Which Foam for Core?

[Toby P]

I am looking to build a 4.3m (14ft) sailing boat of moderately high performance. It will be sailed mostly on lakes, with the occasional outing on the sea - so fairly low loads. I am thinking of using foam sandwich construction - but which foam should I use? Airex, Corecell, Divinycell or anything else? What are the advantages and disadvantages of each? My priorities are for the boat to be light, long lasting and not overly expensive.

Many thanks.

[antonfourie]

Have a look at this site for more details on foam cores

http://www.netcomposites.com/education.asp?sequence=45

[Toby P]

Thanks Anton, there is some useful stuff there. However, most of the articles seem to be written by SP, hence the slight bias about SAN foams.

I definitely want to go for a SAN foam like Corecell, or a PVC foam but I wondered what the most popular ones at the moment are.

Divinycell, Klegecell, Airex etc all seem to be similar stuff - which is the best?

[antonfourie]

That depends alot on money and what is avilable where you are. I did have some data comparing all of them, but it is not on this PC (work PC), I think that Airex came out best in the money vs strength vs workability

[jimslade]

Check out Nida core. I've had good success using it.

[SailDesign]

For your purposes, Airex will be a pain, since it cannot be sanded easily, and therefore must either conform perfectly to the shape, or be kerfed and thus heavier (resin sits in the slots...)
Corecell or balsa would be the best bet. I know balsa gets a bad rap, sometimes deservedly, but it is still good stuff when used properly (i.e. NEVER, NEVER drill through a balssa-cored laminate - use it where there will be NO HOLES and use foam in the holey areas.)
In the shop, we use Corecell or balsa exclusively for sandwich structure, and Divinycell for anything that is less important.
Steve