Fins for Frog Kick

[dherbman]

Why would you extend your legs? Usually legs are kept bent...

No..... Ideally, the knees stay rigid. I once heard an instructor describe it ti students by telling them to "be the Barbie". He wasn't an Aussie.
Check this thread

Actually, wouldn't your legs extend more for the frog kick? Though, admittedly, only for a short period of time.

- ChillyWaters

No.... Take a look at the frog kick video in the link provided earlier. Modified Frog produces even less extension than that of the frog...

 

[djanni]

Having read a little of this thread and after looking at some of the videos at DiveTekAdventures a question comes to mind regarding the two kicking styles. I haven't seen it covered here so far.

In that "perfectly trimed" frog kicking position where the lower leg is kept bent upward at the knee I'm wondering how much drag is created by the legs themselves? With the lower legs held upward, like two little sails against the water, they are out of the slipstream, if you will, and it seems they would create considerable drag.

It makes sense that the frog kick style will produce less silt in heavy silt conditions so that's not relative to this question.

I'm just glad I'm rarely in situations where silt is an issue. Because of that I'm freed and use the flutter kick with my split's. I have less leg fatigue with the split's. Oh, another reason.... I'm not one who feels they have to be in that "perfectly trimed" position all the time just in case someone sees me diving.

 

[ChillyWaters]

No..... Ideally, the knees stay rigid. I once heard an instructor describe it ti students by telling them to "be the Barbie". He wasn't an Aussie.
Check this thread


No.... Take a look at the frog kick video in the link provided earlier. Modified Frog produces even less extension than that of the frog...

Well, I'm not sure what a "modified flutter kick" is compared to the regular "flutter kick", but if you bend your knees and do a flutter kick, I believe your trim will be maintained better, etc. Call it what you will, but I call it a flutter kick.

I started focusing on bending the knees due to having buoyance problems in very shallow water. My centre of gravity wasn't placed right. A few threads I read focused on bending the knees to keep the body in better trim. It seems to have done the trick. No leg extensions, body in better trim, kicking behind me, not silting up much, and no upward thrusts. From what I read, that seemed to be the proper body position for kicking.

- ChillyWaters

 

[dherbman]

As I understand it, the slip stream is shaped something like a cone that begins at the head and the fins stay within this cone.

 

[ChillyWaters]

From what I read, that seemed to be the proper body position for kicking.

Though, if you point is to get from point A to point B as quick as possible, then straighten out, and kick fast. Trim doesn't matter much when you are torpedoing through the water. So, straight legs and hard finning is probably the "fastest" style with the splits.

- ChillyWaters

 

[dherbman]

Not really. Stiff, short and constant is the most efficient method for splits. It doesn't take that much effort, but it has other disadvantages.

Unfortunately, this still produces a "V" of propulsion which directs force both upwards and downwards.

If you could see the force generated while viewing the flutter from the side, there would be a "V" that extended behind the diver.

Here's a short video that should illustrate this. This isn't a silty bottom, but you can still see the effect. Click on the image to follow the link to the video.

 

[ChillyWaters]

Here's a short video that should illustrate this. This isn't a silty bottom, but you can still see the effect.

First off, that's the worst video ever.

Second, the diver uses erratic finning that shows nothing. He looks to often take very large finning strokes, which isn't the proper style to use with split fins. Even later in the film you just see a bit foot come into view, which shows that he isn't donig the smaller kicks as is suggested with split fins. Thus, the video is of no absolute value.

Third, I'm sure the type of split fin would have a lot to do with the where the force of the water is directed. A very hard split fin would work like a paddle fin, I would imagine.

- ChillyWaters

 

[SparticleBrane]

I'm just glad I'm rarely in situations where silt is an issue. Because of that I'm freed and use the flutter kick with my split's. I have less leg fatigue with the split's. Oh, another reason.... I'm not one who feels they have to be in that "perfectly trimed" position all the time just in case someone sees me diving.

Where do you dive that silt is not an issue?
When I was diving on the Benwood earlier this year with a group of essentially new students, we had ~80ft of vis when we first hopped in. It was great! All students were frog kicking so the vis didn't degrade at all--until a group of about 6 divers from somewhere else hopped in. They flutter kicked around the whole wreck and soon the vis dropped in half.
While flutter kicking might not immediately affect YOU, since the silt is kicked up behind you--it makes the people behind you mad.

Another example--in May I was diving in a quarry with a group of brand new students on their first open water dives. I had a pair of new students and we were doing a navigation section. There was a group in front of us by about 10ft, with one diver who hadn't quite mastered trim/frog kicking yet. He never held his feet up so he kicked up loads of silt everywhere. My team literally had no need for a compass because we could have just followed this giant cloud of silt to our next waypoint.

 

[dherbman]

First off, that's the worst video ever.

Second, the diver uses erratic finning that shows nothing. He looks to often take very large finning strokes, which isn't the proper style to use with split fins. Even later in the film you just see a bit foot come into view, which shows that he isn't donig the smaller kicks as is suggested with split fins. Thus, the video is of no absolute value.

The vid is shot at 75' in available light and compressed. Yes, it is bad. Yes, it is bad finning tenique. However, it does illustrate the blast patter of the kick. The fins are never directed directly at the bottom, yet the force is spread out and the result is silting.

Third, I'm sure the type of split fin would have a lot to do with the where the force of the water is directed. A very hard split fin would work like a paddle fin, I would imagine.

- ChillyWaters

lol Who makes a very hard split fin?

I've addressed your misconceptions and given some very solid explanations. It's clear you would rather cling to your misperceptions, rather than open your mind to reality. This is not meant as a dig or an insult, merely an observation. I suppose making erroneous statements might be your way of asking questions, but they beg for correction.

 

[ChillyWaters]

The vid is shot at 75' in available light and compressed. Yes, it is bad. Yes, it is bad finning tenique. However, it does illustrate the blast patter of the kick.

Ummm... then how can you show it as proof that a proper technique doesn't have much of a "blast pattern" ??? That's extremely poor logic.

The fins are never directed directly at the bottom, yet the force is spread out and the result is silting.

No, but they aren't doing the proper finning for a split fin, thus the video doesn't address the point.

lol Who makes a very hard split fin?

From my understanding, split fins can be bought with varying degrees of softness/hardness.

I've addressed your misconceptions and given some very solid explanations. It's clear you would rather cling to your misperceptions, rather than open your mind to reality. This is not meant as a dig or an insult, merely an observation. I suppose making erroneous statements might be your way of asking questions, but they beg for correction.

That's just sad. You make erroneous comments, throw up a bad video to prove your point (which you admitted shows poor finning technique), and you think you've made a proper point... hahahaha... You're no scientist, eh?

"Look, here's a guy with split fins, and he causes silting... sure he isn't finnnig properly, but hey, he has split fins on, so therefore all finning with splits much cause silting... honestly, I have a point, somewhere, but I just can't muster it up... "

I'll wait for someone else to respond with actual valid points before I continue in this thread.

- ChillyWaters