Adding Foam

[Fishin4Life]

I would like to add floatation foam to my boat. It currently has just standard balast tanks with nothing in them. I just think it would be a little safer to have some sort of foam in them. Where would I go about getting this foam? Is it very expensive?

[Valv]

Menards, buy the insulating foam cans, the red label with yellow cap is the most expanding. $ 5.00 each

[RobertELee]

Hey Valv, if I remember right that stuff in the cans is not good for use in boats because it actually soaks up water and will not dry out. there is stuff out there that is good for flotation but I don't know where to get it, probably Boat US or someplace like that. You can correct me if I'm wrong though.

[Valv]

The stuff in cans is closed cells, so it won't soak up water, you can get some marine foam at some retailers.

[Steve Bakken]

Closed cell is the key factor to look for. When we replace a floor in an old boat and take the foam out that's standard open cell foam, it weighs about 100 pounds and is soaking wet. It will say on the can if it is closed cell or not.

[RobertELee]

You both proved me wrong. Thanks for clarifying, I will try to remember that if I ever remodel a boat again.

[hovermn]

The pink or blue foam board, also known as EPS or Expanded PolyStyrene that you'd find at Menards/Homedepot will work great for your aplication. STAY AWAY FROM ANY SPRAY FOAM!!!!!!!!!

Great stuff and 2 part expanding urethane foam WILL soak up water! I've seen it, experienced it, and know lots of people that have used it.

I've been building Hovercraf for years and have used great stuff for bonding foam together and filling voids. In every situation, the foam has acted like a sponge and ended up completely saturated. There are no reasonable ways to dry the foam onces soaked and it will have to be replaced. If the foam is contacting wood surfaces, even those coated in resin and glass, the wood will eventually rot from moisture contact. Epoxy and especially Polyester, which most of the boats you buy is built with, is not water proof.

Part 2 of the horrors of Marine applications of Great stuff is that it keeps expanding long after the initial cure. This can do lots of interesting things depending on where you put it. You could end up with warped or broken compartments. Great stuff is a moisture cure foam. After the initial cure, there will be some foam that hasn't gotten the moisture needed to fully expand. As it gets that moisture, even from humidity, it will fulfill what it set out to do. You will not see me with a can of greatstuff near a boat again.

2 part Urethane foam seems to be the best solution. You can fill any size and shape void or bulkhead simply by puring in the foam. The down side is, you could end up with a boat that weighs hundreds of pounds more and no more floatation then you started with. Urethane foam is slightly better at resisting saturation, but eventually, it too will soak up water. Everything I said about bondind great stuff to wood members holds true with the 2 part foams.

Now, there are things that you can do to help prevent soaked foam if you'd rather not use the pink stuff. I still use 2 part foam in limited applications, but I'm careful how it's used. First thing's first. NEVER pure it directly onto the floor of the boat, especially in the bilge area. That's asking for trubble! If you keep the foam up off the hull in areas that will not see standing water (please don't apply this to Great stuff, just don't use it) you can sucessfully use 2 part foam for floatation. If you make forms from wood, coat them with epoxy resin, pure the foam in, but leave a space between the top of the form and foam. This will be end up being the bottom. Attach that to the top of bulkheads or where ever it'll end up going. The main goal here is to place the foam where it will not come into contact with standing water.

I'm sure there's more that I've forgotten to add, but that's the gist of it. One thing that I forgot to mention is that just because it says close cell, doesn't mean that you're okay. I've seen closed cell perform much like Open celled foam.