Folded Knees

[rongoodman]

can anyone comment on the differences in finning technique? When you dive with knees bent and doing the "modified flutter kick" you essentially want your thighs to remain in-line with your torso, and extend your shins away and toward your body with a loose ankle? And for frog kick, again your knees keep the fixed bent pose?

Pretty much. You might end up with even your shins remaining fairly quiet and just your ankles driving even smaller kicks, though, depending on the circumstances.

 

[boulderjohn]

A lot of the special kicks that require the bent knee pose (modified flutter, modified frog, back kick, helicopter turn) are designed for maneuvering through tight spaces. If you aren't maneuvering through tight spaces, they aren't needed.

 

[Dody]

I can't see how you would do a back kick or helicopter turn with straight legs, and I've watched far too many divers kicking up sand and silt with straight legged flutter kicks from several feet above the bottom, completely unaware of what they're doing. Divers modified the various kicks to work with bent knees in order to provide more control and avoid disturbing the bottom and those are useful things to practice, no matter what the type of dive. It's just that they become more critical in an overhead environment.

Of course when I back kick or do helicoper kick, I bend my knees but in the horizontal plan. I don't have my calves directed up. I will not do flutter kick if I am close to the sand or silt. Frog kick will do with no stirring.

 

[Dody]

Thank to whoever corrected my typo in the title

 

[Lorenzoid]

Of course when I back kick or do helicoper kick, I bend my knees but in the horizontal plan. I don't have my calves directed up. I will not do flutter kick if I am close to the sand or silt. Frog kick will do with no stirring.

If your frog kick doesn't end with the fin tips drooping to the sand or silt as you say they don't, then perhaps you are keeping your knees slightly bent (i.e., calves angled above horizontal) without thinking about it? It's difficult to end a frog kick with your body as straight as an arrow from your torso to your fin tips because of the weight of the fins; when you extend your legs into the "glide phase" at the end of your frog kick, the fin tips want to droop to some extent as your glide slows ... unless you are counteracting that by bending your knees somewhat.

Also, in the glide phase of the frog kick, you have just clapped your fin bottoms together; I don't even think it's anatomically possible to do that without your knees being bent.

By the way, when you refer to the "folded knees" you may be visualizing the knees at 90 degrees. A full 90 degrees isn't really necessary; a lesser angle can often provide the benefits people have mentioned (and can be more comfortable).*

* Note my avatar. Knees are 90 degrees there--probably because I'm trying to float motionless while looking at the photographer--but it really isn't all that useful to maintain 90 degrees throughout a dive.

 

[tursiops]

Some weeks ago, I woke up with a terrible back pain. I never had a back pain before and I am 52. The following night, the pain was so acute that I could not sleep. The next day, I went to see a doctor (in my previous dives, I had been very very far away from risking DCS or any other diving related disease. No deco, not even close to NDL, no rapid ascent, full respect of safet stops,…) who directed me to a physiotherapist. The first session really reduced my back pain and the therapist advised 3 sessions a week for a month. It’s been three weeks now. Just to play safe, I haven’t dived in the ocean since and just practised some exercises in the pool, fully geared. I fixed a submarine camera to film myself and my findings are: what the hell? All the experts and all the videos show divers with their knees folded. I understand that it is a must for tech divers but what about recreational? As a rec diver, my trim is better with my entire body on a straight line, my fins, calfs, thighs, aligned. I am more efficient streamlined doing flutter, frog kick rather folding my knees. And frog kick does not disturb the silt. I even do reverse without folding my knees. What is the point of folding knees as a rec diver?

I am skeptical that it is possible to do a frog kick with straight legs.

 

[Dody]

By the way, when you refer to the "folded knees" you may be visualizing the knees at 90 degrees. A full 90 degrees isn't really necessary; a lesser angle can often provide the benefits people have mentioned (and can be more comfortable).

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 .

 

[Raphus]

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 .

True, but divers normally don't want to move fast.
We want to have control. And be able to stop anytime and be still in (whatever type of) trim and buoyancy.
bending the legs makes this possible.
It's relaxing and gives huge control about the positioning.
But it takes some dives to get used to it.

 

[boulderjohn]

I thought I would relate a story that is indicative of the difference between typical recreational diving attitudes in the water and typical recreational diving attitudes on ScubaBoard.

I was on a recreational dive boat in South Florida. One of the other divers had requested a DM, so the boat had a DM in the water, which was not the usual case. We were doing a basic reef dive, and I was primarily just drifting along over the reef in the light current, with only occasional kicking. Back on the boat, the DM came over to give me some helpful tips. He had noticed my posture while diving and offered to help me get my feet down. One of his suggestions was ankle weights. I thanked him and told him I was happy diving as I was.

 

[Raphus]

I thought I would relate a story that is indicative of the difference between typical recreational diving attitudes in the water and typical recreational diving attitudes on ScubaBoard.

I was on a recreational dive boat in South Florida. One of the other divers had requested a DM, so the boat had a DM in the water, which was not the usual case. We were doing a basic reef dive, and I was primarily just drifting along over the reef in the light current, with only occasional kicking. Back on the boat, the DM came over to give me some helpful tips. He had noticed my posture while diving and offered to help me get my feet down. One of his suggestions was ankle weights. I thanked him and told him I was happy diving as I was.

Same happened to me..
An old Instructor told be my feet were to light and would stick up. He also recommended ankle weigths...

Ofc there is no right and wrong.
Some techniques are clearly better,but not every diver needs to know them.