Folded Knees

[Ayisha]

can anyone comment on the differences in finning technique?

Here is Trace Malinowski doing the modified flutter and frog kicks. It might be easier through videos:



Here is @johnkendall demonstrating finning techniques:

 

[ginti]

That's exactly that. I don't say that my thighs and calves are aligned as if it was made of one piece of wood. It is the 90 degrees that I find unnecessary, unnatural and inefficient if you want to move fast. But I agree it's sleek, pretty much tech diver style .

I am even more curious about seeing a video at this point. The way you are describing it, you may well have good trim and position in the water. Without a video or a picture, it's hard to say...

 

[Dody]

I am even more curious about seeing a video at this point. The way you are describing it, you may well have good trim and position in the water. Without a video or a picture, it's hard to say...

I will post it tomorrow.

 

[ginti]

This is a screenshot from the third video posted by @Ayisha, minute 0:35. John here is not moving, yet the legs are net at 90°deg, but slightly less:

Another screenshot here:

I wouldn't be obsessed with having a perfect 90°deg angle at the knees, I am not even sure if that has advantages or not (with a perfect 90°deg angle, the feet would be too high and would create drag)

 

[Ayisha]

That's exactly that. I don't say that my thighs and calves are aligned as if it was made of one piece of wood. It is the 90 degrees that I find unnecessary, unnatural and inefficient if you want to move fast. But I agree it's sleek, pretty much tech diver style .

Your newest post is very different from the parameters of your original post, ex "a straight line" with your "fins, calves, thighs, aligned":

...my trim is better with my entire body on a straight line, my fins, calfs, thighs, aligned.

So now it's 90° calves that you find inefficient? Every body is different. Some very tall people can raise their shins straight up and be perfectly proficient. Some short divers can barely raise their fins and be perfectly proficient. A shorter diver can be more affected by the position of their limbs. It depends where your fulcrum is and how you've weighted yourself.

I don't believe that trying to have a 90° angle is a "thing". Some degree of a bent knee is required to perform the various kicks, and varies from person to person.

 

[Dody]

Your newest post is very different from the parameters of your original post, ex "a straight line" with your "fins, calves, thighs, aligned":



So now it's 90° calves that you find inefficient? Every body is different. Some very tall people can raise their shins straight up and be perfectly proficient. Some short divers can barely raise their fins and be perfectly proficient. A shorter diver can be more affected by the position of their limbs. It depends where your fulcrum is and how you've weighted yourself.

I don't believe that trying to have a 90° angle is a "thing". Some degree of a bent knee is required to perform the various kicks, and varies from person to person.

But you do agree that in a 90° calves position, you use your ankles and your calves but not so much your thighs which are the most powerful parts of your legs, right? I am a lazy diver so I am a big fan of kick and glide. Not so much glide with the cave diver position and pretty much drag.

 

[ginti]

But you do agree that in a 90° calves position, you use your ankles and your calves but not so much your thighs which are the most powerful parts of your legs, right?

Not really.

The proper finning techniques are the ones shown in the video. If you maintain 90°deg at your knees at rest, you will just start each kick from that position, but the execution of the kicks shouldn't change.

In the second video posted by Ayisha (frog kick), Tracy has more or less 90°deg at rest. But he uses all the muscles of the legs when he kicks; the last part of the video shows the movement very clearly.

 

[mc42]

The standard sky diver / tech diver trim position with the slight back arch and bent knees can certainly cause some back tension and I can understand some concern with that. Some experience and core strengthening will help. Obviously if there’s a back condition you need to work around, being comfortable in the water and adapting is your main concern.

A few reasons why I think the knees bent position is good:

1. All my primary kicks are immediately accessible from this base position without needing to shift or adjust. From a modified frog I can back fin to stop, helicopter to turn slightly, modified flutter through a narrow spot, etc.

Most dives are low effort and I may just wiggle at my ankles to do a modified flutter kick. I often just use one fin for fun. Nothing else on your body needs to move.

If I need to fin fast of course the technique can change to a full-blown traditional flutter kick, or a fuller frog kick with a longer extension that lets the fin bottoms clap together due to the better ankle articulation.

2. Trim adjustment. I adjust my weighting so that I’m trimmed horizontally with bent knees. When I extend my legs, I can trim head up at various angles as needed. Now, I dive primarily dry suit, so it’s extremely important to be able to control my trim at all times, avoiding head down trim. When carrying extra cylinders or a camera, it is extremely helpful to compensate without having to exert by sculling with hands or feet, which can lead to bigger problems.

It sounds like you’ve adjusted your trim point so you’re horizontal with legs out which might limit your adjustment options. Whether it’s a perfect 90 degree knee bend I wouldn’t worry about compared to being comfortable and being able to control your trim. It’s all about building the biggest stable platform you can underwater.

3. More compact body volume. Bent knees might make it easier to turn or handle current because of reduced drag or weathervaning area and moment of inertia.

4. I’ve seen many frog kicking tech and rec divers stir up silt despite thinking they’re good at it but their buddies following them know better. You may want to video yourself close to a sandy bottom to see if you are indeed kicking anything up.

 

[Lorenzoid]

That's exactly that. I don't say that my thighs and calves are aligned as if it was made of one piece of wood. It is the 90 degrees that I find unnecessary, unnatural and inefficient if you want to move fast. But I agree it's sleek, pretty much tech diver style .

Then thanks for clarifying your original post. I think your question stemmed from seeing many pictures of divers in that idealized position of knees bent 90 degrees, which is good for some things but hardly needs to be maintained over a whole dive under most circumstances. It's apparently not necessary for the kind of diving you do. So okay, if you pause over a sensitive bottom to take a close look at something, lift your fins by angling your knees more. Other than that, who cares. As far as I'm concerned, that's the end of the story. Go out and have fun diving. Others may enjoy beating the proverbial horse at this point.

 

[Divin'Papaw]

Like you I am now a recreational only diver. I used to do some technical diving and used to DM a bit but now I'm just a recreational underwater tourist. With that said I dive pretty much in trim but without being anal about it. Depending upon the situation sometimes I'm heads down, sometimes heads up, sometimes perfectly vertical even (mid-water) ... but typically I'm in decent horizontal trim.

One thing I like to do is that when I'm diving in a sensitive area near the bottom I regularly look back to see if I'm leaving any type of a trail or stirring anything up. These days I like to do that at Blue Heron Bridge where there are silty areas. As long as I'm not stirring anything up as I move along than I know my trim and fin techniques are good enough. I also like to practice my helicopter turns and back kick at Blue Heron Bridge. I'd encourage you to have a benign site like this that you can use for practice and to regularly check your skill level.