Why no hands?

[mcpowell]

I had an interesting discussion with my son about this, so I'm interested in seeing what you think. I admit, I don't like seeing divers flailing along with poor finning technique, or overusing their hands. But my son had some interesting points:

1) Fish, dolphins, turtles, etc all have front fins and use them.
2) Small hand movements use small muscles and very little energy.

So if your hands are not otherwise engaged with gear, why not use them?

I told him it was because it made him look like a dork.

 

[JohnnyC]

Fish, dolphins, etc. have evolved to be efficient swimmers, we have not. Those small movements are used in conjunction with their forward movement as control surfaces (for the most part. No frogfish here....). Think of them like elevators or ailerons on an aircraft. They are control surfaces.

Conversely, look at turtles. They use a significant amount of forward fin movement to propel themselves. They use comparatively little rear fin movement. That is much more akin to how a human uses its arms and hands in the water. It is not a small movement, and is not the same small hydrodynamic stroke designed for control, it's designed for propulsion.

We don't need to use our hands under the water because we have our fins for propulsion. However they can't propel us fast enough for small hand movements to steer ourselves underwater. Either our hands would have to be massive, or we'd have to move A LOT faster in the water to make the small control surfaces functional. Hand and arm movements that DO provide enough propulsion to physically move us in the water, are neither small, nor efficient.

 

[tbone1004]

they are incredibly inefficient

Fish, dolphins/whales, seals, etc have pectoral fins that are control surfaces vs being used for propulsion. Seals being the slight exception since their rear flippers are separate but when in the water they act as a singular propulsion device.
Turtles and Sea Lions do the opposite with their propulsion being generated in the front and their back end acting as a control surface, but since their front end is independent they can do a lot of their motion by differential forces with each "arm"

When we are moving in the water, the fins are infinitely larger than our hands and make a much more efficient method of propulsion whether that is forward, backwards, or turning *though some may argue that backwards is easier with your hands*. If we are on a scooter however and being towed, then our fins act like the control surfaces on a plane or the various aquatic mammals mentioned above. Since we move incredibly slowly in the water, using our hands as control surfaces to change things like pitch or roll like a fish would is pretty useless, and since our fins are independent, we can get all of the motion we need from our feet.

Add all of that up to the fact that your hands need to be prepared to "do" things independently of controlling your motion, so you need to have complete control with your feed.

 

[Lorenzoid]

Also, maybe it's not a good idea to allow ourselves to make it a habit--that is, routinely use our hands to propel ourselves such that it becomes ingrained in muscle memory. If using hands becomes an ingrained habit, it might inhibit us from keeping our hands always available and at the ready for emergency situations. Carrying a camera raises similar issues, but at least one could drop the camera and handle the out-of-air situation or whatever the situation may be and not have to think about propulsion.

 

[tursiops]

(1) Fish, dolphins, turtles, etc do not have the ability to use their rear propulsion units the way we can; we can do helicopter turns, back kicks, change from frog to flutter....and we can't kick the way *they* do. Much of their front-fin use is for steering, not propulsion. We can use our fins to steer. those animals that actually use their front fins for propulsion have large front fins....like turtles.
(2) Small hand movements use small muscles and very little energy, and thus provide very little help. Large hand movements can do something, but at the expense of large energy.

My particular dislike is someone who edges carefully up to something small to look at it, then furiously waves his/her hands to back up and get away...thus providing a turbulent (sand)storm to the little thing that was being examined. Number 2 dislike is the person tries to swim away and swims over the little thing, and kicks the crap out it. Learn the back kick to avoid this.....

It is also possible to take a dump underwater, and fish do this too.

 

[johndiver999]

There is no problem with using your hands to spin or to make small adjustments. The problem is that a lot of divers are going to want to occupy their hands with a camera, a light, a tool, spear etc. plus hand swimming tends to scare fish and if the diver is really using their hands for propulsion, they tend to catch a buddy’s regulator hose and rip it from their mouth- when swimming closely or in bad vis. Giving the kid something to hold and carry is a good training aid

 

[Snoweman]

Do a nice breast stroke, and you might rip your buddies reg out of his mouth.

 

[Esprise Me]

I think the main reason our hands and arms are inefficient is that we don't put fins on them. Swimmers without fins use arms and legs, and serious swimmers develop muscular shoulders and backs from all the work their arms do. We could put fins on our hands, but we need our hands for other things, and besides, our legs are bigger and stronger so we don't have to build them up as much. One thing our legs lack is the kind of precise movement control our arms have developed. Most people can instinctively flail their arms to right themselves when they're listing to one side, or drifting in a direction they don't want to go, but it takes practice to learn to back kick and do helicopter turns with your legs.

 

[ofg-1]

.It is also possible to take a dump underwater, and fish do this too.

There is no fish anywhere that has to take off a bail out bottle, harness, weight belt, unzip a wet suit jacket and pull down a farmer john to take a dump, and then put everything back on, or so I've heard. Give humans some credit.

 

[gr8jab]

Is it also that hand-swimming is usually a sign of poor buoyancy control? I see lots of divers who constantly swish their hands back and forth, maybe to add a little upward thrust to counteract their negative buoyancy. If they stop this constant flapping, they sink...