Plywood for floor

[activator22]

I need to put down a new floor in my Activator, existing floor had rotted around seat mounts and had to be cut out for gas tank replacement - My question is is there any sense spending the extra money to get marine ply as opposed to using exterior grade ?

I know the marine ply has more plys and no voids, strength and cosmetics are not an issue in this - I'm planning to use 1/2", sealed with epoxy all around, with 4 oz glass top and bottom. I was told the glue is basically the same.

Thanks

[Liqui-Fly]

Me personally...I'd go right to Home Depot and have at it. Especially if you are going to seal it. Have you ever thought about foam? If you are sealing it I would stay away from the exterior crap too. It tends to be wet and the epoxy will not bond and seal as well.

David

[Techno]

Just about all plywood uses the same "waterproof" glue so you can use any of them. If you don't care about the wieght and voids skip the skinning and soaking. The floor will last a while with just paint. Seal any holes you put into it like the seat mounts.

After a while the floor will start to go soft. Just replace it.

[Georgia Boy]

I have to disagree with you, not all plywood has the same glue, that is what separates it in some cases. I know interior plywood well delaminate if a good dew hits it. does not take much moisture for it and it should never be used in a boat, but I have used exterior grade CDX and it holds up well for a floor. The reason i tried the interior is I have a friend who works in a plywood plant and that is what they made, so i got it for free, but it would not hold up. i had to replace a floor one in the period of three months when i used it once. after asking him he said the glue just will not hold when moisture hits it.

[activator22]

I considered foam (Airex and Klegecell) and basa core, but need to mount seats, foot throttle to the floor and have heard you really should have plywoodwood (either as the floor as under the foam) to bolt up to. I am also a novice when it comes to knowing how thick the layup needs to be on both sides of the foam - I did order a 2'x4' of Balsa core from FGCI to make a cooler/storage top that will end up in the middle of floor, in front of the seats in a no load area - I was thinking of doing a layup of mat and 6 oz cloth on each side, does that sound like enough skin or overkill ?

I built a center console seat out of interior ply on my previous boat, and sealed it with epoxy, but the glue on those plys was not waterproof and just the humidity eventually caused the plys to seperate after 4 years

[vector mike]

When ever I use plywood for repairs I always mix up some fiberglass resin and just brush it over the entire surface. It seals it watertight and will not seperate from moisture.

[Liqui-Fly]

Their web page has a chart that shows how much more strength you get each additional layer you put on. It's exponential. So maybe laying 2 layer of 1 oz would better better than 1-4 oz layer. Make some test panels and see.

David

[pyro]

I've said it before and I'll say it again, www.rotdoctor.com
Get their CPES resin, it's water-thin and it penetrates all the way through the wood, preserves it forever, even if you do sloppy woodscrewing into it. All other resins will stick better to wood that has been treated with the stuff.

I had an exposed edge of plywood floor at the back edge of my ski locker, the floor was still solid, but was flexing a tiny bit from the exposure. I soaked several ounces of CPES resin into the edge of the ply, and after 3 applications, the floor is rock-hard in that same area and will NEVER rot!

Hasn't anyone else used this stuff? It's expensive but GOOD.

[Tony Brucato]

If you figure out what your time is worth for replacing the floor plus other material to bond and seal the floor, You'll see that the cost of a GOOD grade of marine plywood is a fraction of the total job. Kind of like cheap paint vs. quality paint.
Not all Marine plywood is created equal. I tried some "marine" plywood that I bought from home depot and it wasn't much better than CDX. The best stuff is Okume (sp?) brand. It's a much stronger and lighter plywood than what you'll find at the builder's supply center.

Tony

[Liqui-Fly]

A floor of Okume can cost more than some of us have payed for our resto boats.

David

[Tony Brucato]

$96 per 4X8 sheet of 12mm (1/2). Just how big is your boat?

[Liqui-Fly]

I guess that isn't bad at all. I was looking at the stuff before I think on Seebolds web page cause I was gonna build a little tunnel and I got sticker shock. Where do you get it from?

