Alan,
I found something on the North Sails site (see link below) that said that the problem of jibing with a tack strap would result in the strap always being twisted on one jibe. This makes absolutely no sense to me, but is thoroughly consistent with my experience. If I set on port tack, the strap will be twisted on starboard, but then straightens out again if I jibe back. Why the strap doesn't swivel instead of twist I have no idea.It seems the solution is to toss the tack strap into the deepest recesses of a lazarette, only to bring it out if I'm planning to broad reach for at least three hours without any chance that I'll actually jibe.Unless, of course, someone out there has figured out how to rig the strap to beat this problem.