Advice on Plywood Flooring

B

bariutt

Member
I have an older Princecraft 16 ft wide and deep boat with a 25 HP tiller outboard. This boat has full seats running across the boat.

I would like to install removable plywood floor panels between the seats. I was thinking of using 3/4 exterior grade fir plywood covered with that vinyl pebbled fabric that you can purchase for exterior decks. You see that fabric on the floors of a lot of factory installed units.

Any advice would be appreciated. Do I build ribs to elevate the floor off of the aluminum bottom? How do I attach the vinyl - do I glue it or staple it with stainless staples.

How do I keep the plywood from soaking up water? Should I use pressure treated plywood instead?
 
Don't use treated (green) plywood to will corrode the aluminum.I would go with marine grade plywood and glue down the vinyl.
 
I second on not using treated lumber. An alternative would be an MDO sign board material available at Menards (that's where I get it.) I've used it with excellent results for that purpose.
 
You might want to check out 3M structural polyurethane foam, glass reinforced board. Boat builders are using it instead of plywood, no rot issues to worry about.
 
I won't use exterior grade plywood , it's really not designed to be subjected to water for long periods of time. The glue won't hold up and the pile will delaminate. The marine grade is a much better design and will hold up the best in the long run. That being said the treated plywood shouldn't be disregarded either they no longer treat the wood with CCA, ACQ, or the real bad guy CBA. The current treatment which is water based (ACZA) has far less copper in the mix they have had in the past and is more aluminum friendly then ever before. I've had it in my aluminum boat going on 4 years now with out any signs of corrosion what so ever. It should last about 10 years if primed and painted properly.


Dean
 
I already have a full sheet of exterior grade fir plywood and some spar varnish.

In that I already have these materials lying around in my shop I might as well use them. I know there are more durable solutions but where I live in Northern Ontario you cannot purchase marine plywood or anything exotic.

I was thinking of thinning the spar varnish down with paint thinner so that it soaks into the plywood and giving the plywood a few coats before I wrap it with the pebbled vinyl fabric. Will varnishing the plywood with spar varnish help or hinder the process?????
 
The issue with plywood floors in aluminum boats is that even if you seal them up nice you put so many holes in them installing and from wear that they get wet from the penetrations anyway. Were it me I'd take one of 2 approaches. Just use exterior plywood and try to get it sealed with someting like an oil based paint or spar and plan on it rotting over time or do something final like a foam composite or aluminum that won't rot. As an aside the exterior plywood will be fine and the glues are the same as marine plywood, just the ply are not as nice and there are lots of voids.
 
DONOT use pressure treated, it is full of salts that will turn aluminum into Swiss cheese in a heartbeat.
I used 3/4 exterior plywood in my smokercraft. Gave it a good coat of primer on both sides, really thick on the edges, and then a coat of grey exterior latex, same paint I used on the hull.
Sure it may rot after 10 years but at $25/sheet, its not a big deal.
I don't have carpet, don't see a need really. It will just hold water between it & the wood.
View attachment SmokercraftLookingAft.jpg


View attachment SmokercraftLookingForward.jpg
 
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