Is this marine ply?

[Bilopete]

I gave the floor of the boat a wash a few weeks ago and have since noticed slight buckling. I thought marine ply was more resistant to water, hence I am starting to question whether this is marine ply.

Can you have a look at the photo and confirm if it is or isn't?

If it is not, can somebody suggest a cheaper alternaltive to marine ply? I hear construction ply is half the price and is just as suitable? Also was thickness should I be considering? 19mm sounds to big and over the top. Would 12mm be sufficient?

I have a aluminium fram under the exisiting floor to support it if that makes any difference?

Cheers

Biloepete

[wiz]

That does not look like marine ply
If that is a tinny floor then it is just normal ply.
Just do a search there is heaps on making floors and how to seal normal ply
Cheers

[Bilopete]

Thanks wiz,
Yes I have searched for floors and there are heaps of posts but nothing I can find relates to costs. Sure normal ply is cheap but by the time you buy sealant is it still cheaper than marine ply?

[dnej]

OK,that looks like form ply.Heavy stuff,great glue quality,but breaks down if the ends are not sealed.

Dont be mistaken about marine ply.

Its not the timber,its the glue.
Marine ply just has a better finish for boat building,but there are many ply wood configurations,that have just a good a glue.

For example common old structural ply from your local hardware,used in house construction.
Comes in a lot of thicknesses,and does agreat job,so long as you reseal the edges with say Lanolin grease,and then paint with an oil base paint.

Dont buy expensive marine ply,unless you want a perfect finish.
David

[Outsider1]

Thanks wiz,
Yes I have searched for floors and there are heaps of posts but nothing I can find relates to costs. Sure normal ply is cheap but by the time you buy sealant is it still cheaper than marine ply?

heaps cheaper even after sealant costs. Use construction ply that is what everyone uses.

Cheers

Dave

[Bilopete]

heaps cheaper even after sealant costs. Use construction ply that is what everyone uses.

Cheers

Dave

Thanks Dave,

So where do you purchase construction ply from?
What thickness should I get?
Does it still need to be sealed?

Cheers

Peter

[Outsider1]

Thanks Dave,

So where do you purchase construction ply from?
What thickness should I get?
Does it still need to be sealed?

Cheers

Peter

So where do you purchase construction ply from? Any good Hardware store should have it, Bunnings has it but I think someone said they tend to be a bit dear.

What thickness should I get? Unless you are a real big guy (125kgs+), then 12mm should plenty strong enough.

Does it still need to be sealed? Yes definitely, any of the Marine Sealers will do the job.

This is the best recent thread I have seen on the subject;

http://www.ausfish.com.au/vforum/showthread.php?t=124243&page=5

Cheers

Dave

[Roughasguts]

The floor on my Signature was fine.................... until I sealed it with marine paint.
On the bottom side of the glued on carpet I lovingly gloss painted the ply, It had a dull grey under coat on it before I painted it obviously so it breathes the mosture out! And now get a slight buckle when I wash the floor off cause the moisture stays in the ply longer I guess. (But I don't get the mouldy look any more)

[BM]

Bilopete,

Structural ply is also known as "case ply" or "CD ply". Don't go to Bunnings as they are a stitch. Look up Plyboard Distributors online or the old fashioned way and visit one of them. As a bonus most plyboard companies have a decent "offcuts" section so you can more often than not buy the piece you require for a fraction of the cost.

For most applications in boats structural/case/cd ply is all you need. These and marine ply all share the same waterproof glue. However......... marine ply is made from different timbers. The marine ply timbers are of much better quality than the other ply types.

Having said that, every boat repairer I know (and I know a few being in the marine trade) uses structural ply for floors and transoms etc

Cheers

[sneddo]

i just recently fitted out my boat with CD grade ply in 15mm thickness. It was sealed with bondcrete straight from the tin, this was recommended by the plywood factory for marine use. It was only $61.50 a sheet and once covered with carpet you cannot tell the difference.

[Donny Boy]

Same deal here. Just did a full reno on my old Crestrida, used 17mm form ply on the floors, but smothered it with Bondcrete on all the edges. Must have put 3-4 coats on it. When secured down, gave it to a fibreglass boat builder to glass the floor and do the transom, and he reckoned it was gunna be AOK.

[Bilopete]

i just recently fitted out my boat with CD grade ply in 15mm thickness. It was sealed with bondcrete straight from the tin, this was recommended by the plywood factory for marine use. It was only $61.50 a sheet and once covered with carpet you cannot tell the difference.

Why bondcrete instead of a marine sealant?

Edit: I see why now after looking up bondcrete on the net. Did you apply it as is or did you dilute it 1:4 (water) as per the directions?

[Outsider1]

Why bondcrete instead of a marine sealant?

Sounds silly Bilopete but Bondcrete works and is miles cheaper than marine sealants. I use Bondcrete for all sorts of repairs and sealing, it is water soluble so you can dilute it for best application rates, but once its dry it forms a waterproof seal.

Cheers

Dave

[Bilopete]

Then bondcrete it is!

I assume you only do the edges of the CD ply and not all the sides?

[Outsider1]

If you aren't convinced about Bondcrete, the manufacturer Bondall makes another similar product called Aquatite that is designed specifically for sealing permanently wet areas.

http://www.bondall.com/DataSheets.htm


Cheers

Dave

[Outsider1]

Yes I would only do the edges. The faces should already be appropriately sealed. If you read back in those previous thread links you will see that you need to let the ply to continue to breathe so it does not retain any moisture.

Cheers

Dave

[Bilopete]

If you aren't convinced about Bondcrete, the manufacturer Bondall makes another similar product called Aquatite that is designed specifically for sealing permanently wet areas.

http://www.bondall.com/DataSheets.htm


Cheers

Dave
Yep after looking at the datasheet I am convinced...i was just confirming that all I needed to do was the cut sides of the cd ply and not ALL sides of the ply.

Cheers

[Bilopete]

Ok ready to go. Got my CD ply (12mm) and a can of bondcrete....sounds like a upcoming week-end job!

Thanks everyone for your help!

[Scott nthQld]

I recently went through the same thing.

I finished putting a new floor in my boat a couple on months ago.

I used CD Ply and sealed it with Bondcrete all over, paying special attention to the edges. Some will say to leave the underside unsealed as the timer needs to dry out after being wet, but if its sealed properly, it's not going to absorb any water is it?

I used 2 2400X1200X12mm sheets (I used off cuts for something else) and a 1ltr tin of bondcrete, this cost me about $120 total. I then bought some new marine carpet and used gel bond to glue about 100mm from the edge top side and about 50-75mm underside and stapled, that set me back another $100.

So for $220 I had a brand new floor that I know was done properly cos I did it myself. Overall it took me about 4 days to complete (most of this was waiting for glue to dry etc), but being lazy, I managed to drag it out a very long time.