What the heck?
THE "PERFECT ( being horizontal ) TRIM" HOAX
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What the heck?
I do not think that hand propulsion is OT, as the topic is here is trim. And with the ARO rebreather, most of the training was about using hands propulsion for controlling the trim (the buoyancy had to be controlled using the proper amount of oxygen in the counter-lung).
I try to answer to your question, about when hand-propulsion was removed from scuba training.
Here in Italy the ARO was the basic SCUBA system employed for training students to buoyancy and trim control (and breathing control, of course) during the first course. I think that hands propulsion disappeared when the ARO was abandoned, being replaced by an OC air tank plus a BCD.
This happened around 1982-83, as a reaction to the arrival (and success) of US-based training agencies such as PADI, NAUI, etc.
Suddenly it was possible to get a diving license in a couple of weeks, and without being a superman, instead of a 6-months-long training where only 20% of students were able to complete the course and get certified...
It must also be said that, whilst our previous training method was focused on buoyancy and trim and breathing control (as the ARO requires this), the "new" method did give very little importance to these aspects.
Students were simply told to "breath normally, never holding your breath", while before we had to train for months in the peculiar way of breathing required by the ARO. Most skills had to be performed by kneeling on the bottom, while previously with the ARO you had always to be perfectly neutrally buoyant. And the horizontal trim was impossible to keep with the horse-collar BCD units of the time, which did keep you vertical all the time...
I must admit that at the time, I was one of the instructors pushing for abandoning the ARO and the old training method.
40 years later, now I re-evaluate that old training method, which for certain parts was very good.
ginti
Contributor
And then students develop bad breathing habits and they do not understand why. This is my story - I needed to start tech training to better understand what I was doing wrong!
Anyway, sure what you said makes sense. It's just a pity that these techniques disappeared from the rec realm, because I do not see space for them in tec training (as explained a couple of posts above, hands are almost always busy)... so they will probably be forgotten
If we will ever have a chance to dive together, I'll have to remember to show me some techniques
Isn't the internet amazing?
I expect there is a difference between teaching hand propulsion techniques to a breaststroke champion, and to divers who barely passed the 5-minute float test and are constantly paddling forward doggy-style that probably creates more drag than propulsion. The latter will probably double their SAC if they simply stop doing that, and are the vast majority of the students.
lermontov
Contributor
do you still feel the same way today ? i use whatever method that causes the least amount of water stirring - virtually any fin movement stirs up fine silt, I often use a finger to push myself away from an object or to turn around instead of helicopter turns
His words are etched into my brain. It's funny how that works. I am almost terrified that if I move my hand, he will see me.
Similarly, he warned me early on that missing my turn pressure meant failing the class, with no refund. To this day, I can't imagine it is possible that any diver is more attuned to his turn pressure than I am.
I am also aware that he might read this post and pass judgment.
Jerome O'Neil
Contributor
Legs have bigger muscles and consequently, fins can be much bigger for your feet. Ergo, it is far more efficient.
Flailing is different from using your hands for propulsion. Most divers I have seen use sculling/flailing in order to keep their head up. They never got used to swimming like a fish and never learned small nuances like tilting their head to the right or left in order to look straight ahead. They dive with their head way higher than their feet and you'll notice that they scull/flail whenever they stop. Why? Because their heads up attitude (trim) in the water causes some downward thrust which pushes them up. They've accommodated for this with extra weight but once they stop kicking, they start to sink. Sculling can stop this and keeps their head up so they don't feel the falling. Unfortunately, flailing can really stir up silt if they're close enough to the bottom. They can add a bit of air to stop their fall, but then when they start to kick again, they will be too light and have to remove the air. Getting the right angle of the dangle allows all of your thrust to go behind you rather than some of it making you lighter. There's no doubt in my mind that the first step in gaining control is to get horizontal and break your habit of sculling. We call them rototillers because their feet are in constant motion and they are often leaving all of us in a cloud of silt. Many of them are white knuckle divers because they don't have real control.
I've taught a few paraplegics and am an instructor with DiveHeart. Early on, I did a "try dive" in a pool with a gentleman who had lost his legs in a motorcycle accident. He was pissed with the world as he got in and I watched a lot of that angst evaporate with his newfound freedom. It was nigh on magical. Up until this point I had dove with a number of quads, site impaired and autistic divers, so this was close to being a first for me. At the end of the session, he asked me what a particular sign was and demonstrated it by holding his hands together. Whoops. I explained that was how I dived and realized that I need to dive like my students from there on out. There is a right way to use your hands and it does not resemble sculling/flailing at all. If I'm diving with a paraplegic now, I only use my hands except in an emergency. Needless to say, I am exhausted at the end of such a dive and my air consumption drops dramatically. But, students learn more by mimicking their instructor, so I'm committed to diving it their way when needed.
Just as a point of physics, if that were the case, they'd be swimming backwards.
I wouldn't be surprised -- but to test this hypothesis we'd have to tie their legs and take away their fins. They might object.
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