Wet Boat Floor Foam

[jbell1981]

Just got a boat last week that needed a little work. The carpet was bad and once I ripped it up I noticed some wet/rotten spots on the floor. So I decided to replace the floor too. Once I got that ripped up I noticed that some of the foam is pretty wet. When I push on it with my finger I, water gets squeezed out. Should I worry about this?

 

 

[my4x4yj]

The foam in a boat is basically a type of the same foam used as insulation, in the boat used as floatation. It is porous and absorbs water, you will need to let it air dry for some time. also make sure that the drain channels in the hull are clear and prop the boat up so that the excess water can drain out. the rotted floor allowed the water through and by the looks of it sat in there for a long time. not drying it will result in mildew and mold, smelling real bad, as well as adding an excessive amount of extra weight to the boat. Areas of foam that look bad or broken down can be repaired  and added to with spray foam from a can, excess can be trimmed flat with a long saw blade or knife.  Make sure that the plywood used to replace the floor with is marine grade, more expensive but designed to stand up to repeated submersions in water. Hope you kept the old floor to use as a template for the new one makes things a lot easier.

[delcecchi]

I would say you need to replace at least all the soggy foam. 

That boat is pretty old, looks like an alumacraft backtroller. 

It might be best to just go ahead and replace all the foam.  You wouldn't want it to sink if it swamps.

[fishnowworknever]

Yeah like I and another said above, get the 2 part foam that you mix together and pour in the spaces.  You get a lot more bang for the buck and it's done correctly using the correct material.

 

The easy way to do it is to put the deck (or floor, although boats don't have a  "floor") in place first, drill out a few 1" holes using a hole saw or hole drill bit...whatever you want to call it...and save the cores/plugs, pour in the foam and let it come out of the 1" holes, then wipe up the excess.  Fill the holes with the 1" cores you kept and seal / glue them place with some 3m 5200.  No trimming with a knife needed and it's filled perfectly.

Edited May 28, 2015 by fishnowworknever

[jbell1981]

Thanks for the input.  It's a mid 80's smoker craft.  Yeah I saved the floor to use as templates. 

So can I just use the expanding insulation foam in the can that is used to seal around windows and doors or is there something else I should use? 

[Rick G]

Easiest way would be to take the old foam up and put down a bunch of the canned spray type foam. Best way would be to contact someone who sprays closed cell foam insulation for a living.  If it were me, I would spray the bottom with canned foam and cut to fit a couple pieces of the hard pink sheet foam  so it lays flat for the floor boards to rest on.

[h8go4s]

I'm a little suspicious of the canned spray foam. Make sure you use closed cell foam, not open cell foam. There are foams specifically for boats. Here are some possibilities:

http://www.jamestowndistributors.com/userportal/show_product.do?pid=2198

http://www.carbonfiberglass.com/Foam-Core/expanding-foam-ab-2-part-pour

http://www.westmarine.com/search?text=foam

Make sure you leave drainage channels and wiring channels. Do this right. If you swamp the boat, you have a chance to survive as long as the boat stays floating. If it sinks, you're in big trouble.

[fishnowworknever]

H8go4s has the right links above.

 

Do not use spray foam from home depot, purchase the 2 part closed cell foam from one of the links listed above or just do a google search and shop around.

[jbell1981]

Thanks for the additional replies and links. I was able to find a closed cell spay at a local hardware store that I am going to try. I am going to replace the areas that seem to be water logged. Once I start cutting out the existing foam I will find out if the entire bottom is water logged and if so, replace the whole thing the with 2 part mix in those links. 

[EBass]

Test the boat for leaks while you have it all ripped up.  It will be easier to replace/repair the rivets if needed. That foam looks nasty/moldy. I would replace it all. Keep the pics coming. I wish I would've taken pic through out the process.  Good luck 

[jbell1981]

I know I should replace it all, but the additional $100-$200 to do that really wasn't in the budget (the plywood and carpet took all that up). So if I can salvage some of it safely I will. 

I will take more pics through the process and post them here. 

[jbell1981]

Well I cut out a few test sections of the foam and the bottom third is completely water logged even in areas where the top looked fine.  So I guess I will be replacing it all.  

Also,  I tried the can of foam I got and it could barely fill a 14x12x4 section. Also,  it is not as dense as the original stuff so I won't be using any more of that. 

[Cliff Wagenbach]

I also had the same wet foam problem with an old Alumacraft that I refinished.

I removed all of the foam and it weighed more then the boat did! I bet that boat would have sunk like a rock if I had left the old foam in  it!

Replace it all with a good 2 part closed cell foam!

Good luck! Lots of work ahead for you.

Cliff

[jbell1981]

Got the old foam out.  Some pieces were very heavy.  Definitely waterlogged.  

[EBass]

Much better! Take your time. It took months for my rebuild. Did you test for leaks? 

[jbell1981]

Well I hope this doesn't take that long. Hoping to have it on the water by the end of the month. 

Haven't looked for leaks yet. Probably with weekend. 

[fishnowworknever]

repost

Edited June 3, 2015 by fishnowworknever