David

[Tony Brucato]

I buy mine from http://www.worldpanel.com/
They sell mostly mail order. Lucky for me that they are right down the street.
Check their website. Lots of good information and new products.

Tony

[Liqui-Fly]

How's the weight compared to regular plywodd and would you still suggest laminating it?

David

[Tony Brucato]

I just paint epoxy resin on both sides and edges to seal, and 6" wide cloth at all joints. That seems to be good for up to a 16" span between supports. It weighs about 1.2 pounds per sq. foot.

Tony

[Liqui-Fly]

Could end up saving on resin and glass by going that route.

David

[Techno]

If your going to use an expensive form of plywood and coat it and glass it then skip all that and get foam. You coat it with cheaper poly resin and still glass it. Why go to all the trouble with plywood? The attachments aren't that big a deal, almost balances out compared to sealing the holes in the ply. I found the use of top hat stiffeners to work better than the foamed in ridges I used. Make a mold and run as many as you want.

Haven't tested the fasteners bonded in the floor but for them to fail they will carry a strip of floor 14" long and about 2" wide x 1" deep, for one side. The floor for them was increased to 1" so its 4 x as strong as the 1/2" floor. I don't think much below a pterodactyl hit is going to rip them out.

Theres a few pictures of limited value on my site with the foam floor. I think its roughly half the weight of a ply floor. I think it was about 2 gallons of poly resin, but I started getting sloppy too. Floor is about 4'x7' and is only supported at the sides, nothing in the middle. A lot of boats out there have some kind of joist system underneath to support the floor. With that its easier.
You could also put the sections in the boat and join them, I was able to slide the completed floor in place.
foam floor (http://members.lycos.co.uk/technostv/photoalbum4.html)

[Tony Brucato]

I'm adding that to my favorites.
Nice work!

[JamesE]

The floor in my Bullet is sandwhiched Kledgecell and I am pretty impressed with it. The boat is a 1990 model and the floor is in perfect shape. The 1988 model I had was the same and when I pulled the floor out for the restoration project it was in such good shape that I ended up resealin the stringers and reusing the same floor. I personally will never put wood in a floor again.

[H2Onut]

ALL THE WAY, a sheet of 4x8 was 89.00 Kleg 75
Sheet its about 1/10 the weight of plywood. I usd it andy 3:1 epoxy. bulletproof, waterproof and light. ALso easy to cust and form compound curves and edges.

[activator22]

Regarding Klegecell - how thick does the glass layup need to be on each side - Also, how is the hardware such as seat mounts, foot throttles etc fastened - I don't have a lot of experience with it on power boats, but on all the rag boats I have worked on, builders either glassed in plywood in the area where thru bolting was done, or used large backing plates..

How are you guys getting 4x8 sheets delivered ? Commerical truck ?

Thanks for all the help so far, I'm learning a lot

[H2Onut]

I used 1408 glass on both sides, YES NEED backing plate or plywood, that is the one fallback of Kleg is compression. I am lucky, fiberglass supplier 3 miles away. I layed a 8oz cloth on down side and the 1408 on top with 3:1 resin, It is strong. I used 1/2 inch kleg, but should have used 3/4. You can either but it scored, or plain sheet.


www.fgci.com

Mike

[Techno]

Mine was delivered in a 2'x4' box. A whole lot. I ordered 1/2", 3/8" and 1/4"
The size doesn't matter since your covering it with glass it becomes a whole sheet again. Its only foam so its only a core that seperates the 2 skins. No structural strength of its own.
I was told 1/2" is fine for floors and seats. I used the 3/8" on the seats. If you went to a 3/4" then it would be - Hmm I think twice as strong as 1/2". 4 times as 3/8" though.
Laminating a whole sheet would be a major pain, reaching 2' from a side. Doing the smaller panels is nice and easy.


Thanks Tony, I tried to make it interesting. Pictures!
Once I get my mill fixed, the draw bar broke, I'll get the steering column bezel up. I figured out the whole thing. Simplified it.
Its too big and heavy for my lathe.

Mmmmm - Aluminum!