"surfboard foam" as a core material.

[mogfisher]

Hello. I have a fair amount of 2" thick surfboard foam. I was thinking of using it as a core for some things on my 20' Seacraft CC project. I was going to use it to add 2" to the top of the stringers to raise the deck, and to make some lateral stringers as well. Is this a good thing to use for this? It's fairly hard and dense and seems like a good core to me. I do not know what it is made of, just that it is called surfboard foam. Thanks!

 

[Bondo]

Re: "surfboard foam" as a core material.

Hello. I have a fair amount of 2" thick surfboard foam. I was thinking of using it as a core for some things on my 20' Seacraft CC project. I was going to use it to add 2" to the top of the stringers to raise the deck, and to make some lateral stringers as well. Is this a good thing to use for this? It's fairly hard and dense and seems like a good core to me. I do not know what it is made of, just that it is called surfboard foam. Thanks!

Ayuh,.... I wouldn't,.... Wood will hold a fastener, foam, Won't....

 

[Georgesalmon]

Re: "surfboard foam" as a core material.

I'm guessing thats polyurethane. Bondo is right, won't hold a screw. If you can use longer screws to reach the stringers that will work, but you must replace the foam where the screw is with something denser so you don't crush the foam. I put a new floor in my 17' AL boat made out of vacuum bagged 1/2" polyurethane foam to reduce weight but everywhere there were fasteners needed I put small pieces of pressure treated plywood. (Everything was encapulated in resin and glass so I don't need to hear from everyone about coorosion issues with PT and aluminum.) Cut the deck weight by about a half and got better performance.

 

[mogfisher]

Re: "surfboard foam" as a core material.

It's probably polyeurethane. I was contemplating two options to do this. Use strips of marine ply laminated to acheive my 2" raise or use the foam. Either one would get a few layers of 1708 wrapped over it down to the stringers. The stringers themselves are foam filled fiberglass so in my eyes it would be the same as factory. However, I do see the wisdom in using the ply strips as I would have a good substrate to screw my deck to before it gets glassed over. Using the foam, I dont see that i'd be losing any "screwability" since the original foam stringers are of the same construction, but I also wouldnt be gaining like I would with the ply. I was just thinking for weight and ease of use the foam might be nice. This is a 1970 potter built Seacraft hull.