Marine Plywood

[Fish killer]

I have to repace the floor in my 16' Bluefin, and so in the process on tearing it out I found that my transom is rotten too. So I tore that apart also. Now on to the question. What kind of plywood to use? My brother suggested wolmanixed for the floor. But what about the transom? Anybody have any ideas? I am guessing marine grade plywood. But where is a good place to get that? Thanks for the help.

[hovermn]

Most Lumber yards carry "marine" grade plywood. Usually, it's a relative of the mahogany family and uses a more water resistant glue. Generally, Marine grade plys will also be cleaner with no voids in the plys and a nice finish on both sides. With that said, I buy marine grade ply from Lake Elmo Lumber. They specialize in unique and exotic woods and haven't let me down yet. After many years, I'm continuely surprised at the performance of their plywood

Another place to try would be Young Blood in Minneapolis. IMO, these two places will be your best bet for high quality woods. Of course, as said before, most lumber yards will carry at least a few choices of marine plys.

[Fish killer]

I talked to Lake Elmo's was scared off by the $150.00 price tag per sheet. Menards can get it, but takes a week. Was looking for someone who has it in stock for have the price

[Wavey Davey]

Rum River Lumber in Coon Rapids stocks marine plywood.

I got some about 2 years ago, at that time a 4' x 8' pc.

was $80 for 3/4" thick and $50 for 1/2" thick.

Options would be treated plywood at half the cost, although

it tends to warp and crack, or just standard exterior grade plywood.

I used 3/4" marine plywood for a pontoon deck and coated it with fiberglass resin. I used green treated plywood for the transom. Both worked out good, should last a long time.

[Surface Tension]

This topic has been covered before. BC plywood coated on all sides with resin makes for a good floor. Something about the new(ACQ-CBA wolmanixed) treated wood. You'll need to use all stainless steel fasteners and not have any contact with aluminum. For your transom it depends on if the transom is sandwiched or one solid piece. If its a solid 1 1/2" I'd suggest getting a hold of some lam-beam. If its two pieces on both sides of aluminum then I'd go with 3/4 marine or BC plywood both sealed.

[hovermn]

Wow, that's quite a chunk of $$$ The stuff I buy is 1/8" ply and it's around $44 a sheet. Guess I should have guessed that 3/4" would be a bit more! lol

As said above, you can use regular plywood with resin to seal it on both sides AND edges. If you go this route, be sure to use Epoxy and not polyester resin. Epoxy has a MUCH higher water resistance then poly resin. On the bottom side, lay down one coat and on top, put at least 2 coats on. The first coat will soak into the wood. The second will fill any voids left by the first.

Depending on the temp, allow around 1 hour between coats. The warmer the temp, the less time you'll have to wait. You want it slightly tacky for the second coat. If you wait too long, you'll no longer get a chemical bond between the two coats and it won't be as resistant to moisture. Also, if left to cure (4-8 hours) before applying additional coats, epoxy will produce a blush on the surface that must be washed off. If you sand without washing the blush off, it'll gum up your sand paper quickly.

Okay, there's my $0.02

[Fish killer]

Are we talking the the good old fashion fiberglass resin? And is that like a epoxy resin? The Transom had two pieces of plywood glue together to make up a inch and a half. I found some marine grade plywood that's treated at Scherer Brothers lumber for $84 a sheet. As far as the floor I am thinking now that regular AB plywood with a coating to help with the moisture is the way I am going to go.

[Wavey Davey]

Standard fiberglass resin is polyester. Epoxy is better if you can find it, bonds better to wood.

[hovermn]

You should be able to find epoxy at most stores that sell boat parts. Cabelas even carries it I believe. West systems my preferred brand, and I've used quite a few. It's consistantly reliable.

Note that you won't need to buy a gal. of resin and quart of hardner. The smaller size resin and hardner containers should be more than enough for what you're doing. Actually, how many sheets are you replacing?

Keep this in mind... Whichever brand you buy, you'll probably have a choice between slow, med. and fast hardners. Buy SLOW hardner. It yields the longest pot life and have more time to soak into the wood giving you a deeper penetrating barrier. It's also best for glassing, too.

[Fish killer]

I have to replace about three sheets 48"x65" and was figuring on about maybe two to three coats. Will I have any problems with gluing down carpet or vinyl(haven't decided which yet)over the epoxy? Also looking to put pedestal seats in and was told to put a sheet of aluminum under plywood for screws to grab and act as a washer. Sounded like a good idea.

[Steve Bakken]

The aluminum sheet is a must. You wouldn't beleive how much stress is applied to that base. We repair dozens of floors each year that have had the seat bases ripped out of the wood.

[hovermn]

You shouldn't have any trouble gluing carpet to the epoxy. Allow around 24 hours before washing and gluing. If it's much below +/- 70 deg. allow around 36 hours. As said before, laminating/fiberglass grade epoxy will blush (wax like coating) when cured. Water and a rag will work. A scotch bright pad would be better. You can even mix in some comet if you'd like. You might think about giving the surface a light sanding with 100-120 grit paper to give the epoxy teeth for the glue to grab onto. Just be sure not to sand through the epoxy.

There are epoxies used for counter tops coating (think bar) that cure clear and hardly blush at all, but these are not structual resins.

LOL, sorry. It's not often I get to chime in as an "expert!" Alright, stepping down from my soap box. LMAO

[Fish killer]

Thanks for the reply with the helpful info guys. Now I have to hit it hard before opener.