Yesterday I joined Hackerspace ATX and worked on the 7th prototype of the Merfluke. The main difference between this and the Mark 6 is improved pedals. Today at 11:30 I went to the Hackerspace but nobody was there---I need to become an associate member so I can get in.
Nonetheless, today I completed the new pedals and reassembled the Merfluke Mk 7. This weekend I will give it another test run, probably in Lake Pflugerville on Saturday afternoon. If there are no major problems I will try to time myself swimming a few hundred meters, and perhaps I can get my wife or some volunteer to video tape me swimming---I would love to be able to analyze my technique, since it is entirely possible small changes could make a big difference. I doubt the water is clear enough to show much, but anything is better than nothing.
I am reasonably confident, based on prior experience, that the Mark 7 will be better than the Mark 6, but probably will not approach the speed with which I can monofin.. I hope at least I can acheive the speed at which I can swim freestyle unaided.
Here are some photos of the Mark 7.
This is a side-on view---my body would be to the left, with my shins embraced by the white soccer shin guards and my feet on the ugly orange pedals, which are more hydrodynamic and lighter than my last ones.