Andrew,
I did the inverse: used the plug to create a mold then cast boats inside the mold. Here are a couple of things to keep in mind:
1) you want the top to be slightly larger than the bottom so they will fit together...or have some other method of joining. To do this, we cast the bottom, added 1/4" of putty around the gunnel then cast the top.
2) waxing is your friend...the more you wax the mold/plug, the more likely parts will come off it!
3) coat with pva or some other release agent to keep the boat from sticking to the plug/mold
4) poly resin isn't water proof, so you want a gel-coat exterior to prevent seepage through the layers
5) We layed our boats in the following order (outside to inside of the boat): wax...6 coats, pva (let dry), gel-coat, let dry to tacky then a couple layers of glass mat and finally heavy woven roving I believe the mat was 1 oz and the roving was 18 oz.
With my design, the bottom slides inside the top and once they are glassed together, it is VERY rigid. A true layout design will likely need some support for the decks.
I can dig up better info if you need it
Scott
