Lowest Cost, Acceptable Foam For Core?

[CatBuilder]

I have enough Core Cell to do my hulls. I need to buy some more foam right away for my decks.

Deck foam has different requirements than hull foam. An ideal deck foam would have:

1) High resistance to compression loads
2) Impermeable to water (close celled)
3) Good bonding characteristics
4) A low price

So what is the cheapest, acceptable foam on the market? I need some for my deck. I need 1" thick, 5lb or 6lb per cubic foot (M500 and M600 foam, 25mm thick).

The cheap foam I'm looking for only needs to meet #2, #3 and #4 above. I'll be taking it out and putting something more solid in where I have hardware going.

I need to order this now, so I have it on hand when it's time to laminate the deck. Ideas for cheapest deck foam?

[jim lee]

Ive used corecell & Airex The Airex was cheaper than the corecell. But, when infused, the Airex parts used 30% more resin than the corecell ones. So was that cheaper? It sure made for heavier parts. I'd think for a deck, weight would be an issue?

-jim lee

[Alik]

Try PP honecombs for decks - we use them a lot. Much cheaper and compression strength is higher compared with foam.

[rberrey]

You can see what coosa composites has but if you use foam it will have to be one of the major ones to keep a quility build. You might look at a thinner foam, add stringers and or 1/4" ply on top. If it will have no structural affect on the boat it might be an option. Some kevlar on top should take care of puntures.

[CatBuilder]

Ok, thanks, everyone.

Very good point about which ones soak up more resin, too. I guess I'm basically stuck with Divinycell. Of course, I was looking for the "magic" cheap foam that was good for decks but didn't cost much. Probably no such thing.

[War Whoop]

Originally Posted by jim lee

Ive used corecell & Airex The Airex was cheaper than the corecell. But, when infused, the Airex parts used 30% more resin than the corecell ones. So was that cheaper? It sure made for heavier parts. I'd think for a deck, weight would be an issue?

-jim lee

Which Airex did you use??

[War Whoop]

Originally Posted by CatBuilder

Ok, thanks, everyone.

Very good point about which ones soak up more resin, too. I guess I'm basically stuck with Divinycell. Of course, I was looking for the "magic" cheap foam that was good for decks but didn't cost much. Probably no such thing.

I never had a problem with Airex R63.80 soaking up resin in @ 30 years as it is closed cell, I only used sheet foam and have Built very LIGHT with it..

[War Whoop]

Check with the Nida core People ,they like give that stuff away,I would not use it but in a sail boat deck who knows,they also have a foam and are located in St Lucie Fl

[CatBuilder]

Originally Posted by War Whoop

Check with the Nida core People ,they like give that stuff away,I would not use it but in a sail boat deck who knows?

Nida Core... I didn't even know those guys had foam. I thought it was all honeycomb and balsa.

That's where I got my balsa from. I just checked out the website and saw they have all kinds of foam. Good call. Maybe they'll be reasonably priced.

[CatBuilder]

Ahh... the NidaCore foam is polyurethane. No good on hull/decks due to friability.

I'll take a look at finding Airex.

[rberrey]

I didn't check out any of the aircraft foams maybe worth a look. last a foam fr6700 is one.

[War Whoop]

Originally Posted by CatBuilder

Ahh... the NidaCore foam is polyurethane. No good on hull/decks due to friability.

I'll take a look at finding Airex.

No that would be PU this is PET, polyethylene terephthalate.

[CatBuilder]

Originally Posted by War Whoop

No that would be PU this is PET, polyethylene terephthalate.

They have both. PET is ok? I didn't think it was. I'll check again. Thanks.

[CatBuilder]

Who would have thought?

I took out a sheet of balsa today from my materials storage pile and trial fit it on the form. I put it on a place that has a much tighter curve than the deck camber and it worked just fine!

The trick was to use the sheet differently than most:

Instead of putting the open faced side with all the little blocks down into the female form with scrim side up, you just flip it over!

You put the scrim into the female form/mold and press it down, leaving the loose blocks facing you. You can secure it from behind using screws just like the foam.

So... when the half hull comes out of the female form/mold, it will have scrim on the *outside* awaiting lamination and a fully bonded balsa on the inside. One big bonus to doing balsa this way is that you don't have so much filler in the cut between the balsa blocks. Each individual block is pressed together under strong pressure from pushing the sheet down into the female form with the scrim facing away from you. This keeps the balsa blocks very tightly packed and there is no space between them.

A little bog on the outside to fair and smooth, while filling in the micro-gaps between the balsa blocks and then you can laminate right onto that bog. Should work very well.

Do you guys usually tear the scrim off before laminating the second side of the balsa?

[War Whoop]

Originally Posted by CatBuilder

Who would have thought?

I took out a sheet of balsa today from my materials storage pile and trial fit it on the form. I put it on a place that has a much tighter curve than the deck camber and it worked just fine!

The trick was to use the sheet differently than most:

Instead of putting the open faced side with all the little blocks down into the female form with scrim side up, you just flip it over!

You put the scrim into the female form/mold and press it down, leaving the loose blocks facing you. You can secure it from behind using screws just like the foam.

So... when the half hull comes out of the female form/mold, it will have scrim on the *outside* awaiting lamination and a fully bonded balsa on the inside. One big bonus to doing balsa this way is that you don't have so much filler in the cut between the balsa blocks. Each individual block is pressed together under strong pressure from pushing the sheet down into the female form with the scrim facing away from you. This keeps the balsa blocks very tightly packed and there is no space between them.

A little bog on the outside to fair and smooth, while filling in the micro-gaps between the balsa blocks and then you can laminate right onto that bog. Should work very well.

Do you guys usually tear the scrim off before laminating the second side of the balsa?

removing the scrim is a good idea.