood is heavier. Birch or cabinet grade plywood will rot much faster, but when it is encapsulated and all moisture is kept from it, it will work but not recommended for any boat.

Contrary to what a "Building supply" store tells you PT [pressure treated plywood is NOT Marine plywood. It is just PT Pine plywood.

Remember Pine is heavier than Fir.

Now Fir plywood will "Check" if it doesn't have a layer of glass on it. It can be a very light layer. [4oz or 6oz fiberglass] will stop it from checking.

What is Checking?

Here is a example of Marine Plywood that has been Epoxy resign coated only. [no glass] It has Awlgrip 545 primer on it and PPG Concept paint. It sits in the weather full time and no attention is payed to it. This was a experiment many years ago.

Note the little cracks across the Black background. That is Checking.

There are other types om Marine plywood and they are actually better than Fir. They are not available local and are more expensive.

So shippung will eat your lunch. They are Okume Marine BS1088 & Meranti Marine BS1088.

They will not check and will do fine with just a resin coat.

A coat of oil based paint will still let the AB Fir Marine plywood still Check.

There is one PT Plywood designed for boat work.

http://www.greenwoodproducts.com/xlpanels.htm

It is treated and then put back in the Kiln to dry it to XYZ moisture content. Resign will stick to it. I have never used it and don't know where to get it.

I hope this gives you a better education on "Marine Plywood"?

I've come behind a lot of people and seen what skimping and standard practices does.

12-20-2008, 09:14 AM	#4
X-Shark Senior Member White Marlin Join Date: Oct 2007 Location: Pensacola, Fl. Posts: 3,030	RE: marine grade plywood Hmmmmmm! First the only place to get "Marine Plywood which is A-B Fir, is Meridith Lumber. They stock 3/8in,1/2in & 3/4in. Now Pine plywood is heavier. Birch or cabinet grade plywood will rot much faster, but when it is encapsulated and all moisture is kept from it, it will work but not recommended for any boat. Contrary to what a "Building supply" store tells you PT [pressure treated plywood is NOT Marine plywood. It is just PT Pine plywood. Remember Pine is heavier than Fir. Now Fir plywood will "Check" if it doesn't have a layer of glass on it. It can be a very light layer. [4oz or 6oz fiberglass] will stop it from checking. What is Checking? Here is a example of Marine Plywood that has been Epoxy resign coated only. [no glass] It has Awlgrip 545 primer on it and PPG Concept paint. It sits in the weather full time and no attention is payed to it. This was a experiment many years ago. Note the little cracks across the Black background. That is Checking. There are other types om Marine plywood and they are actually better than Fir. They are not available local and are more expensive. So shippung will eat your lunch. They are Okume Marine BS1088 & Meranti Marine BS1088. They will not check and will do fine with just a resin coat. A coat of oil based paint will still let the AB Fir Marine plywood still Check. There is one PT Plywood designed for boat work. http://www.greenwoodproducts.com/xlpanels.htm It is treated and then put back in the Kiln to dry it to XYZ moisture content. Resign will stick to it. I have never used it and don't know where to get it. I hope this gives you a better education on "Marine Plywood"? I've come behind a lot of people and seen what skimping and standard practices does.