There’s usually some esoteric (obvious to some of
> you) mechanism at work when I play at designing these things. Can anyone
> help?

Tom--I can't help with the engineering, but perhaps can point you to some resources. I thought that I read a review or report on wing paddles within the last couple of years in Sea Kayaker magazine. When I checked the index, however (see link below), I did not find it. It may be in one of the articles discussing paddle features, or light weight paddles. Or, I may have been reading Paddler, or Canoe and Kayak. Anyway, I seem to recall that the review said the Wing required a certain technique in order to take advantage of the benefits. I think that all flat-water racers use wings. Perhaps you need to change your stroke to avoid the twist. The article concluded that the wing was not the greatest seak kayak tool because of the special technique and because of the increased difficulty (and decreased efficiency) in using a wing for bracing, draws, sculls, back paddles, etc... Look under "paddling" in the Sea Kayaker index and you will find several articles that may be worth reading as you experiment with paddle design.

Last summer I took a 2-day course taught by George Gronseth (author of Deep Trouble, and several of the paddling technique articles in Sea Kayaker). He is not shy with his opinions, and many in the kayak community may disagree with some of his views (is it something about the name George?), but his opinions were usually backed up with some solid reasoning. Anyway, he paddles with a flat, symmetrical blade, because he does not believe the small amount of extra efficiency in a cupped or asymmetric blade compensates for the increased inefficiency of those designs for bracing and other strokes. I haven't used enough different paddles to say that I have a preference.