For a scientific article explaining the Strouhal Number, click here.

So why do mor-Fins work better than other fins ? Science is only recently delving into this complicated area. Simply said, the smaller the kick, the more efficient the stroke for the most part, but only when you are sailing. The Strouhal number is the rating that science gives to oscillating propulsion in water. The smaller the number, the more efficient the propulsion. The number comes from the frequency of the kick times the heigth of the kick divided by the velocity of the swimmer. Smaller kicks mean smaller numbers because they mean less drag with the kick.

Other fins function like paddles. Traditional paddle and split fins use “drag” propulsion which creates a void in the water into which they are pulled. Smaller strokes with these fins don't work very well because the void doesn't last long enough to generate decent thrust. They use the longest kick possible such as the dolphin kick, the bicycle kick and the scuba kick (seen on the right hand side of the graphic above). These larger kicks create more drag along with more power so that the drag cancels out much of the power. This feels strong, but is similar to pushing on the brakes and the gas together.

To learn how to do these three new drag reducing kicking stroke techniques, think of keeping your feet in-line like walking-in-place. It is just like treading water. To go faster, you use you toes more like you do in running on land. This kick is slightly larger and almost like a turbo sailing kick for short bursts of speed in currents or to maximize speed.When your kicking stays well within the slip stream produced by the body moving through the water, you create less drag. Less drag naturally requires less effort for similar and even better results. Less drag means that you can swim in currents more effectively and more efficiently. The mor-Fin kick even creates a sense of "flying" through the water because it requires so little effort to move so fast. As you look at the animation above, it does have a fish look to it. Fish hydrodynamic forms moving in fish-like motions... No surprise that it works so well and with so little effort. Sailing/wings let you sail through the water..