Foam core in a female mould

[Highwater]

I am looking at building a 12' outboard dinghy. I want to cut the bottom and side panels and set them in a building jig to make a female mould. I want to use epoxy/glass in the mould, then foam, then epoxy/glass. This way I don't have hours of filling and fairing.

What do I coat my mdf female mould with so the epoxy does not stick?

Would laminex do the job better than mdf (but it is expensive)?

Other than vacuum bagging, how do I get a strong bond between foam and glass/epoxy? Use weight, turn hull on its side and use weights?

Can anyone direct me to a plan for a foam/sandwich dinghy of 12' that takes up to 15hp?

Mike

[AndrewK]

Highwater,

Unless you are going to use vacuum I would not bother building a proper mold.
I would make a batten mold with say 5 stations, wire and screw the foam panels in position, glass oneside remove from mold and glass the other. Reinforce the sheer by glassing a timber batten to the outside, install the seating and thats it.
A friend made one using 6mm foam and 450gDB and polyester resin, this has turned out to be an excellent dinghy.