Foam backing of bulkheads

[heartofgold]

What type of foam did you use to back your bulkheads and firring strips; is it styrafoam or is it more like a "foam rubber"? Which bulkheads would require this kind of backing, and which would not?

[radicalcy]

I know you didn't ask me, but for the record, I just did this on my Columbia Sabre (1965) and used the closed cell foam tubes that they use to wrap air conditioning condenser return lines. It comes in packs of 4 or 5, 36 inches long, split down one side. I just cut it into strips about 1/2 an inch wide lengthwise and epoxy it in place. It won't absorb water, and is firm enough to prevent hard spots and doesn't crumble like styrofoam. Really easy to work with. I'm pretty sure you can buy it by the roll if you need more than a few lengths

[Tim]

Doug,

What you use depends on the application, of course. The bulkhead fillets are there to isolate the bulkhead from the hull, and to make tabbing more effective (by spreading the tabbing over a wider area) and easier (by helping to ease the corner between bulkhead and hull). In this application, I feel that any closed cell, relatively dense foam would work fine. You want something that isn't immediately crushable or "cushiony", but it need not be a highly structural foam either, since the foam is not at all relied upon for strength in this application. The fiberglass tabbing ends up providing all the strength, and the foam could effectively be considered to not exist once the entire bulkhead is properly tabbed in and secured.

I used blue styrofoam insulating board for the bulkhead fillets. Certainly it is not a product I would choose for a structural core in any application, but as an isolation material I felt it would work well. You have to consider whether you're using foam more as a "mold" material, or a place-holder, or whether it will have structural signifigance in the finished product (such as a deck core).

An ideal choice might be Airex foam, or similar.

The firring strips for the ceiling in the v-berth are even less structurally significant, and exist only to hold wooden battens into which I will install screws through the ceiling. I also used the blue styrofoam here.