Decking a boat and water run off

[Dennis1958]

I'm getting ready to deck my aluminum boat in the next two weeks. I will be using marine grade plywood and had a couple questions. Should I seal the plywood with a paint ..if yes.... what kind and where can i purchase it and finally..... I was going to try and fit the deck tight to the side of the boat. Im leaving that aluminum but then I was thinking... should I leave a space for the water to drain? Any suggestions are a heads up before I get started. I have the plywood , carpet and glue..so no turning back now .

 

[sdunt]

Re: Decking a boat and water run off

ANY wood will rot if not protected with paint, epoxy, etc. Get some A/C exterior plywood, you will most likely find that the A/C plywood in the yard is made with Exterior glue eventhough its not sold as exterior.

The best way to protect the wood is to seal the entire floor, top, bottom edges, etc with epoxy that way water will not get in. You also need to seal all of the mounting holes and any seat mounts, etc. You will need to cover the epoxy with paint or varnish or come thing. Epoxy is not UV stable and will yellow and degrade over time if not protected. As for water run off thats up to you.

In fiberglass boats the floors are sealed to the hull and the water is expected to drain to the rear and into the bilge.

Be VERY careful of using the new AC2 treated plywood in an aluminum boat. The chemicals in AC2 will eat all metals except stainless and hot dipped galvinized.

 

[andy6374]

Re: Decking a boat and water run off

With marine grade fir (AB) you'll be fine with the aluminum. You should seal the wood with at least a couple of coats of epoxy, I'd put a layer or 2 of glass myself.

Don't fit the deck too tight with the hullsides as that will create a hardspot. I am not familiar with aluminum boat construction but I think hardspots would still be an issue as it is with fiberglass boats.

 

[Chris1956]

Re: Decking a boat and water run off

Dennis, You will need to seal all surfaces of the plywood. I will assume you plan a flat deck for fishing. Don't forget to build some 2X4 supports under the deck, and along the gunwales, to make it strong. For a boat, you should use SS or brass screws and bolts, and build it a lot stronger than the equivalent structure you would use for a house!

 

[Dennis1958]

Re: Decking a boat and water run off

What is the difference between epoxy and exterior paint?
Where can I buy epoxy? Sorry.. I've not familiar with epoxy.

 

[Kevin70]

Re: Decking a boat and water run off

Being critically un-rich, I'm the guy who always chimes in with the cheap way out. My brother-in-law used treated plywood and carpet in his jon boat, and it has held up great for the past 5 years. However, coating everything with epoxy or polyester resin with make it last 4 time as long. [colour=red]This is polyester resin.[/colour]

 

[sdunt]

Re: Decking a boat and water run off

Its all on that scale of how much do you want to spend vs how much you get out of it.

Epoxy is absolutely the best at sealing wood so it is water proof. Polyester resin is probaly the next best and paints come in somewhere after that.

It is curious that the pressure treated plywood in your brothers boat has stood up for 5 years. Keep in mind that pressure treating is there it kill bugs and mold. It is NOT waterproofing.. Thats why homeowners are constantly putting Thomson's water seal on their pressure treated lumber decks. and you can see what happens to pressure treated wood that is UNPROTECTED. It of course doesn't rot, it splits and checks and turns to splinters from the swelling and shinking caused by the water.

So it depends on how much $$ you want to spend. Polyester is economical, used on millions of Fiberglass boats. But for it to stick to the wood for the long haul you need to use some kind or reinforcement, veil matting or light weight cloth.


Poly by itself will come off

 

[svdk]

Re: Decking a boat and water run off

My dad and I put a deck on our aluminum boat about 18 years ago. We used a welded aluminum frame bolted to the boat with stainless hardware. The deck (marine grade ply) was the bolted to the frame. If I remember correctly, we put a coat of thinned epoxy on the plywood.

The deck has held up great. The carpet on the other hand has seen better days. The wood was not tight against sides of the boat, maybe a 1/2 in. to 3/4 in. away from the sides, this allowed water to dry out of the storage area below and allowed the carpet to be tucked in around the edge of the deck.

The boat was also kept covered or in the garage when not used, which may explain the condition of the plywood.

 

[Dennis1958]

Re: Decking a boat and water run off

Lowe's hardware store has an epoxy paint for garage floors. It says it's interior or exterior. Do you think that would work? It looks like it would.

 

[andy6374]

Re: Decking a boat and water run off

If you are not planning on laying some glass....I would encapsulate it will a copule of coats of epoxy resin.

 

[seven up]

Re: Decking a boat and water run off

hey i've used the porch paint on 12" interior pine shelving used on the top of a fence for a shelf. the pine was wiped down with boiled linseed oil first. the porch paint is alklyd enamel. so far so good after 5 years.

i really jumped on "svdk's" aluminum frame technique...great reinforcement.

sealing the end grain of your plywood and framing is important and i've read many perplexed inquiries about pressure treated on boats: seperation, buckling, some real disasters that make it sound like a waste of time. the regular exterior plywood appears to give better performance, sanded, sealed, painted.

if you use paint, do both sides and all the end grain and leave room for drainage...that's my 4 cents worth