Air mold (cylinder molding)

In the end of the page about "Cylinder molding" the concept "air molding" is mentioned:
http://www.multihulldesigns.com/pdf/cm/CYLINDER MOLD MULTIHULL CONSTRUCTION.htm

I assume that this method would mean starting by putting two lengths of boatlong plywood sheets in a vacuum bag, with epoxy between them. Then bending the package between two boatlong 2-by-4's, allowing the sheets to form a constant radius, which can be adjusted by the distance between the beams. Then applying the vacuum and letting it cure.

I guess the hulls are then built like in cylinder molding method by cutting the radiused panels to the shape of a hull, stitching two halves together, and attaching stringers, bulkheads, and deck.

Does anyone have experience with a method like this?

It appeals because of simplicity and lack of unnecessary fabrication.

 

If you are looking for a simple method and can live with the limited shapes they produce, maybe look at Constant Camber.
http://www.searunner.com/index.php/designs/constant-camber-designs

 

The air mold would be a lot easier than cc, if I understand it right that you have to make a mold and then build the hull by gluing a lot of thin sheets together.

The air mold would be very much quicker. But also more limited in possible shapes.

 

bjn,

I think it would be worth your while doing some greater research, the CM & especially the video are pretty wow check it out kind of stuff, there's plenty info on here from accomplished charly build , a thrown away hull sets due to quality by catbuilder aka ocean/navigator/hero plus a couple other sock puppets and maybe a planned build by another. The marketing blurb from kurt is just that- in putting the best light on his preferred method is just one way to skin a cat, other ways include flat panel topsides teamed/joined with a molded canoe body- this method is to my mind the best compromise between investment in tooling/frame set up and finished hull shape, a few semi production kit builders use this approach along with some larger racing vessels, deck edge treatments affect the look and styling to a greater degree.
All the best from Jeff.

 

I've heard about the air mold concept but I'm not sure a boat has ever been built that way must ask Kurt about that. There have been plenty of CM boats built though it's not a magic bullet you still need to do the remainder of the work to make a finished boat. Plenty of boats make it to shell stage and are abandoned when the enormity of the work remaining comes into focus.

 

I had sent an email to Kurt with my question. I read later on his blog that he was complaining about getting hundreds of emails during a short vacation. So I guess my email was filtered out when reading and responding to all those emails.

Might be fun to try it myself anyway. But if I ever will, I don't know.

 

Kurt published a little article about his air mold on the multihull blog:

http://multihullblog.com/2017/04/the-air-mold/

 

Nice. So the airmold really had a mold, but only for the bottom radius.

 

Now I understand, really for the sake of the small effort in continuing the forms and at least a way to define the "sag" at the upper edge of the molded panels seems to layer another element of risk to an already wild west method, we know the cylinder mold works as is in at least gives an edge of predictability and a reference at the sheer line edge of the panel... imagine the disappointment of an unfair panel.. or the scarfs not shuffling together correctly mid panel.
Jeff.

 

I'd imagine that only experienced builders would choose that method but I cant see much labor saving in the air mold versus a standard segmented mold. You need to set them up in a similar way so the work is virtually the same and you only use cheap ply for the mold cutouts anyway so it's not really a big saving. I had my segments cut out on a CNC table so they were all identical.