Cylinder mould construction anyone built and finished a boat with this method?

[Corley]

Hi,
Just recently I was looking at buying Kurt Hughes Formula 40 in the states since then the syndicate with which I was looking at buying the boat has collapsed and I'm back to square one.

I've been doing some research on cylinder mould technique for building and it seems like a good approach for building skinny trimaran hulls at a reasonable cost. I'm very comfortable with working with ply and feel I've developed some reasonable technique with tortured ply I also have a workspace thats flat and level and can control the temperature if necessary.

I'll probably arrange to have my ply scarfed in advance by the supplier if the price isnt excessive once everythings organised I'll setup a build blog.

I guess my question is has anyone built a boat to completion using this method and how did it go? What would you have done differently?

[CatBuilder]

You will have to scarf it yourself, as its 12:1. Will comment more tomorrow.

[Corley]

Hi Cat, I'm not worried about scarfing my own ply I'll just set up a scarfing jig as detailed in Gougeon brothers on boat construction.

[CatBuilder]

Hey Corley.

Sorry for the delayed response.

The Gougeon scarfing jig doesn't work for 12:1 scarf joints on 3mm ply. You have to stack them up in a stair step and grind them down. That's all in Kurt's instruction book.

I had some trouble with this method, since I'm not a "wood guy" by nature.

I didn't understand how the materials would behave. I'm sure you'll do much better with that than I did, having some wood working experience.

The hull panels go up very quickly compared to a foam/glass build. You have them done in a matter of a couple weeks. Of course, then you must get them into shape, pour a keel, install bulkheads, etc... like a normal build, but the hull panels go up lightning fast.

What I would do differently is try a short practice panel on the cylinder mold before doing the real hull. Vacuum bag it down and try to create a little section like the real hull. It might help work out the kinks and stress associated with having half a hull go up in a single epoxy setting window.

Also, watch the bag very carefully. I had a tear in the bottom of my bag under the panel, where you could not reach it. I lost a half a hull that way. So, be gentle with the bag and don't let it tear.

Also, when moving the half hulls around the shop, get an army. Well, my half hulls were 50' long and about 7' wide. They were hard to handle with 4 guys. We could have used more people.

[cavalier mk2]

I'd recommend stair stacking but using a electric plane then a flat sander for the scarf joints.