Is scuba gear life support?

[Waterwulf]

I got my first qualification here in America in the early seventies. It was a NAUI course and was taught on a Special Operations base by SpecOps soldiers working part time for extra money. They taught us the way they had been taught and although I thought it was at times brutal, there were some girls in the class who were doing it all too with no complaining so there was no way I was going to wimp out.

Our final open water test included a free ascent from sixty feet. It was actually easy after all of the drills and simulated emergencies we went thru. However, I want to point out a few things that we were taught then and I have learned since. It was taught to us back then that the free ascent that we were required to do, was not to practice free ascents. It was to show us that we could do it. Since we were all supposed to know from harder breathing (and maybe a pressure gauge!) that we were getting low on air, a free ascent would most likely be because of a catastrophic failure of our gear. That meant that you might not have full or even half full lungs when it all goes bad.

Back then, most of us had converted life jackets that we stole from the Air Force or Coasties to use as BC's, a single regulator with no octo, no pony bottle, maybe a pressure gauge, no SMB's, no etc. SCUBA diving was still fairly new and lots of companies started making gear and then folded. There was some crappy stuff on the market and some flat out dangerous stuff. People died because gear failed. Training was tough to keep us alive long enough to learn on our own.

That was back then. Nowadays, gear is much more reliable, safety systems are in place, etc. It's a much safer sport. I think that some training leaves a lot to be desired but requiring training and planning for a free ascent is overkill.

 

[CG43]

If rec scuba diving were limited to navy seals, young and fit athletes, and experienced free divers who could safely CESA from any depth, there wouldn't be any scuba industry to speak of.

We all consider redundancy in scuba diving to be important.
I don't think anyone here seriously doubts that this can be a technical system like a pony bottle.
Seriously, no one here wants to destroy the scuba industry.
The question is within what limits freediving can be this redundance , and if so, to what extent one should it be practiced and tested .
A CESA should never happen, but what turns an OOA situation into a CESA? Why does the heart rate have to go up and stress set in? There is absolutely no compelling reason for this, as not breathing underwater is normal for a freediver.
And this is not just theory but experience, also my own during my very first scuba dive ever.
I was a 16-year-old freediving boy and was supposed to search for a heavy homemade waterski in an artificial lake. The owner said he was a diver himself but now only had a tank without a J valve and a regulator without a SPG. He didn't know how much pressure was in the tank, probably little. The lake is 20 meters deep, visibility at the bottom is zero. He would first fill the tank and advised against the dive. I said I could dive 20 meters even without scuba, but then I wouldn’t be able to do a meaningful search with such a short bottom time, and if I found the heavy ski I would be hindered during ascent. I told him, 'Give me your scuba gear, and if I run out of air I’ll come up, that’s no problem.'
I didn't found the ski, emptied the tank in just 17 meters, and slowly surfaced again while exhaling.
That wasn't a CESA but simply a controlled ascent , but fear could have turned it into a CESA .

Since we were all supposed to know from harder breathing (and maybe a pressure gauge!) that we were getting low on air, a free ascent would most likely be because of a catastrophic failure of our gear. That meant that you might not have full or even half full lungs when it all goes bad.

The regulator I used on my first scuba dive had an upstream second stage. In these stages, the cracking pressure decreases when the intermediate pressure (IP) drops. This inevitably happens when the tank pressure falls below the usual IP, that is, shortly before the tank is empty.
As long as you only breathe slowly at shallow depth, you can be surprised by an empty tank. On the other hand, if you know this effect and notice that the cracking pressure of an upstream stage decreases, you know that the tank is almost empty.
At my first cubadive I was totally surprised by the end. Breathing was so wonderfully easy, even it was the cheapest reg. I had just started to inhale when suddenly there was no more air. The owner had said that there is probably not much air in the tank, so it was probably empty but it could also be a failure of the scuba. As I slowly swam up I calculated: empty or failure? At a depth of about 8 m I have the solution. The tank went empty in 17 m = 2.7 bar pressure. Now in 8 m = 1.8 bar it must be possible again to breathe out of the tank, which was also possible. But I breathed very little because there should always be more pressure in the tank than the ambient pressure. On the surface, I then told the owner 'tank empty'.

