I finally get it: paddles vs splits.

[elmer fudd]

My Facebook profile pic,

 

[lavachickie]

That's weird. I can back kick and do a helicopter turn or one-legged turn in my Tusa X-pert Zooms.
It is easier to do those kicks in a paddle fin, though.

To be completely accurate, it could be done; but the resulting power was about... 1/10... what I've found I could generate with paddles after using them for just four dives over a 24 hour period.

 

[lavachickie]

lavachickie, why do you want to do a flat-out swim?

When I did my DM test, I just switched to better fins for swimming forward fast. In ALL my other diving, I can swim fast enough in my Jets. It's not real fast, but since I avoid swimming against strong current and like to watch critters, it's fast enough.

Cuz I might need to. I don't plan of course going all out, but I do need to juice up some muscles so that if I need to for a short period, I can. I will certainly be doing the DM test swims in splits, and I'd take splits for any easy going warm water diving.

 

[elmer fudd]

Cuz I might need to. I don't plan of course going all out, but I do need to juice up some muscles so that if I need to for a short period, I can. I will certainly be doing the DM test swims in splits, and I'd take splits for any easy going warm water diving.

I like being able to swim fast myself. I may not need to, but sometimes it's just more fun to put on a burst of speed and chase crabs or fish around a bit. As I really prefer to dive wet, I also find it helps keep me warm. Splits don't do it for me, but someday I'm going to pick up some Cressi Garas or something similar.

 

[beanojones]

It dawned on me some time ago that fins really aren't very ergonomic. Both flutter and frog kicks really don't make efficient use of our muscles.

A walking, bicycling or stair stepping motion would be far more ideal and really allow us to use our muscle groups. There's no practical way that I can think of to make that kind of movement generate propulsive force though.

Anything that would make use of our muscle groups (other than a dolphin kick) would also create hydrodynamic issues. If you think about just how thin air is, and yet aerodynamics has such an effect on gas mileage, then you can imagine just how much more effect water has. (weight of a cubic foot of water= 62 pounds. Weight of a cubic foot of air= 0.0807 lbs..)

Ideal motion is like a fish (dolphin kick) using the large muscle masses in our back and stomach, as well as our legs. Thus free divers set records on a single breathe with one large single fin, propelled by whole body motion.

The frog kick is efficient precisely because of the glide which occurs in the maximum hydrodynamic pose, not because it is otherwise particular efficient.

 

[elmer fudd]

The dolphin kick doesn't seem to work so well for scuba though. I sometimes use it, but it just doesn't give anywhere near the acceleration that you get without the tanks.

 

[highdesert]

Isn't that what cause people to do the bicycle pedal style of finning? They just kick in the most natural movement they are use to.

I don't think that's the case at all. I'm on my bike for 30 miles most days, hard and fast. It's a great conditioner for diving, both in the cardio aspect and conditioning leg muscles. The two environments are so dissimilar that there is no carryover of bicycling into finning. To the contrary , the increase in leg and glute strength allow for a very easy, efficient finning motion.

 

[beanojones]

The dolphin kick doesn't seem to work so well for scuba though. I sometimes use it, but it just doesn't give anywhere near the acceleration that you get without the tanks.

That's because tanks increase your mass significantly, and decrease your hydrodynamic efficiency tremendously. It is not because the kick gets less efficient. It is still be the most efficient kick if speed is all that matters, because it is the only continuous kick which does not present actual hydrodynamic barriers to forward movement. Such barriers presented by the frog kick does on the spread part of the stroke (unless the spread is done when stationary), or a flutter does on any part of the kick except when the fins are passing each other.

On scuba though, we usually are more concerned with other things than speed. When I am trying to corral a ray to show cutomers though, nothing mores me faster than an all out dolphin. Max speed, however even with the very efficient dolphin kick tends to absolutely eat air because with scuba we present a remarkably inefficient profile no matter how perfect our trim is. This is why some people are still in love with the Cousteau triple tank system which was much, much more hydrodynamic. People who have them rave about their speed in the water. I cannot dive it with customers, but when I used it, I felt much more like I was free-diving, slipping through the water, rather than pushing a bunch of water.

Tech gear has just made things worse then ever for hydrodynamic efficiency, what with the doubles, and the extra weight of double regs and valve, and the essentially doubled hydrodynamic profile.

EDIT: The only picture I can find of the triple tanks is this:
http://www.divingmachines.com/vintagescuba.html

Look for the UDS-1. That's not quite the one I dove, but it is like that. Small triples enclosed in a hydrodynamic shell. Smaller diameter tanks are more than proportionally lighter, and wrapping them in a shell makes the smaller profile much more efficient.

 

[DazedAndConfuzed]

I don't think that's the case at all. I'm on my bike for 30 miles most days, hard and fast. It's a great conditioner for diving, both in the cardio aspect and conditioning leg muscles. The two environments are so dissimilar that there is no carryover of bicycling into finning. To the contrary , the increase in leg and glute strength allow for a very easy, efficient finning motion.

If a person has never bicycled before, would a beginner doing the circular kick motion think is natural? As opposed to someone who is used to that bicycle motion and started diving, they might automatically go into the bicycle motion because it is easier on their legs and also because they will instinctively do that.

 

[elmer fudd]

Look for the UDS-1. That's not quite the one I dove, but it is like that. Small triples enclosed in a hydrodynamic shell. Smaller diameter tanks are more than proportionally lighter, and wrapping them in a shell makes the smaller profile much more efficient.

I knew exactly which rig you were talking about before I even clicked on the link. I love the old vintage gear. I dove my RAM last weekend and I'm thinking I might take out a Healthways this weekend.

Unfortunately, I've never tried out the UDS system. No real plans to either, despite the fact that it does look very streamlined. As I understand it, they used 6351 aluminum tanks with oddball neck threads, which means I'd have a lot of difficulty getting them filled and I couldn't just replace the old tanks with some new ones.