Sealing/Waterproofing Ply Wood

Steve-Bream-Fishing · #1 05-11-2009, 09:07 PM

G'day Breamers,

The paint job is almost complete on my tinny (I will post pic once its all done

)

The casting deck and floor will be made up soon, my question is, before I apply the carpet to the ply what is best to use to seal up and waterproof the ply wood?

Cheers

Mandurah Marine · #2 06-11-2009, 01:08 AM

You could fibreglass it but that would add weight. I reccomend a 2 pack sealer with low viscosity - this equates to penetration. Then a topcoat of your colour choice.
Hempel Marine have a product called sealer 599 for the wood. I used it on the deck of my boat which is permanently in the water the deck was consistantly subject to fresh and salt water submersion and over 2 years of pure torture the only rot was in moving areas where the fasteners were drilled (I had a lot of flex - plenty of cracks in the hull of a flat bottom punt I drive at full noise in the open ocean). ie I was extremely impressed with how well it sealed.

crusty · #3 06-11-2009, 02:07 AM

I just used a marine undercoat/primer, and haven't had any issues with rot or water penetration. Glued the carpet down with contact adhesive which adds another layer of protection I guess.

breno1967 · #4 06-11-2009, 02:58 AM

I used Bondcrete to seal the ply decking under the carpet on my old tinnie. Worked a treat.
Breno

Fishigan · #5 06-11-2009, 03:02 AM

Did you use marine ply? Give it a coat of marine undercoatand make sureto put plenty on the cut ends.

BREAM MACHINE · #6 06-11-2009, 05:29 AM

I used PVA glue watered down 4:1 (if I remember correctly) paint on with a heavy first coat & then recoat a couple of hours later as stated before put heaps into the cut ends.

Ozzy1 · #7 06-11-2009, 06:08 AM

I used a good quality oil based paint , 2 coats and extreme amounts on all edges and drilled holes. I then glued the carpet with a waterproof glue

Ozzy

Pisces · #8 06-11-2009, 07:42 AM

i have used the form ply 9mm or 18mm the black coloured one in 2 of mi last jobs of boat building the floor and hatches... if u use this sort of ply u dont need to use anything else to undercoat it .. carpet u can use the contact adesive ... the ply in this sitiation is about 120 bucs a sheet 1200/2400 and is coming in to grades .. one australian made or u can buy from bunnings made in china wich is 60 bucs a sheet at same size.. from joinery shops/cabinet making u can get the contact adesive at 55 bucs per 5 litlers.. usualy i need about 7 litres for 4 mtr boat .. is working a treat and u dont have to ad anymore weight to it as is not needet .. the extra money u should spend is on good stainless steel hinges and screws. dont cut short cuts on galv screws or anything else as u will pull them out in few trips on salt water.. good luck .. if anything else i could help with il b here ..

mattaipan · #9 11-01-2010, 05:52 AM

I have the solution to job at hand, I have used this stuff on a boat I built myself and now using it to replace a few part inside my fibreglass boat (interior is built in ply and glassed over, some of it was pretty shabby)

Its called Wattyl Timber Preserver, its two part epoxy based coating, its very thin, I used it on the built boat, first coat thinned down 50/50, 2nd coat 75/25 then 3rd coat full strength. It soaks it to the glue line on the ply and goes deep into the exposed cut edges.

It not only seals the ply but it also stiffens and strengthens it as well.

You could buy stuff called Epidure made by International Paints, but its pretty much the same stuff, and twice the price.

I have worked with boatbuilders (timber) and built two boats myself, and I would by this stuff again without hestitation.

The boat was painted with Dulux Luxepoxy 4 White Primer and Dulux Luxathane 2 pac, after treated with the timber preserver.

Cheers Matt

Steve-Bream-Fishing · #10 17-01-2010, 04:41 AM

Quote:

Originally Posted by mattaipan

I have the solution to job at hand, I have used this stuff on a boat I built myself and now using it to replace a few part inside my fibreglass boat (interior is built in ply and glassed over, some of it was pretty shabby)

Its called Wattyl Timber Preserver, its two part epoxy based coating, its very thin, I used it on the built boat, first coat thinned down 50/50, 2nd coat 75/25 then 3rd coat full strength. It soaks it to the glue line on the ply and goes deep into the exposed cut edges.

It not only seals the ply but it also stiffens and strengthens it as well.

You could buy stuff called Epidure made by International Paints, but its pretty much the same stuff, and twice the price.

I have worked with boatbuilders (timber) and built two boats myself, and I would by this stuff again without hestitation.

The boat was painted with Dulux Luxepoxy 4 White Primer and Dulux Luxathane 2 pac, after treated with the timber preserver.

Cheers Matt

Thanks for that Matt, what did you use as a thinner?

Cheers

Steve-Bream-Fishing · #11 19-01-2010, 06:38 AM

What about this stuff?

Weathergard Marine Varnish

A high gloss timber finish specially developed to protect exterior marine timber from the harsh elements.

* Provides powerful UV absorption for longer lasting protection from salt water spray, wind and UV DohDohDohDoh.
* Protects timber from darkening and discoloration

will the glue for the carpet then stick?

Cheers

bream miagi · #12 19-01-2010, 10:25 AM

simple easy fix......coat in resin...also use the resin to fuse your carpet to the ply as well....

mattaipan · #13 19-01-2010, 06:29 PM

I would have to look when I get home for the correct thinner, I can't remember the code, but it is a certain epoxy thinner, its great for cleaning out brushes, drips and hands (although you should wear gloves, but sometimes you let that slip) it also cleans up another epoxies like West System.

If you thin down resin, you break it down to much to get it thin enough to soak in as far as the Timber Preserver, because epoxy resin already has a fair percentage of thinning to get it to the state its in, when you buy it.

You would also have to send epoxy resin after coating the plywood to remove whats called Amine blush, although some epoxies end up with very little blush, some end up with quite a bit.

Marine Varnish is mainly used as a clear coating to protect against UV, you could resin a piece of plywood but it won't be protect from UV. Same goes with the Timber Preserver, it also needs protection if your after a clear coating.

The Preserver is almost like water when it comes out of the tin, it soaks right into the first glue line, the ply just sucks it up, which makes it so effective.

Steve-Bream-Fishing · #14 19-01-2010, 08:27 PM

Quote:

Originally Posted by mattaipan

I would have to look when I get home for the correct thinner, I can't remember the code, but it is a certain epoxy thinner, its great for cleaning out brushes, drips and hands (although you should wear gloves, but sometimes you let that slip) it also cleans up another epoxies like West System.

If you thin down resin, you break it down to much to get it thin enough to soak in as far as the Timber Preserver, because epoxy resin already has a fair percentage of thinning to get it to the state its in, when you buy it.

You would also have to send epoxy resin after coating the plywood to remove whats called Amine blush, although some epoxies end up with very little blush, some end up with quite a bit.

Marine Varnish is mainly used as a clear coating to protect against UV, you could resin a piece of plywood but it won't be protect from UV. Same goes with the Timber Preserver, it also needs protection if your after a clear coating.

The Preserver is almost like water when it comes out of the tin, it soaks right into the first glue line, the ply just sucks it up, which makes it so effective.

Thanks Matt, good run down