Howdy all,

In the last episode, Paul Jacobson challenged me to keep playing with conduit PVC. I've done so, and have two things to report and some questions to ask.

1. I've successfully bent conduit PVC. My method was to fill it with hot sand (heated to ~300 degrees F in our oven), then use a heat gun to make it pliable in just the right place. I hammered some nails about 2.5" apart on a piece of plywood in a rough 12" diameter circle. Then I slowly bent the PVC around the circle. Result? A very sturdy and primitive looking proto-rib! A 45 degree bend joint added to the ends and presto, Chester, I've got a complete rib. Time involved to do it was roughly 20 min., but with increased efficiency, I think a rib could be made this way in 5-10 min. easy.

Okay, so I can make sturdy ribs now. What about longitudinal rigidity?

2. As you may recall, Paul encouraged me to look at Putz' boat, and to think about how to build the longitudinal "trusses" that would provide longitudinal rigidity. Since I'd prefer not to do lots of cutting and gluing of the triangular pieces (name?) in a classic truss, I played with the suggestion that I use a sheet of more rigid material secured to the PVC pipe, in effect creating a kind of I-beam. PVC sheet stock was available locally, but I remember that I've used it before in lattice form on a fence, and the stuff really bends. So I bought some 1/4 luan plywood instead (quite a bit cheaper, too!)

Paul suggested that I might fasten the plywood to the PVC with screws, which remains an untested option. Instead, I made a roughish lengthwise cut in the PVC pipe with a drill saw. This was kind of hard to hold straight, so my cut wasn't at all square, but wandered some. Nevertheless, I've successfully made and assembled a 4'X 8" I-beam with 8" wide plywood jammed into PVC pipe at the top and bottom edges. This appears to be quite strong enough and rigid enough to do the job.

Now some questions:

1. How to secure the longerons (right word?) to the ribs? I've thought about cutting a larger piece of PVC in half lengthwise (so far I'm using 1/2" pvc, so let's say here I'd use 1". Then take a 1" piece of this and gluing it horizontally to the outside of my vertical rib. This would provide a place for the longeron to nestle, and support the joint. Then I could drill through the longeron and the rib to have a hole into which to place a clevis pin. Thoughts on this? A better, stronger way come to mind?

2. Is there a better way to construct my PVC pipe/plywood "I-beam"? I want it strong first and then secondarily easier to build. I haven't yet glued my prototype. Any recommendations of a glue to use to join PVC and wood (the PVC solvent did nothing but give me a mess to clean up).

3. My thought is to get Putz' book and create real size plans on paper, then place them on a piece of plywood and use nails around the perimeter about every 1.5" as a guide for making my ribs. Anything more elegant come to mind?

4. I want the kayak to be able to carry about 250 lbs. (Me + an easy week's worth of food and gear). Could I reasonably expect the Putz boat to do this?

5. Are there other designs I should consider?

Could a reasonably sturdy and cheap folder really be possible?

Ad delirium,
Wayne