Good afternoon to all,

I am building a female mold that will beused to make a carbon fibre marathon canoe (18’6”). I have good skills working with fibreglass but this is my first experience in making a femalemold.

The mold is based on wooden slats lined with 1” foam and  lined once more with fibreglass. The fibreglass  is then finished with the usual body fillerand mold primer/hi-gloss coats to make it a glass finish. As you may realise,the front and back end of the molds are extremely streamlined and I find itimpossible to sand down to a glass finish.

The alternatives that I have come up withwould be to 1) cut the mold in half and work on each side separately thenreassemble to lay the carbon fibre cloth. The disadvantage might be that Iwould not end up with symmetrical sides. Option 2 would be to lay the carbon fibrein the mold as is but finish the exterior of the canoe’s ends to a glass finishafterwards. Finishing the outside to a glass finish after unmolding seemsdifficult to achieve. Any comment and recommendation would be welcome. 

Manythanks.

Z

I would definitely part the mold in two halves. It will make layup and de-molding much easier..

As to the symmetry, I would polish up and shape one side, then do a few "templates" by simply laying up a few narrow strips on the finished side, reinforce them to make them hold the shape perfectly, then use them to shape and polish the other side. (A bit like making one-sided rib for the canoe)

While it is a lot easier to polish up an outside surface, having a mold with as good a surface as possible, makes it much less prone to release problems, a definite worry with a CF shell to remove form the mold!
A demolding problem could become rather expensive ...

Have you given any thought to the types of CF cloth to use? I would recommend using a CF/Kevlar mix for the outside, to get a good impact resistance.




Good luck with the project .. 




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