Sandwich Superstructure

[fencer]

Hi everyone,

I am working on a project where I m designing a superstructure in composite material, for a 90m long ship. the superstructure itself is 70m long. Any ideas on what kind of material would be good for this. It is a passenger ferry so fire options are very important.

Thanks
Fencer

[yokebutt]

Fencer,

Since you're in Stockholm, I think you should contact DIAB, they are the makers of divinycell foam cores, and they carry a line of balsa core, and best of all, it's a Swedish company.

They really pioneered construction of light-weight composite ships together with the Swedish navy. The contact info I have is a bit old, but give it a try anyway, Repslagaregatan, Box 201, 312 01 Laholm, Telefon 0430-12800.

Lycka till!
Jocke.

[yokebutt]

Another good source would be KTH:s department for lightweight structures, if they can't help you, nobody can.

Yoke.

[marshmat]

"fire options are very important" doesn't usually mesh too well with "composite". Carbon/epoxy would be a good one; pricey, though. Perhaps vinylester/polyester with aramid or fibreglass. Fire retardants in the resins of course. But I think you'd be better off, for cost, fireproofing and ease of construction to go with aluminum. The weight would probably be similar. Unless you intend to build a few dozen of these boats, the tooling for composite probably wouldn't pay off as well as an aluminum superstructure would.

[yokebutt]

Marshmat,

Surprisingly, aluminium isn't neccessarily always the best option for fire-proofing because of its high heat conductivity. No simple answers for this question I'm afraid.

Yoke.

[Herman]

Contact Alcan for their T90 foam. Relatively low weight, and good fire properties. (FAR25 !!!). Much better than any PVC foam.

Another option would be PIR foam, but mechanically it is ehhmm, not so good...