Ron,
It may have been Eric Sponberg you were thinking of. He has done extensive work with them and, incidentally, favours a stub:
Derek Kelsall has been working on biplane rigs and has shown them to be extremely suitable for catamarans.
Derek is very generous with his advice, and answers emails.
Schionning’s Radical Bay and later seem to have performed OK
Marstrom of Sweden made me a very very nice (stayed) carbon mast. They made it in one piece in a hinged female mould. They used a plastic bladder inside to keep the resin / glass pressed tightly to the mould which it cooked at high temperatures and pressures inside their (very very long) autoclave. Obviously this is not a technique suitable for self build, and even Marstrom had a relatively high failure rate for this technique. I don;t know how they do it now, but I doubt its very different. Ahhh, and its very tricky removing the bag.
Something for wing mast people to ponder. A circular section has a poor coefficient of drag. BUT being round this remains the same regardless of the angle of attack. A wing section has a stunningly lower CD when the angle of attack remains near zero BUT the angle off attack along the height of a mast section varies, soft sails easily deal with this through twisting, but a wingmast does not generally twist very much. I could go on at length but suffice to say that there are some big gains to be had here.
We could also ponder why we might want a wingmast in the first place. For sure an elliptical leading edge is shockingly more efficient than a circular one, but why is this better in a foil ? If Marchaj is to be believed a good deal of it boils down to an elliptical leading edge having later detachment and earlier reattachment at the point where the C/L is greatest and most forward facing. We might wonder therefore if there may be a way in which we could have our cheap(er) circular spar but get it to perform like a wing section. You might ask yourself “What would Bert Rutan do ?” :-)
Some of the NEW Junk rig folks are getting interesting results. If any of them had budgets that exceeded a cruisers petty cash kitty I believe we may have seen a lot of progress. But sadly they seem to all be skint.
There was also a guy in the US who had a pretty perfect twin skinned adjustable sail. You could adjust the camber at each batten, and it was a balanced rig which did not require the multiple sheets of a junk rig. Perfect for a proa. But he just sort of disappeared.
Gary