An earlier "sketch" showing the concept:

As I said earlier (February 1, 2013) -- I picked up some wood out of a neighbor's trash this week. I think it's mahogany.

The base is 24 in. wide. The altitude is about 19 in.

Three corner joints have been "lapped" and joined with thickened epoxy. I'm going to the boat show tomorrow (2/7/13), so the epoxy will have plenty of time to cure at 75 degrees F.

With the epoxied joints braced and clamped, I had time to "mock up" the upper apex of the truss.

The inboard (left here) "member" will be a stranded SS wire connecting to the truss with a shackle and closed eye. The wire will run inside a "compression" tube (metal? Schedule 40 PVC?) stiff enough to prevent the truss from tilting inboard when there is no downward moment on the boom. The cable will be terminated at both ends with a SS thimble.

The shroud supporting the boom (and maybe a portion of the skier's weight) will be braided line (sail sheet), running over/in a slot atop the truss, and captured in the slot by an "eye" as shown here. The outboard end of this line will be be connected to the boom just inboard of the "handle" portion of the boom. The inboard end will be "cleated," making it easy to adjust its working length, and thus, the height of the boom above the water.

2/9/13 -- Mocked up the rig again. Makes me wonder if the tension/compression member between truss and tow ring might be steel tube instead of combination of braided wire and tube. Stay tuned.