[Fondueset]

Dave, thanks for your insights. This weekend we'll try for some footage coming up off the bottom - The water here is now 64F so I'm in my 3 mil with less weight - the real test would be the dead of winter in my 6 mil with a full load.
Viz has been mediocre lately - with ridiculous boat traffic so we did limited footage.

I know what you mean about the loss at the end of each stroke and have much more of a sense of resistance with my hard waterway - but the Hyper fin is much much faster with way less energy output. My dive buddy can normally keep up with me when I'm cruising in my waterway (with his C4 bifins) but he has to exhaust himself to stay with me in this fin when I'm just cruising at a moderate pace. The actual performance sort of flies in the face of how it feels.

What you seem to be describing sounds like the Leaderfins Free Flyer - or Flyer model where they've moved the blade back. The problem of maintaining thrust through change of direction is an interesting one.