I'm interested in making a plug, than a female mold with parting plane
and flange to make several canoes for our club. My plan is to lay out
the strongback, attache the stantions, cover the stantions with
flexible foam strips (like a strip built canoe), cover the foam with
spackle and sand, wax with releasing agent wax, and lay up the
fiberglass mold cloth. I read in a book how it is possible to make a
plug with spackle dried and sanded.

My questions are what would be a good foam sheet thin enough and
flexible enough to strip over the stantions. Secondly is is spackle a
sufficient finishing material, and finally when making the parting
plane and flange do I have to account for shrinkage. I haven't decided
if to make the parting plane travel the length or width of the canoe.
One canoe manufacture goes length wise while another goes across the
width. A flange is neccessary for my mold because the canoe will have
tumblehome (cuts in at the sides) and will not lift out of a
conventional female mold. Any thoughts would be really appreciated.
I've read everything I can get my hands on with no luck. Oh yeah one
final question, is there a realease agent tape I lay in the female mold
to cover the seam on the parting plane.