: My build is simpler than yours because its not a folder. I simply
: used Tom Yost's method for laying out the frames for his
: folders. The holes drilled in the edges of the frames provide a
: recess for the tubes to sit in. The tubes will be epoxied to the
: plywood frames and then lashed.

: With your method of running carbon fiber through aluminum tubes I
: would worry about electrolysis. Aluminum is supposed to corrode
: when it contacts carbon fiber. You may need some kind of sleeve
: to prevent direct contact. Or perhaps some kind of plastic tube
: instead of aluminum.

If I listen to Tom's directions with stress on easy and quick assembling/disassembling, then there won't be contact outside the time on the water, but I've taken a note and will keep a look-out for the corrosion. An inner plastic-tubing could do good as for the 'sharp-corner' breaking.

: Torsion is twisting along the longitudinal axis. Imagine the
: right-hand side of the bow twisting up as the left-hand side of
: the stern also twists up. Obviously the left-hand side of the
: bow and the right-hand side of the stern will go down. This
: could be caused by paddling diagonally into large waves.

My outset will be to use days with flat water, but it will eventually have to face some tougher water.
As for the twisting .. I like the snap-on approach, but I'll have to use some bracket that grips well around the keel. If it has a good tight grip two neighboring sections shouldn't move relative to each other and the twisting will lie in the longitudinal structure. A swell moves in two directions (back and forth at top and bottom), but it does not resolve into a real twist. The oblique boyency would do some twisting though .. . As of the current design, nothing grips on the carbon and it will only take pushes from the sides.

The rigidity lies in the keel, and not really anywhere else. To prevent the 'twisting' that may occur when crossing a swell I could lock the keel-sections and all that attaches to it. To get a lock that performs well I have wanted to ask you all weather any of you have experienced that:

say a hole drilled through a telescopic tubing to be fixed with a pin .. to what degree does the hole wear and tear against the pin and thus grow into a slobby lock?

If I lock the keel-tubes this way the slack of each lock can add up. The constant wiggling of the keel on anything else than flat water ... doesn't that stress such locks a lot?

: An
: ordinary kayak is built strongly enough to resist torsion, and
: wood gunwales and stringers can tolerate some twisting, but
: ultra-light kayaks can twist quite a bit and this can cause
: sudden and catastrophic failure of pultruded carbon tubes. Platt
: Monfort designed a series of ultra-light small boats and used
: diagonal reinforcements with Kevlar roving to prevent torsion
: (www.gaboats.com). Clearly this method is not readily adaptable
: to folders.

I'll expect that stringers might break, but not fall apart (in two pieces), and that brackets and 'stuff' will bend or deform, but not splinter apart ... not that it gives much pondus to security anyway ;o/
If I allow the boat to flex, I'll be working with the elements, not against them .. "The sea-worm" .. but I should expect it to be more flexible than the average boat. I've thought of a couple of ideas to forego the flexing, but they probably sacrifice storage.