Thermo forming foam core

I have noticed recently several production catamaran builders such as Mainecat and HH claim to use a thermoformed foam core and I was wondering how they woul achieve this in a production setting to use in female tooling. I have thermoformed a klegecell core many years ago when building a 24 ft round bilge sailboat out of 4x8 sheets using a heat gun over a stringer male mold but forming a core for use in a a female mold is another story so I was curious if anyone here has any insight into how they are doing it.

Steve.

 

Quite a few builds show guys forming core into female tools using heat guns then screwing the foam to the battens from behind. On those builds they use strips about 16 in wide. On another build I saw them thermoforming what looked to be 2 foot by two foot squares. They were using an oven. I think it would be tough to fit a full 4x8 sheet.

Gurit (corecell) says air blowing on the foam helps a lot. I've been playing with ideas for an oven that uses halogen lights with fans blowing on both sides of foam. Each time you heat corecell to a flexible state it takes more heat the next time around to get it flexible again.

However in a production setting I would thermoform over a plug compensating for spring back so the form sits perfectly in the mold

 

In that video, starting at 44 sec., you see how Falcon catamaran does it.