Plywood to use for floor

[Todd Peterson]

I have to fix the floor in my 1984 Beretta. What type of plywood do I need to use and how long does the hardner take to check hardness?

 

[Chris1956]

Re: Plywood to use for floor

Todd, You post was incomplete. I will assume that you have a bad section of floor in a conventional fiberglass boat with a floor made of glass and plywood. If so, you need to cut back the existing floor until you find good plywood, and something(stringers, frames..) to fasten the new plywood to. You then cut the new plywood to size and screw it to the support members. You must then sand the old floor fiberglass to feather it whereever adjacent to the repair. Now mix up some polyester resin and hardener, paint the feathered area and the new plywood and lay cloth over the resin. Now saturate the cloth with resin, and add a second layer of cloth, if the cloth is light.

I use dry pressure treated 1/2 plywood for my repairs and well as stainless steel wood screws to attach the new section of plywood. You can fill between the plywood seams with some marine polyester putty. Make sure the foam floatation under the floor is dry.

 

[fishingdan]

Re: Plywood to use for floor

True dry pressure treated is hard to find these days and it needs to be dry before anything will stick to it well.

My preference is do everything as noted above except, use standard external (ACX grade can be fine) and use epoxy instead of poly resin. Unless you use higher grades of poly resin (a good vinylester for example), water will eventually work its way in. 2 or 3 good coats of epoxy on the wood to seal it.

Either way, the repaird floor will last a very long time.

 

[Chris1956]

Re: Plywood to use for floor

Dan, Epoxy resin on a boat floor is overkill. Two layers of cloth and poly resin will be waterproof and sufficiently abraison proof, and cost a whole lot less. Epoxy resin is only needed in high strength repairs like stess cracks and holes in the hull, IMHO.

You can use the AC plywood if you want, however, everyone puts screws into the plywood floor to install seats and other things, and they don't waterproof them sufficiently. This will cause the AC plywood to rot sooner than the PT plywood.

 

[oops!]

Re: Plywood to use for floor

Dan, Epoxy resin on a boat floor is overkill. Two layers of cloth and poly resin will be waterproof and sufficiently abraison proof, and cost a whole lot less. Epoxy resin is only needed in high strength repairs

chris......where have you been when i been fighting the poly vs epoxy battles?

im in agreement with pt ply.....however it takes over a month in controlled situations to dry it properly........(no....it isnt dry off the shelf)

if you have time......pt ply.....(use the correct screws)....if you dont....standard exterior grade ply will do.......if done correctly....each method will last over 20 years.....

(glass the bottom of the floor too......waxed on that side)

cheers
oops

 

[Todd Peterson]

Re: Plywood to use for floor

I just completed replacing stringers, motor mount and floor of my 22 foot Baretta. I used 3/4 inch exterior grade plywood stringers with West System epoxy and #6 fiberglass mesh. I used 1 1/2 gallons of West System epoxy (that was expensive). I then screwed green treated (pressure treated w/copper) 1"x1" strips flush with the top of the stringers to screw the floor in. I do not want to screw into the end grain of the plywood. Then I foamed the floor with USCompanies foam in between the stringers. I only got about 1/2 of the coverage of the foam and it was 82 degrees. Then I used poly resin to treat the green treated nailers and the green treated lumber around the gas tank.
I used 1/2 green treated plywood for the floor that I treated with poly resin but used West System epoxy to secure the floor to the side walls and the stern. I used deck screws to secure the floor to the green treated plywood. I have build houses for many years and build many decks and I do not have a concern with deck screws and green treated lumber because that is what you use on your deck...
I treated the floor with poly resin to cover all screw heads.
Next is carpet and seats. Then...winterize, it is getting colder in MN.