Is this "Marine Plywood?"

[kryan2]

It's 1/2 inch. Previous owner said it was changed out 13 months ago.

???????

 

[tylerjake]

I'm not a expert but I wouldn't say so

 

[JDA1975]

Re: Is this "Marine Plywood?"

without any type of water barrier, even marine ply can get bad! its wood and water still.

 

[jigngrub]

Re: Is this "Marine Plywood?"

Lemme guess, you pulled the carpet up because the deck felt spongy... right?

With the big center cores like that I think it is, but it was poorly installed and has gotten water damage on both sides. Both side should've been sealed with epoxy resin or polyester resin and glass cloth for installation on a pontoon like that.

Not only was it poorly installed, but it was a poor choice in the thickness too, 'toons should have 3/4" decking.

You should throw that crap away and go buy some 3/4" ACX and install it properly.

 

[bonz_d]

Re: Is this "Marine Plywood?"

No expert either but I always thought marine ply had at least 5 thin plies or more.

 

[Cadwelder]

Re: Is this "Marine Plywood?"

Doesn't look like any marine grade I've ever seen.

 

[Cadwelder]

Re: Is this "Marine Plywood?"

Here a picture of a fillet I made as a sample...this is Douglas Fir marine grade plywood.

 

[Gun Dog]

Re: Is this "Marine Plywood?"

At this point it doesn't make a difference. It looks shot. Unless the PO claimed it was marine grade and would give you a refund if it wasn't. All plywood imported to this country is required to be graded and stamped. The stamp is usually rolled on the "B" side if its construction or on the edges if its cabinet grade.

 

[kfa4303]

Re: Is this "Marine Plywood?"

Hi kryan2. It very well could be Marine Grade. As per a previous post, unless the wood is waterproofed in some way it can/will rot in time. Marine Grade plywood isn't really special in any way, except that it has no (much fewer) voids within it, than regular plywood, and is therefore more solid for a given thickness. It looks like the deck is attached to aluminum stringers, in which you cannot use pressure treated wood to replace the rotten deck, tempting though it may be, as it will have an electrolytic reaction between the aluminum and the copper/arsenic used to pressure treat the lumber. You'll want to get 3/4" marine grade plywood, if possible, or exterior grade non-treated wood, and treat it with either Epoxy, or Polyester Resin and fiberglass. The epoxy process is a little quicker, but a bit more expensive. There are tons of threads here in the restoration forums that can walk you through the process. It's not that bad. If you do it right, your grand kids will still be using the boat. Keep us posted. Good luck.

 

[bonz_d]

Re: Is this "Marine Plywood?"

As I recall also, back in the old days before fiberglass much of the ply that was used in building boats was made from Mahogany.

Those old boats were made in panels and frames or Lapstrake cut boards and the funny thing is that none of them had any fiberglass on them and they also lasted for years! All one has to do is look at the number of Thompsons, Cruisers Inc, and others of the Lapstrake build hulls that are still floating today, some well over 50 years old!

 

[gonagin]

Re: Is this "Marine Plywood?"

Nope!!!

 

[drakus]

Re: Is this "Marine Plywood?"

marine plywood is generally 7 plys, but can be 5 plys for smaller thicknesses

 

[BWT]

Re: Is this "Marine Plywood?"

No way that's marine grade. The "marine grade" rating is something that's gotten muddled over the past few years; there are "variations" that some people claim to be marine grade, but in order to be "certified marine" it need to have a BS1088 or BS6566 rating (BS standing for British standard). This is a rating that is given by Loyd's of London and is guaranteed to be void free, solid (rot resistant) wood every ply and laminated with WBP (water and boil proof) glue. Menards carries ply that is not technically certified marine, but the ply's are thin and numerous for the respective overall thickness of the ply and are laminated with WBP glue (this is stamped on the lower corner). BUT, when I am looking for true marine ply, I buy okoume ply with a BS1088 rating. The ply in your pic looks more like standard exterior grade (NOT marine) The ply's are too thick.

 

[MTboatguy]

Re: Is this "Marine Plywood?"

Nope!!!

I was going to say the SAME exact thing...I guess I will anyway..

Nope!

 

[fishrdan]

Re: Is this "Marine Plywood?"

Looks like cheap exterior ply to me.

in order to be "certified marine" it need to have a BS1088 or BS6566 rating (BS standing for British standard). This is a rating that is given by Loyd's of London and is guaranteed to be void free, solid (rot resistant) wood every ply and laminated with WBP (water and boil proof) glue.

Are you suggesting that the OP use the Lloyds of London certified ply for his toon There are many types of marine plywood to fill different needs and price ranges. The OP should get CCA treated pontoon decking (type of "marine plywood") as it's designed for pontoon boats and water exposure.

The other option would be to use a good grade of plywood, like 5 ply exterior 1/2" plywood, and encapsulate it with epoxy, poly resin and glass, or on the cheap (but not recommended) oil based paint like Rustoleum. But, with the additional cost of materials, added time and labor, it could be better to just use pontoon decking. Depends if you can get the toon decking locally, shipping the toon decking would be cost prohibitive.

 

[Sea18Horse]

Re: Is this "Marine Plywood?"

Yeah the mahogany marine ply I got for my little project was nine plies in the 1/2 inch sheet and five plies in the 1/4 inch sheet. I gotta say that is some seriously nasty stuff to work with. Even though my dads workshop has a central vacuum system going to all the different equipment, even a small cut on the table saw creates a cloud of mustard gas-like dust. And the portable 12'' planer didn't like it one bit!

Cheers...................Todd

 

[BWT]

Re: Is this "Marine Plywood?"

not telling anyone what to use; that's your choice based upon availability, money and intended use. Only explaining what "true" marine grade is and how it is rated. Yes there are ways to properly treat non marine grade wood for cost savings and there is nothing wrong with that as long as it's done correctly. But to be clear, there aren't "many grades" of marine ply; only a couple. The others are knock off's that may be acceptable if treated properly, but are not true marine grade.

 

[Gun Dog]

Re: Is this "Marine Plywood?"

Yeah the mahogany marine ply I got for my little project was nine plies in the 1/2 inch sheet and five plies in the 1/4 inch sheet. I gotta say that is some seriously nasty stuff to work with. Even though my dads workshop has a central vacuum system going to all the different equipment, even a small cut on the table saw creates a cloud of mustard gas-like dust. And the portable 12'' planer didn't like it one bit!

Cheers...................Todd

Putting plywood through the planer???? Better stay out of dads shop.

 

[JimS123]

Re: Is this "Marine Plywood?"

As I recall also, back in the old days before fiberglass much of the ply that was used in building boats was made from Mahogany.

Those old boats were made in panels and frames or Lapstrake cut boards and the funny thing is that none of them had any fiberglass on them and they also lasted for years! All one has to do is look at the number of Thompsons, Cruisers Inc, and others of the Lapstrake build hulls that are still floating today, some well over 50 years old!

Back in the day marine grade fir plywood was what was used. The classic lapstrake utilities only used mahogany for the decks.

The "important" difference between construction grade and marine plywood is the type of glue used. Marine grade uses a resin glue that is waterproof. It will still rot if not sealed, but delamination is less likely. Due to the poor conditon of the wood in the pics above, I would say that it IS marine grade because its still together.