Expandable foam tips & tricks

Does anyone have a good idea for foam under the floor when doing a build? I bought some of that "Great Stuff", but is there something better?

Some guys go to the dollar store and buy pool noodles. I know it sounds ridiculous but wait until you price closed cell marine foam.. Its expensive!

Here is a link discussing great stuff as flotation foam.
https://www.boatdesign.net/forums/boat-design/i-thinking-using-great-stuff-20468.html

I used some in my build. I sprayed it under my floor on the sides.

I used the Great Stuff high expansion. I didn't do it for the flotation, I needed to add some support under the sides of my floor. It worked great for that.

Read the directions on the can.

Great Stuff isn't weatherproof and needs to be painted to keep it from absorbing water, it'll suck it up like a sponge in the unpainted mode...but a couple coats of rattle can enamel and you're good to go.

This site is the best site I've found for stuff like urethane foam and epoxy resins:
https://www.uscomposites.com/foam.html

Great prices and service!

When you add up the price by cubic foot of foam between the great stuff and the USC site, USC beats them hands down and the foam doesn't have to be painted.

Something to consider when working with expanding foam:
https://www.youtube.com/watch?v=zAIY0I5GGw4

I knew the "Great Stuff" wasn't closed cell foam, and I knew it absorbed water, but I planned on wrapping it in heavy duty plastic (drop cloth) and then duct-taping the seams to hell and back for underneath the new deck in the front of my boat. It normally wouldn't get wet because it's under the bow cap and the V up front is higher than the bottom of the boat by design. It wouldn't get wet unless I get swamped.

My mods didn't add much weight to the boat and all the original foam is still intact. I'm thinking that I can get away with my idea of just wrapping it and sealing it.

I'm maybe talking about 2 cubic feet of foam total.

What do you guys think?

Don't you want to use the rigid foam insulation from Home Depot, etc? I used it under my floor, between the ribs.

jigngrub said:

Something to consider when working with expanding foam:
https://www.youtube.com/watch?v=zAIY0I5GGw4

Click to expand...

Thats a funny video, thanks for the link
Tim

Andy Taylor said:

Don't you want to use the rigid foam insulation from Home Depot, etc? I used it under my floor, between the ribs.

Click to expand...

I was thinking of avoiding the cutting and piecing together. It's really just a touch of foam to take up the very front of the bow that I wouldn't be able to reach or use for storage.