Foam

[jorgeinmiami]

I'm at the point in my skiff build that I need to replace the foam under the deck.

So what foam should I use?

And by the way the Seacraft is also also coming along

[JohnC]

US Composites has kits of various sizes and density - they are in West Palm and I believe they will ship it. Merritt sells 2# and maybe some 4# too - they are in Pompano Beach. Both companies have knowledgeable staff that will answer your questions if you call them.

2# for flotation (between stringers under the deck)
4# for structural (with glass over it - like inside Seacraft Box Stringers)

US Composites sells denser foams too but I honestly don't know what it's for.

[jorgeinmiami]

Thanks. so it #2 since it for under deck and between stringers

[cdavisdb]

FYI, poured foam may be listed as closed cell, ie, water doesn't penetrate. Often it ain't so. Mine, used in diving equipment, absorbed lots of water. Later, I bought some planks of closed cell and it really was.

[JohnC]

2# is correct for your application. The stuff from US Composites is closed cell. As cdavisdb said - that's important.

To the best of my knowledge, older variants of "closed cell" a/b mixed foam were prone to water absorption. I have heard stories of BW boats that had problems with gaining water-weight a few decades ago, maybe even more recently. The newer closed cell foam is not prone to this.

Do a small test batch so that you can anticipate how fast and how much it expands - it outgrows the mixing container pretty fast. When you install it, mix it close to your work and work in small batches until you fill your space. Cover anything nearby that you don't want foam on - its messy. Be careful where you set your used mixing containers down!

Good luck

[Bikecop1]

So my boat has no foam in it at all, anywhere. Should I add some or leave it as is.

[gofastsandman]

Originally Posted by Bikecop1

So my boat has no foam in it at all, anywhere. Should I add some or leave it as is.

IF I were to add foam, I would add just a little under the cap.

Not around hoses or rod holders.

[JohnC]

There are wisely reasoned opinions on both sides of the foam or no foam issue. I used to have a Mako that had foam everywhere under the deck. I "sunk" it offshore. By sunk I mean that the bilge (about 24" x 36" of space under the deck) became completely flooded due to a broken livewell drain line. I noticed it because the boat felt heavy and the stern squatted when I put it in gear. There was never any danger of sinking or capsizing. Nothing to worry about - find the leak and fix it and then keep on fishing.
I was also on a 30 Riborunner with no flotation when both bilges failed (a few cut-off pieces of wire ties washed back into the pumps and jammed the impellers). The water in the bilge came from a livewell that was not properly plumbed (again!!). That was downright scary. We rigged the livewell pump to remove water and hurried to safe harbor before things went really bad.
If you have holes in the bottom of your boat (livewell, washdown, transducer, etc.) then the possibility of mass amounts of water getting into the bilge is present. I suppose waves coming over can do the same thing but I have never experienced that.

For me I prefer foam to no foam. There is a downside with regards to access and serviceability but I'll take it because it saved my bacon miles offshore.