Thank you for the info. Very interesting details! I'm working attempts at bits of all this into my morning swims partly out of the astonishment of getting to learn directly from writers of this thread!A few remarks - regarding flip turns - there is a difference between fin swimmers and free divers. Freedivers are going for distance - fin swimmers for speed. Chipswim - my best time no-fins dolphin kick is 16 seconds for 25 - i can do it as slow as about 25 and could probably do a little faster than 16 if I worked at it. I don't focus much on sprinting. You'll learn a lot about hydrodynamics by trying to go slow. A good swimmer with one of those little finis mono fins can do 25 in 10 seconds. The record, with a sprint stiffness mono fin - for 50 meters - is a little over 13 seconds.
At 63 I can still manage deep water barefoot starts (with a rope and a boat) . That would be the only time I experience some of the fin swimmer speeds you just described. Found some pictures of them racing on the surface. They leave wakes like boats!
Until I started reading this forum I've been entertaining myself on the bottom of pools where all others are swimming on the surface.... Thought it would look so fun everyone would come down with me but that has not been the case..
.. Yet.
One of the things I thought I needed to discover was an underwater turn which included kicking off the wall. The one that has become usable starts by rolling on one side approaching the wall. Then reaching the wall with the upper hand.... Using that hand to initiate the turn let my butt come into the wall backwards followed by heels so the fin cant catch. With just à few tries rotating back to level and placing feet on the wall happen in the same motion. That dependably sets up a nice position to press off the wall headed the other way. It becomes a fairly smooth gentle turn.
Works pretty slick. Wonder if anyone has experimented with a similar turn. I've put something non skid on the heels of the shoes, and the two screw side of the foot pads because they want to skid if the line up to leave the wall isn't just so. The tips of the flukes and the bottom side of the spring are also contact points but they are already rubber.
