K im seriously confused about green treat and marine ply!

[surfman]

Copper is green. The new treatment is far worse than the old treatment, they increased the copper content and removed the arsenic. Anyway it is the copper that is used in the treatment that causes the corrosion. Pontoon boat manufacturers use the old style treatment (CCA old as opposed to ACQ new) on their boats and so does some tin boat manufacturers, If it is insulated from the aluminum it will be fine. I have a Sylvan and the factory used CCA treated plywood in the transom of my boat, they did not insulate the wood from the metal and you can look at my re-build here. https://www.tinboats.net/forum/viewtopic.php?f=3&t=23064
The wood is fine but the metal is not. I would use either marine grade ply or exterior ply and coat it with epoxy, if you use polyester resin you better use glass too because the polyester will just flake off, been there done that.

 

[surfman]

Also if you use epoxy you will need to coat it with varnish or urethane because epoxy doesn't hold up to sun light on its own. Most people put carpet or vinyl or paint the floor with sandy paint afterwards.

 

[Captain Ahab]

For coatings, here is my order...

1. Epoxy Resin. Try West system 105.
2. Vinylesther resin. Cheaper, but not as awesome...mildly awesome.
3. Urethane....doesn't matter what kind.
4 A-Z paint. Too many to mention here.
5. Leave it bare.
.
.
139452. Thompson's or the like.

I agree 100000%

Thompsons is really just parafin wax - and will not last

 

[kbiz]

Used it for my mod also. Def stinks but works.

I had the same concerns. The local boat shop told me that the marine plywood was expensive and I could use pressure treated plywood and cover it with fiberglass and it would work just as good as the marine plywood and also not damage the boat metal.

 

[Ringo Steele]

Also if you use epoxy you will need to coat it with varnish or urethane because epoxy doesn't hold up to sun light well on its own.

I was told the same thing by West Systems when I inquired about their #105 epoxy for my transom rebuild, and was told to apply some form of UV resistant top coating (which I still have to do!). I will probably go with spar urethane for mine, since I like the wood look. West Systems said that it should work for this purpose.

 

[screwballl]

The issue with treated wood is the amount of copper in it, which is what gives it the green color. The more copper, the more it will bleed out and eat away the aluminum on your boat. No matter how thick you add any sealant, the copper will always come through.

https://fourseasonsroofingandsiding.com/mixmetals.htm - this relates to a roof but is the same principle.

Perfect example was a neighbor just down the street from me. He has a 14 ft bass boat and replaced the wooden runners and put water carpet on them. When he checked them the next summer before a trip, the aluminum was pitted and already being eaten away. He had to remove those runners and get marine grade wood that have little to no copper in it. He cleaned up the boat, sealed the problem area and hasn't had a problem since (which has been a year and a half now).

 

[Jdholmes]

The copper is not what turns it green...in fact not all PT is green, it is dark brown in some places.

 

[JamesM56alum]

K so im going to go pick up the ply and sealer this weekend from menards, what ply shold i go with for the floor im thinking 5/8's or 3/4 for the floor and 1/2 for the outside transom, and im going to use the spar urethane from midwax

 

[Jdholmes]

Do 1/2 inch for the floor. With the proper support it is plenty and weighs a heck of a lot less.