# Plywood Floor in 18' Raft



## natepelton (Feb 24, 2011)

Bought a 4x8 sheet of marine plywood to use for decking, etc, but now thinking of just dropping the whole sheet in as one big floor. Besides weight does anyone know of any problems I might encounter on our upcoming 22-day trip?

Planning to cut 1" circles under every cross bar to hang with straps.

Thanks-


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## stuntsheriff (Jun 3, 2009)

router all edges and cuts


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## 86304 (Apr 15, 2008)

not really a problem/ more of a suggestion. 

fill any whole/gaps with 5 minute epoxy.
use oil base primer
use polyurethane porch paint 
give it weeks to dry.

just the voice of experience. (which usually comes from bad judgement, in my case!)

bob


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## kengore (May 29, 2008)

I started with a single piece floor in my of 15' self bailer. I later cut the floor into 2 sections for a number of reasons.

PRO
It was much easier to tranport the smaller sections, and I could thread the floor in thru the frame sections. 

CON
As a one piece the floor had to go into the tubes before the frame.
More pieces = more exposed edges, more chances to soak up water


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## tmyers (Jun 19, 2006)

Put a band of hardwood on edges of the plywood.


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## 86304 (Apr 15, 2008)

tmyers said:


> Put a band of hardwood on edges of the plywood.


that's one way. (and a great one)

you could try the epoxy on the outside edges and the inside of 1" holes for your webbing supports, also.


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## tahoepa (Jun 27, 2005)

For what it's worth I used a 1 1/2" bit to make my holes. A cam buckle would fit through which was nice.


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## formerflatlander (Aug 8, 2013)

Instead of primer and paint, try an exterior solid color stain (2 coats). Should last longer. And band the edges with old garden hose.


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## Wadeinthewater (Mar 22, 2009)

*Plywood floor edging*



tmyers said:


> Put a band of hardwood on edges of the plywood.


I laced foam pipe insulation along the edge of the floor so that it would not mess with the tubes.


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## 86304 (Apr 15, 2008)

formerflatlander said:


> Instead of primer and paint, try an exterior solid color stain (2 coats). Should last longer.
> 
> Should, but, respectfully, experience has taught me that the oil base primer/poly porch paint holds up much longer and better. being that it's wet and/or under water most of the time.


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## natepelton (Feb 24, 2011)

*Floor Plan*

I was going to coat the sheet with spar varnish after I heavily sand the edges and holes. I was going to mix some sand in for the cockpit area. How long should I allow for that to dry? Does marine plywood need to be sealed?
Thanks-
-Nate


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## 86304 (Apr 15, 2008)

natepelton said:


> I Does marine plywood need to be sealed?
> Thanks-
> -Nate


i'm sure someone here is an expert about the actual atomic makeup of marine plywood but my experience with it is: 
it's still plywood. 
7 ply instead of 5 ply, better exterior surface, maybe better glue, fewer and smaller voids but,
it is still wood.

i hope that give's you some perspective. i wanted it to be some magic material, myself, but it's just wood.


bob

bob


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## 86304 (Apr 15, 2008)

woah, 

too much talk about wood in am!


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## formerflatlander (Aug 8, 2013)

Prob with spar urethane is when water gets under it, it still peels. H&C makes an additive called SharkGrip that can be put in any material for grip. I use it on steps for grip, both interior and exterior. Whatever you use, get good materials.


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## Wavetrain024 (Jul 10, 2011)

Spar varnish is the way to go. Sand the plywood before the first coat, let dry for as long as you can (at least over night) sand the varnish with a fine 150 grit sand paper and repeat as many times as you can. The nice part is if it scuffs you can just sand it and put on a few more coats. Make sure you leave a hole in the floor for your valve!


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## kengore (May 29, 2008)

Patio paint will hold up much longer than spar. Look at the can, you will see that spar is not rcommended for below water line. The alkiline patio paint is formulated for exterior wood and concrete patios. 

In my experiance, spar needs 6 or more coats to seal and needed to be touched up every season. The patio paint took two coats and has lasted for over three years with out any maintainance.

The 'marine grade' in the plywood just means....

1) void free, the knots blemishes are punched out and filled in both the outer and inner layers. (look for the little 'footballs in the plys)
2) a water resistanst glue was used. 
3) number of plys varies with thickness and manufactor, 7 ply is stiffer than 5 ply.

The plywood must be sealed, especially the end grain that shows up in the edges. The pores in the wood act like little straws and suck water deep into the plys. Epoxy can be used to seal the edges and holes, the slow set stuff soaks in deeper. A hair dryer will help to thin it out.

I prefer a slot over a hole, less material removed. Just make sure you leave at least 1.5 X the hole diameter at the edges for strength ( ie. a 1" hole needs to be at least 1 1/2" from the edge. Cut your hole or slots big enough to pass the buckle, not just the web.

Poorly sealed plywood will start to delaminate in a 7 day trip, based on my foolish efforts. If you are going to float for 22 days you need to seal it up good!


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## Stiff N' Wett (Feb 18, 2010)

I wouldn't over think it too much I use oil based min wax from ace but I do sand and restain it every winter. Gives me something to do in the winter and takes about 30 minutes. Your cock pit floor is going get the most wear and tear. My beaver tail and front hatch boards last for ever because they are always covered. I cut my holes so the buckle cant go through then you arent losing straps down in unrechable areas. I've wondered how one big board would work let me know what you end up doing.


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## Willc (May 1, 2013)

Try Restore for decks and patios. One gallon does 50 ft sq. already sanded and waterproof.


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## MT4Runner (Apr 6, 2012)

If you use epoxy, thin with 10% acetone and it will saturate deeper. It does weaken it, so this isn't recommended for a structural application, but we're using if for its sealing properties here.

You can also warm it in the microwave to thin it, but remember this decreases its pot life and accelerates cure time. Do this only with medium cure epoxies or slower--or use the hair dryer after application!!

Epoxy thickened with silica fume would add a lot of abrasion resistance inside holes and around the edges. Saturate first with unthickened, then coat with a 'peanut butter' consistency mix.


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## dogalot (Jul 6, 2005)

Was thinking of trying this to coat my new decks:

Grizzly Grip

I think someone on this forum mentioned it. Anyone have experience?


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## JustinJam (Mar 18, 2009)

*edge attachment*

I love the idea of foam or an old garden hose around the edge. What do you use to attach it? Thinking the same thing for a 16 day trip.


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## Wadeinthewater (Mar 22, 2009)

JustinJam said:


> I love the idea of foam or an old garden hose around the edge. What do you use to attach it?


I drilled holes through the plywood and laced the foam pipe insulation to hold it in place.


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## mrkyak (Jul 11, 2005)

I've had a marine plywood floor for years. 3/4 inch, outside edge is rounded with router, 1 1/2 inch strap holes are rounded with router. I used a marine grade spar varnish, dilute first coat 25% with thinner., apply 3-4coats. The floor is narrow enough so when it hangs with weight it rarely has the opportunity to hit the interior tubes. I think your foam wrapping will not last and become a never ending source of trash you'll have to deal with as it unravels. No need for the floor to be too wide, I contact cemented a piece of durable rubber pad on the floor where the cock pit area is or you can screw on a small piece of diamond plate aluminum. While your at it how about making some running boards for the top rails. Better to walk on and a good base for rigging smaller items.


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