T.C.
Contributor
Actually, it's a Del-Fin.come on, that's clearly a force fin
Delfins-Predator-Power-Fins
I use them. Best of both worlds.
Split Fin Bashing?
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Delfins-Predator-Power-Fins
I use them. Best of both worlds.
Yes, and I have heard that they are more efficient when you have more knee flexing than with the normal more straight-legged flutter kick. I have never tested it myself.
The reason you don't see many recreational divers using those kicks is because they don't know how they are done and when they can be used effectively. On a whole lot of dives, there is no point to them, but they can be very nice in a lot of cases. Here are two examples:
1. I just came back from Australia, where two buddies and I got in a bunch of dives. On one of them, we were led by a DM, who was going to show us a great swim through. It really was pretty good--long and turny. Neither my friends nor I got a decent look at it, though, because we went last, after the flutter kickers (including the DM) had churned it all up. If we had gone through first with our frog kicks, at least some people would have had a good view of the interior.
2. I was doing a dive in Hawai'i (Ni'ihau), and we went into a very large room in a swim through. The DM pointed to a corner where there was a very rare endemic lobster hiding out. I was the closest, so I frog kicked in close to it, where the ceiling sloped down to the floor. I got really close, with my chest a few inches off the floor and my head just below the ceiling. I wanted to give everyone else a chance to look at it, so I back kicked until I had more space between the floor and the ceiling, did a helicopter turn (which means you turn around while staying on the same horizontal plane and keeping your belly button in the same place while you turn), and moved out of everyone's way. No one else could get close to it. Back on the boat that is all people wanted to talk about--could I show them how to do that?
Ask, and ye shall receive...
---------- Post added May 16th, 2014 at 06:03 PM ----------
The more important question to ask is "How many times do you see vacation divers in situations where they - or the environment, or other divers - would benefit from their ability to use those kicks... but they do not or cannot do them?"
The answer to that is "All the ****ing time."
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I wear them when just messing around--my dives are rarely anything but benign. I think I can go faster in a straight line and little/no current. If they make kicking easier that's good for me since I'm prone to cramps in the legs (among other places). I won them at a treasure hunt. Only problem so far (6 years/maybe 300 dives?) was that one of them SPLIT (replaced free at the shop). I do use standard fins when DMing, I guess for the rescue possibility, so some say. Thread started today and 42 posts. Much like the snorkel threads--lots of posts on something not that vital.
freewillie
Contributor
Point taken. But, they might need to or should be able to, I was referring to actually using those kicks. Most of the time they are in situations where they would or should and simply don't or can't.Ask, and ye shall receive...
---------- Post added May 16th, 2014 at 06:03 PM ----------
The more important question to ask is "How many times do you see vacation divers in situations where they - or the environment, or other divers - would benefit from their ability to use those kicks... but they do not or cannot do them?"
The answer to that is "All the ****ing time."
K
KeithG
Guest
from an engineering / physics point of view split fins are crap. Kind of like the wet noodle of diving.
IMHO that is why a large part of the sentient world bashes them.
IMHO that is why a large part of the sentient world bashes them.
C'est le vie.
Or maybe not.
Or maybe not.
DaleC
Contributor
Split fins simply bleed off flow over the blade. They're not that scientific. You could achieve the same thing by cutting half the length off a paddle as well (which swimming pool training fins do). Flow over the blade translates into forward momentum (or thrust). That's why you need to kick more with splits to achieve the same momentum, you are just generating less thrust.
The amount of thrust you can generate depends on how much resistance the divers foot, ankle, calf, knee can tolerate, both for a single kick cycle, and for a sustained kick rate. The divers leg is stabilizing the thrust generator.
A loose analogy would be the sail and mast of a boat. The sail could be huge but the boat can only accept as much thrust as the mast can bear. Splits represent the solution of putting on an overly small, or torn, sail instead of strengthening the mast.
People with weak legs (no negatives intended) find the resistance created by the blades travel through the water too taxing to stabilize and prefer splits. They seek less kick resistance (and consequently more repetitions) even though it equals less thrust. This is most prevalent in vacation or occasional divers who don't dive enough to strengthen the specific muscles used for diving.
When I first started using Jets my feet would hurt and/or cramp up quite often. This subsided once they became conditioned to the work load and to a more efficient kick. This boils down to not resisting the load at the foot, but letting it be borne by the leg proper. Fish, like tuna (which don't have split fins -they have two, very wide and shallow blades), have small caudal peduncles but generate terrific thrust by transferring the load to both lateral flanks. The flanks do the work, not the tail joint.
A part of championing splits also comes from a natural reaction of people to justify their actions. Newer divers get "sold" on the idea of splits as an innovative solution, pay a lot for them, and then feel they need to defend their decision. Not many want to say "I paid a bunch of money for a sub optimal fin". Without strengthening their legs by using paddles long enough, how would they know the difference they could make.
The amount of thrust you can generate depends on how much resistance the divers foot, ankle, calf, knee can tolerate, both for a single kick cycle, and for a sustained kick rate. The divers leg is stabilizing the thrust generator.
A loose analogy would be the sail and mast of a boat. The sail could be huge but the boat can only accept as much thrust as the mast can bear. Splits represent the solution of putting on an overly small, or torn, sail instead of strengthening the mast.
People with weak legs (no negatives intended) find the resistance created by the blades travel through the water too taxing to stabilize and prefer splits. They seek less kick resistance (and consequently more repetitions) even though it equals less thrust. This is most prevalent in vacation or occasional divers who don't dive enough to strengthen the specific muscles used for diving.
When I first started using Jets my feet would hurt and/or cramp up quite often. This subsided once they became conditioned to the work load and to a more efficient kick. This boils down to not resisting the load at the foot, but letting it be borne by the leg proper. Fish, like tuna (which don't have split fins -they have two, very wide and shallow blades), have small caudal peduncles but generate terrific thrust by transferring the load to both lateral flanks. The flanks do the work, not the tail joint.
A part of championing splits also comes from a natural reaction of people to justify their actions. Newer divers get "sold" on the idea of splits as an innovative solution, pay a lot for them, and then feel they need to defend their decision. Not many want to say "I paid a bunch of money for a sub optimal fin". Without strengthening their legs by using paddles long enough, how would they know the difference they could make.
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Finneli Felwitch
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