Spackling past has absolutely no sear strength. If your plug flexes at all
it will crack. Also remember that any imperfection in the plug will be
reproduced in the final product.

I would think about something other than foam for the base. Possibly narrow
1/4" plywood strips. Sand as fair as possible, cover with 2oz scrim cloth
and skim coat it with a thin coat of fairing putty. Sand it very fair to
about 240 grit and spray a couple of coats of Duratec surface primer. Wet
sand with some 600 grit. Now split the plug down the keel line and mount
your moldboard. You want that parting angle as sharp as possible. Polish
the daylights out of it starting with rubbing compound and ending with
McGuire's machine polish. Once you can see your face in it when it is dry,
wash it down well and let it dry over night. Spray a very light mist coat
of PVA followed by several light coats. PVA is very thin so try to avoid
runs by making several light passes rather than one or two heavy coats. Let
it dry for several hours before spraying the first gel coat layer of the
mould. I would strongly recommend a tooling grade gel coat rather than the
normal stuff.

On the hull lay-up I wouldn't worry to much about the part line if it is
tight. You will get a little gel coat seeping into it. Just sand off the
flash and polish out the gel coat.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Douglas" wrote in message
ups.com...
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.