Definitely part on the centerline. It will be extremely hard to strip out
the molds if you use a transverse parting line which will make it easy to
damage them. To handle the fine entry and exit carve bow and stern stations
out of 2x4 blocks and offset them inward so the strips run out over them.
The mold boards should be VERY flat and sturdy. 3/4" Melamine surfaced
particleboard is what I use but for the length of your hull you should
probably also reinforce them with some framing. A couple of coats of a good
paste wax will keep the resin from bonding to the melamine.
Build your station molds in two halves with a good strongback for each side.
Add some dowel pegs to keep both sides aligned but still be easy to split
apart. The key is that both sides have to be stiff on their own. If they
warp even a little while being split or mounted on the mold boards you will
never get your final mold halves to line up. Once you have mounted the mold
boards drill through the original alignment peg holes and fit the two
halves back together lining up the holes. Then drill through both mold
boards at several places outside the plug. Split it apart again and install
short pegs in the new holes. These will serve as alignment points to bolt
the mold together. When building the mold be sure to add plenty of external
reinforcement so the halves are very stiff.
Keep in mind that vacuum bagging a female mold is a lot harder to do than a
male mold. If you are using polyester, forget vacuum bagging altogether.
You will not have enough working time to seal the bag. If you are going to
vacuum bag, seal the mold flange with a soft putty but do not let it get
inside the mold. Much easier to sand off the flash than refinish the hull
surface. You will need a very high elongation (stretchy) nylon film to
get an even pressure and clamp over the vacuum tape to keep it from pulling
away. Poly sheet like I use will not work. It will not stretch enough so
you will get bridges. If you try to leave to much extra material the pleats
will be almost impossible to seal. Pull the vacuum to 20" or more to
stretch the nylon and still have enough pressure on the lay-up. You have to
be careful here because you will have more force on the topsides than at the
keel. You have to find a compromise vacuum so that the keel is consolidated
without squeezing to much resin out of the sides.
--
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" <lgsumr.RemoveThis@yahoo.com> wrote in message
news:1162036954.046485.52120@h48g2000cwc.googlegroups.com...
> Some follow up questions for my canoe plug and mold questions. Thanks
> guys for the previous solutions. Would masonite make a good parting
> board material and what would I use on it for a release agent. Also is
> it glued to the mold until the fiberglass cloth is layed up against it.
> For running the parting line down the keel line I thought it may lead
> to to difficulties in making a flange at the parting line on the female
> mold because the bow and stern come to such a narrow edge. It seems a
> flange running across the mid section of the canoe mold would be easier
> to build up a flange. Finally would a special putty work by smoothing
> it into the parting line within the mold instead of having the resin
> seep in here. Also we are going to vaccum bag these canoes for our
> club, so I thought perhaps the mold will have to be completly air tight
> at the parting line by using the putty. Thanks guys for the help. There
> really isn't any reference out there for these building techniques. I'm
> sure these are advanced techniques but we are can do guys and want to
> make a really good canoe
>
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