Problems keeping knees bent.

[rakpix]

I've been working on getting my trim just right for the last few weeks. My buoyancy control is good, and I'm comfortable in the water. But one thing I (apparantly) need to work on is keeping my knees bent, to put my calves perpendicular to my body, and my fins parallel to my body. My buddy observed me dropping my legs down so everything: body, thighs, calves, fins formed one straight line. And I'm doing this unconsciously! Every time I focus on over-bending my legs, it feels really unnatural and my kick loses all efficiency. How can I improve this? Thanks.

 

[Deefstes]

Good question, I'll be checking this thread for answers as I seem to have the same problem.

 

[MauiScubaSteve]

In a wet suit the only reason to "fin" with calves perpendicular to your body and fins parallel to your body is to avoid silting a mucky bottom. As it is a specialty finning technique, speed and power are sacrificed to NOT disturb the bottom.

It seems to me that for the majority of dives every day, being mostly warm, clear, tropical (wet) proper trim is described as the entire body straight horizontal. I actually teach my paddle fin OW students (+90%) NOT to bend their knees (the water bends your knees, not your brain).

I am not really a fan of horizontal. I prefer head slightly lower than fins, with a straight or slightly arched back. Fin thrust is still away from the bottom, but you get ALL the fin thrust.

More profile info would help get your answer.

 

[vladimir]

Well, people will tell you to practice until it feels natural, and that's probably good advice. I tend to relax into, say, a 120º angle between body and calf and a 120º between calf and fin. My fins are still parallel to my body, but I'm spread out a little, and don't have to arch my back as much to maintain the position. I'd guess this is not the recommended technique, but I don't have anybody to impress while I dive, and it keeps me in good trim and keeps my fins off the environment.

 

[Walter]

As halemanō says your legs should be fairly straight when using a flutter kick.

 

[Guba]

Whew! For a few moments there, I thought I was doing it all wrong. I normally tend to keep my legs fairly straight when finning along, a habit acquired from teaching swimming, I guess. I modify my kick only when attempting to avoid silting, and that, as noted by others, usually sacrifices speed and efficiency in the name of preserving visibility (and the good graces of fellow divers).

 

[Jeff Toorish]

If you feel your legs sinking --there are two potential issues, weighting and trim.

Weighting: try moving your weights higher on your waist. If you are using integrated weights, try switching to a weight belt.

The other problem may be trim, try moving a few pounds higher on our body, around your shoulders. Sometimes just an ankle weight around the tank valve will do the trick.

Jeff

 

[TSandM]

Assuming that you want to achieve the cave diver's posture (which actually works fine in open water diving -- why DO people want to swim fast, anyway?) then the first question you need answered by your buddy is whether your entire body is rotating so that your feet are low, or whether you are "breaking" at the hips. If the latter, some practice prone on a floor, raising your knees off the carpet and memorizing which muscles you used to do that, may be useful.

If the former, it may be necessary to move some weights. HOWEVER, if you are using negative fins, like Jets, then bending your knees alone may be enough to stop the rotation, as it shortens the lever arm that the negative fins have to work with. I'm not sure why the bent knee position disturbs your kick, although the technique for kicking in that position IS different. When you flutter kick, you do the kick from the knees, not from the hips -- the knees stay together and just extend and flex. It's still a powerful kick, just different.

 

[MauiScubaSteve]

Well now that the work "fast" has been typed, IMO speed, power and efficiency are not always the path to "fast."

A few days ago I did an OW training dive with a pretty fit, pretty good in the water, 40ish male student; his certified gf and my bdb beanniebrew tagged along (both in original SP split fins btw). The pace is set by the slowest diver and beanniebrew pokes along in rear DM/critter finder position so I know I'm not swimming "fast." Even so, after the hour long dive where he and I did compass skills "3 times" he did say that he felt like his "kick cycle" in cheap full foot snorkel rental fins was 2-3 for each of my "kick cycles" with my free dive fins.

On our way out across the sand bottom of Kapalua Bay I pointed out his rototiller sand cloud/trail (snorkeler body position). By the end of the dive coming back in he was not rototilling (formula 1 body position) and he was easily keeping up with the pace of the split fin girls. We went the same distances but who did the most work? Why work harder if you don't halve to? A primary goal in my OW class is for each diver to use the least amount of energy to accomplish what ever we accomplish (specific to their own gear and physiology).

If the OP is bottom diving a landlocked lake or quarry, dry, the cave diver posture seems a top contender.

 

[TSandM]

Well, I don't know what you were doing with this student, but having dived with you, I will tell you that, by MY standards, you swim fast!