if you are making a plug. you can use any type of foam. you just have to seal the foam. i have made submarine hulls using pink foam, blue foam, and mono foam. but what i had to do was to first get a good copy of what i needed. then put a cover of white glue. white glue is sandable. but it is not that strong. epoxy is best, but that is expensive. the important thing here it to make sure the entire hull is covered. using a hot wire works. but i dont like the smell. and if you are good with the knife. you dont realy need a hot wire cutter. polyester fibrglass cure with heat. that is why you must put a barrier agianst the foam. but the big thing here is to make sure the entire foe=am plug is cover. or you get hard goop
cougar
long live the cup
Well, after trying everything I could get my hands on I settled on Last-a-Foam (which has a polyurethane component) for the Yankee III hull. I’ve now carved five of them using varying techniques, and it works pretty much like wood.
The dust is a pain, but can be dealt with. Unlike MDF (or many “natural” woods, like ebony) it is chemically neutral and so falls into the category of nuisance dust rather than something that can really hurt you. MDF (fiberboard) is often much more toxic because of the formaldehyde that is used in some formulations – and there doesn’t seem to be any easy way to tell if you’ve gotten one of the bad 'uns.
I sent a draft copy of the book text to the Last-a-Foam factory for a sanity check. They had the following advice:
- Use a dust mask, a regular hardware store N95 (I think) sanding mask will work fine.
- Don’t do hot wire cutting.
- Spray your work clothes with an antistatic spray (Static Guard, Cling Free) before starting.
The last really works, the dust doesn’t stick hardly at all, you just shake it right off your clothes.
They also recommended a dust table if you do a lot of it.
I just turn on the shop vac with the hose nearby, that catches most of the airborne dust and I also use it to vacuum up any piles I make. When I’m done l lay the hose on the floor, shake out my work clothes, vac off my shoes, and so far domestic peace has been maintained 
But I agree that without the antistatic spray the dust sticks to you like something out of a bad sci-fi movie.
I personally don’t like the feel of the dust on my hands, but latex gloves solve that problem.
All in all, given the strength to weight ratio it provides for a “fun” hull, its waterproof nature, the way it takes resin and filler, and how easy it works I think Last-a-Foam is worth the trouble. But of course, a plug is a different beast from a one-off hull.
Cheers,
Earl
Earl, thanks for the Cling Free info! Polyurethane does have the great benefit, at least for my plugs,of being able to be glassed with polyester and the Cling Free would certainly make the job more bearable…
Doug Lord
–High Technology Sailing/Racing