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Re: Catmaran kayak? I have one --- almost *LINK*

: Btw, I have identified a potential problem building this thing SOF. Since
: it's an asymetrical hull, the stringers won't tend to keep the hull
: straight, more curve on one side will tend to want to pull the other side
: to a curved shape that you won't want. Once the joints are epoxied this
: shouldn't be a problem, but keeping it straight until the epoxy hardens
: will mean you'll likely need a special building jig. Perhaps laminating
: the stringers from thinner stock would help? The solution to this I'll
: likey find as I build it. I've also thought that gussets between the
: frames and the stringers on the hull's outsides may make building it
: easier. Can be very light ply gussets, done often in aircraft construction
: which is very similiar to this method.

: Bill H.

Bill - yes I confronted this problem in the model. I attached the chines to the hulls individually, but the hulls picked up some curvature from my not-very-flat dining table. Lack of inner chines (the model has ply inner faces) meant there was no opposing chine tension to hold the hulls straight, so they were also kind of floppy. To solve this, I clamped the two hulls together and added diagonal braces (bamboo skewers) while clamped straight. The result was pretty amazing, dead straight hulls with very little flex. They look and feel like fat model airplane wings.

I like your idea of gussets, and they may be enough stiffening to avoid using the diagonal bracing. If I could find resin-impregnated paper tubes like we used to make airplane fuselages when I was a kid, I think they would make good braces, but gussets would be better. I think it will help to have at least one chine on the inner wall to help balance the outer chines, and ply walls will add little flex resistance in the lateral direction unless they have a good vertical camber - seems like this will take a great deal of work the first time through, but may be the best in the long run.

For building the prototype, I plan to jig the hulls together as in photos 34 and 40 at the link below. Even though the inner hulls on the full-size boat are not flat, I'll use spacers to hold the bulkheads a couple of inches apart for the build - this will allow the outer chines of the two hulls to oppose each other until the frame is pegged and glued. It should be almost like building a regular boat, plus the bulkheads will definitely be at the same location, you can use your eye to judge symmetry, etc.

BTW - I forgot to ask - I was going to buy 1/2" marine ply for the bulkheads, does that make sense to you, or should I just get birch ply? Thanks, Carl

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Catmaran kayak? I have one --- almost *LINK*
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost *LINK*
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
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Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
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Re: Catmaran kayak? I have one --- almost
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Re: Catmaran kayak? I have one --- almost *Pic*
Re: Catmaran kayak? I have one --- almost
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