Sealing underside of plywood floor..

[VooDoo]

Just removed the carpeting and found several areas that were rotten on the floor. Main floor was replaced 3 years ago with 3/4" marine ply. But they didn't seal it. Between the carpet and the floatation foam, new floor was already deteriorating. Anyone have any ideas as to what I can use to deal the underside of the plywood. I plan to use Raptor Bedliner on the top side but it would be too pricey to use on both sides. Any suggestions?

 

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[VooDoo]

Home Depot sells 4×8 vinyl sheeting. Could I put this down over the flotation foam to rest the plywood on?

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[VooDoo]

I can screw down through the aluminum runners to hold ply and the vinyl. Vinyl is 1/8" thick. Would probably have to drill. Will probably remove about 10" of carpet and run the bed liner up the sides a little ways.

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[VooDoo]

Would garage floor paint or porch paint work to seal the underside and edges of the ply?

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[jth21usa]

Ever think about fiberglass? It’s really pretty easy.

[nhjim]

i would not do the vinyl under creating a water trap. seal bottom with epoxy.

[VooDoo]

I have used fiberglass it's not cheap anymore. What kind of epoxy?

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[SylvanTroller]

West System 105 epoxy and 205 hardener. Seal both sides with this stuff and that wood will outlast us all.


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[SylvanTroller]

You could also use spar varnish as a cheaper solution but it’s not quite as good. Check out the iboats forums. Tons of info on this type of stuff.


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[VooDoo]

Thanks

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[jth21usa]

13 hours ago, VooDoo said:

I have used fiberglass it's not cheap anymore. What kind of epoxy?

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The epoxy is usually much more expensive than the fiberglass cloth

[MCF]

I believe the vinyl would be a moisture trap.  I would paint the underside and have done that successfully with boats in the past.

[Jack]

You can go to Walmart they sell  fiberglass resin in a gallon can in the auto department for about $35.

buy some outdoor plywood cut it to size then roll 2 coats of the resin on and brush the edges real good .

last you 20 years . Done it a bunch , same for transoms .

 

Good Luck !

[shu9265]

I just redid my Islander this summer.

Use West System 105 epoxy and 205 hardener.

 

DO NOT use pressure treated plywood !   It WILL react with the aluminum and make a real mess !

 

If you use the west system, make sure you treat all edges and surfaces with (2) Two coats

 

You won,t be disappointed with the results.

[scobar]

My Lowe has a full aluminum floor, just
A thought

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[sherman brown]

I agree on not using treated wood. just get exterior grade plywood the only difference in it and marine is the marine has less knots and one side is extra smooth. I sealed mine with paint on truck bed lining I bought at Oreillys. but a few coatings of polyurethane should seal the bottom and edges and last for yrs. I sealed all the seams and edges after the floor was installed with cheese cloth and fiberglass resin.

Edited September 29, 2018 by sherman brown

[2lbperch]

I use raka epoxy. Nice guy, cheaper than west system, on the east coast also. Cut the pieces & 2 coats.

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[VooDoo]

I ended up getting Sherwin Williams 2 part epoxy. Great warranty, great price. Around $75 for 2 gal. Got it tinted light gray with non skid additive. Will see how it goes. If its too slick I'll put Merideck vinyl flooring over it. Should seal every thing well. I'll post pics when i get it done.

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[rolmops]

It would be a good thing to find out where the humidity comes from . It may be that your flotation foam is water logged.

 

[VooDoo]

The foam was wet but I've pretty much got it dried out now. Left it open and had a fan on it for 3 days. Took a couple waves over the bow and got caught in a couple monsoon rainstorms. Carpet held the moisture in. Never had a chance to dry out. No more carpet

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[ri rory]

I HAVE REFLOORED  TOO MANY ALUMINUM BOATS.  YOU MAY HAVE ANOTHER ISSUE TO ADDRESS.  BEFORE YOU DO ANYTHING, TAKE A PIECE OF 1'' PVC PIPE AND DO SOME CORE SAMPLES OF YOUR FOAM  IN EACH COMPARTMENT TO MAKE SURE IT IS NOT SATURATED......IF IT IS, GET IT OUT NOW. IT SOUNDS LIKE IT MAY BE AND IT ADDS SO MUCH WEIGHT--SEE I BOATS FORUM ON REBUILDING. I THINK THE SATURATED FOAM KILLED YOUR FLOOR, ESPECIALLY IF ITS MARINE PLY.  IF MARINE PLY CAN DRY, IT LASTS FOREVER.

 

BEFORE I COATED ANYTHING I WOULD BUY SOME 1/4'' THICK ALUMINUM STRIPS TO ADD TO EXISTING ALUM. FRAME AND LIFT THE FLOOR ABOVE THE FOAM FOR DRYING AIR FLOW.  COAT BOTH SIDES WITH 2 COATS OF EPOXY.  YOU WILL NOT BE HAPPY WITH THE BEDLINNER AS IT WILL CRACK OVER TIME WITH FLEX.  IF YOU HAVE DRY FOAM AND ALLOW AIR FLOW JUST USE GOOD MARINE CARPET AS IT DRIES FAST AND IS EASY TO REPLACE.

 

FEEL FREE TO PM IF NEED ANYTHING

 

COACH

[fishmaster13184]

I’d rip all that foam out, they just paint the new wood on all sides and add an aggregate for traction on the top side

Edited October 3, 2018 by fishmaster13184

[Skamaniac]

Home Depot has a waterproofing product in with tile supplies called Red Guard.  You can roll it on or brush it - I use a whizzie roller.  The stuff is awesome and goes on fast and smooth.  Costs about $50 for a gallon.

[Knotlost Charters]

You need to get that foam out it is holding water against the flooring, probably waterlogged as well. Fiberglass, by the way, is water permeable, epoxy is not

.

[VooDoo]

Havent been able to work on the boat due to monsoon weather. I like the idea of putting aluminim strips down for separation of the floor and foam, but 1/4" bar stock in the amount that I need is just too pricey. I'm thinking of taking composite deck boards and ripping them down to strips on a table saw to use as spacers.

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