Marine vs. Wolmanized Plywood

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lcrayne

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I have gotten a variety of opinions on using marine or wolmanized plywood to replace a boat floor. My understanding is as follows: Marine plywood is stronger, more water resistent and holds fiber glass resin better. While wolmanized plywood is about one/half the cost, its is not as water resistent (being treated only for insects)and has voids which may affect the strength. West Marine sells something they call Boaters Resin which they maintain is adequate to coat the bottom and top of the new floor without the need for fiber glass cloth. Plan to use stainless steel screws to join the new floor to the lip of the old floor and the stringers which will require spacers that will get resin on both sides. To join the new floor to the sides, they recommend something called 5200 caulking. Since I only need three sheets of plywood, the extra cost is not a factor. I plan to use the marine plywood. Anyone see anything wrong with this plan?
 
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Columbia

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Re: Marine vs. Wolmanized Plywood

I'd use the marine ply of the two mentioned but mostly because I'm not sure that Wolmanized wood will hold resin or caulk. Someone's probly done that and knows.... I can't comment on the rest, really. Each job has it's own requirements but you definitely want structural integrity when you're done both for wear and waterproofness so you don't have to do it again in five years....
 
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paragod

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Nov 23, 2003
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Re: Marine vs. Wolmanized Plywood

:eek: well I can say that wolminized willnot hold epoxy about a month in texas sun and you will have a nice mold of what ever you tried to make
 
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plywoody

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Re: Marine vs. Wolmanized Plywood

Marine plywood is very strong, and durable. But it is not "water resistant" If you want it to last a long time, seal in in epoxy or something that will keep the water away from it. It is crucial to keep it dry, as it will swell if it gets wet, and shear the bond between any expoxy and the wood.
 
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lcrayne

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Re: Marine vs. Wolmanized Plywood

Is there any thing that is water resistant? Wolmanized plywood? But then I hear it doesn't hold polyester resin or epoxy.
 
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BillP

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Re: Marine vs. Wolmanized Plywood

Wolmanized ply comes in several different grades...including A/C, which is the common marine ply grade. Their pressure treated process uses CCA and the glue is exterior grade...the same glue as marine ply. Wolmanized is as water proof as you can get without coatings and will not rot or delaminate without coatings. If air dried, CCA ply will hold resin and caulking. In theory you could screw it down without painting or any coatings and get 15-30 yrs of life. I don't know anyone who does it this way in a boat but the wood is speced for this service. There are plenty of CCA treated docks around to show it lasts a long, long time when exposed to the elements.
 
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lcrayne

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Re: Marine vs. Wolmanized Plywood

Thanks for the insight. I just bought 3 sheets of AA grade marine ply. Am now thinking I should have got AC wolmanized, or will the marine grade perform as well. Am trying to avoid having to work with glass any more than absolutely necessary.
 
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Columbia

Petty Officer 2nd Class
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Messages
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Re: Marine vs. Wolmanized Plywood

My experience is the common marine ply grade is A/B, not A/C. The B face is plug filled rather than leaving voids as the C face would have. If you can get a piece of the Wolmanized wood and try resins on it for a test, it is what I would do.
 
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BillP

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Re: Marine vs. Wolmanized Plywood

bourbon, <br />If you want to ensure a 100% rot proof future then pt ply or composite is the only way. Otherwise just do an A1 sealing job on the marine ply and keep it dry. <br /><br />If you do research it will be found that cca treated ply has no problems with resin sticking to it. Most people who contradict this are thinking about the old treatment ways (20+ yrs ago)that used a petroleum based process. The key with cca ply is having low moisture content. This can be accomplished by air drying regular pt ply or buying marine pt ply, which is dried at the factory after the treatment. Greenwood Products is one of the manufacturers of marine pt ply if you need a source...it costs more than regular marine ply.<br /><br />I've done my own shade tree testing with cheap HomeDepot pt ply and epoxy...I couldn't get it to peel without taking chunks of wood with it and I used a chisel to dig under the epoxy to start the peel. I beat it with a 10lb sledge hammer and it destroyed the wood, not the bond. Also, like sailorman says, most marine ply I've seen is AB but the Wolmanized org posts that AC is the common grade. I figure they know more than me on what is consumed. Either way, modern ply is much better than it was 30 yrs ago...the voids are smaller and fewer no matter what grade you use.
 
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