In the 70's Faralon introduced the Farafin--I think that was what they called it--it was similar to a jet fin but much , much longer and stiffer, and had a special ankle device attached to each fin, that would allow a one way movement for upstroke, and then would lock-out on downstroke so that your ankles did not have to take the enormous torque required to drive the fins. I had these, and even when I could free-squat 600 pounds, the fins were only fast as long as you could bend them--which was an anerobic effort, one that would usually be less than 3 minutes of sprinting...this would vary from person to person--some could not bend them period, and this would mean swimming with stiff boards that offered little forward thrust.
Still today, the forward thrust you get from a fin comes from how much bend you can get from the fin, and how long you can hold the bend in each kick stroke. This is why Freedive fins destroy jets or splits or force fins in a normal scuba dive--say 50 minutes at 60 feet for joe diver. With the freedive fins, you use a very large amplitude, very slow frequency kick--this allows the very long freedive blade to take on a large bend, and to hold the bend for a long time, prior to the next kick cycle. Splits give you an easy bend, but you have to use a high frequency of kicking, with the short ultra flexible split fin--meaning fast leg movements, that also translate into faster heart rates. Jet fins are stubby and stiff, so they require more leg power to get a bend going than the splits, but less leg speed--so total speed can be higher, as you won't be likely to bend the jets to the point that they are beyond maximum bend and no longer effective ( easy to reach with splits or force fins) , but jets require more leg muscle fitness, because you need some leg power to get the bend going, and then receive the thrust. For someone with long term fitness as part of their lifestyle, I see splits as a mistake, and jets far more useful, as you can "train" into them workig well for you....
And then there are freedive fins, which require about the power of splits, and use a much slower kick turnover than the jets. And, by just a slight increase in leg kick speed, large increases in speed occur. For ultra-fit divers, freedive fins come in different stiffnesses, and in carbon fiber, where amazing speeds are possible, still causing the diver to use little actual muscle force, and to be able to maintain very low heart rates--meaning ultra low air useage.
When I dive with divers using splits or jets, I always have to wait for them, no matter how slow I think I am going--due to my carbon fiber freedive fins. I have done tech dives with them where many divers on tekna ( type) scooters were running along a big wreck, and I blew by them with my freedive fins, as if they were towing a boat. I can't blow by a gavin scooter, but I can keep pace with one for 15 to 20 minutes without too much of breathing increase--any longer and it starts to add up too much--and I don't typically try to buddy up with a diver using a gavin if I am just using freedive fins.
Bottom line, freedive fins are so far superior to splits or force or jets that it is ridiculous....I see this as the dive industry NOT wanting to push freedive fins, and I will never accept this. I have many pairs of freedive fins, and anyone who dives with me is welcome to try a pair--and to asee the truth
Dan V