 

[Waterwulf]

We all consider redundancy in scuba diving to be important.
I don't think anyone here seriously doubts that this can be a technical system like a pony bottle.
Seriously, no one here wants to destroy the scuba industry.
The question is within what limits freediving can be this redundance , and if so, to what extent one should it be practiced and tested .
A CESA should never happen, but what turns an OOA situation into a CESA? Why does the heart rate have to go up and stress set in? There is absolutely no compelling reason for this, as not breathing underwater is normal for a freediver.
And this is not just theory but experience, also my own during my very first scuba dive ever.
I was a 16-year-old freediving boy and was supposed to search for a heavy homemade waterski in an artificial lake. The owner said he was a diver himself but now only had a tank without a J valve and a regulator without a SPG. He didn't know how much pressure was in the tank, probably little. The lake is 20 meters deep, visibility at the bottom is zero. He would first fill the tank and advised against the dive. I said I could dive 20 meters even without scuba, but then I wouldn’t be able to do a meaningful search with such a short bottom time, and if I found the heavy ski I would be hindered during ascent. I told him, 'Give me your scuba gear, and if I run out of air I’ll come up, that’s no problem.'
I didn't found the ski, emptied the tank in just 17 meters, and slowly surfaced again while exhaling.
That wasn't a CESA but simply a controlled ascent , but fear could have turned it into a CESA .


The regulator I used on my first scuba dive had an upstream second stage. In these stages, the cracking pressure decreases when the intermediate pressure (IP) drops. This inevitably happens when the tank pressure falls below the usual IP, that is, shortly before the tank is empty.
As long as you only breathe slowly at shallow depth, you can be surprised by an empty tank. On the other hand, if you know this effect and notice that the cracking pressure of an upstream stage decreases, you know that the tank is almost empty.
At my first cubadive I was totally surprised by the end. Breathing was so wonderfully easy, even it was the cheapest reg. I had just started to inhale when suddenly there was no more air. The owner had said that there is probably not much air in the tank, so it was probably empty but it could also be a failure of the scuba. As I slowly swam up I calculated: empty or failure? At a depth of about 8 m I have the solution. The tank went empty in 17 m = 2.7 bar pressure. Now in 8 m = 1.8 bar it must be possible again to breathe out of the tank, which was also possible. But I breathed very little because there should always be more pressure in the tank than the ambient pressure. On the surface, I then told the owner 'tank empty'.

Back then, everybody used J valves. They'd give plenty of warning with enough air left over to get you to the surface. I still use them on my tanks nowadays.

 

[lizardland]

We all consider redundancy in scuba diving to be important.
I don't think anyone here seriously doubts that this can be a technical system like a pony bottle.

It's not that complicated. Your pony bottle is already swimming alongside you. To get to a CESA then you've managed to lose your partner and either run out of gas or have a catastrophic failure that causes you to lose all your gas. And to be honest, running out of gas is the far more likely scenario than a catastrophic failure. These are avoidable combinations of events.

Personally I don't even bother training for CESAs any more. I've not done one since I stopped teaching about 18 years ago. It's not something that is even in my thought processes. I could probably do one if I had to but it does not even enter into my planning.

Monitor your SPG, monitor your buddy. Where that becomes impractical, redundant air sources.

 

[The Chairman]

They'd give plenty of warning with enough air left over to get you to the surface.

Almost always. I've bumped the valve to "open" twice. Hilarity ensued.

 

[The Chairman]

Historically, the concept of treating your Scuba gear as "Life Support" was advanced to scare us into servicing our regs ONLY at a Scuba shop. Meh. After I was overcharged by a shop for servicing a reg, and having it fail on the first dive, I stopped trusting them. I learned how to service my own gear and have not had a failure since. It's probably not for everyone, but it's simple enough that most anyone can do it.

 

[Bogie]

Common sense.
If it is supporting your life it is life support.

 

[Waterwulf]

Almost always. I've bumped the valve to "open" twice. Hilarity ensued.

Yeah, I can understand that. That was one of the things the instructors harped on us about. You had to check that J Valve every few minutes or you got dinged. We got screamed at over it. "Listen up turd heads. Your J valve gets bumped to on. It happens and is no big deal. Not checking it at least once in five minutes is a big deal. Here in class, I'll fail you for it. Out there, you'll die if you screw it up". It became so ingrained that for six months, all of us students walked around waving our left hands behind our butt cheeks looking for the handle. To the "Surface Dwellers" it looked like were all waving away stinkers. I still use J valves to this day.

 

[happy-diver]

Yes not diving for some is life support

 

[Subcooled]

No, it's sport equipment.

Some people think that life support equipment is used when your body fails
Some people think that life support equipment is used when your body is OK but the environment is not

Now, choose.