Is it OK to turn off O2 in Rebreather Training?

[Superlyte27]

What is the point of this comment? We are talking about training OC divers to be CCR divers. To take your comment at face value, we should just have an initial pass/fail test.. you sound as if solid po2 monitoring is. Pre-req to sign on for CCR training. How could you possible have this drilled into your head with only a background in OC diving?

So my standards say you should be looking at your HUD at least once per minute and verifying it with a handset about once every 4 or 5 minutes.

Any idea how long it takes for ppo2 to drop from 1.2 to .8 at constant depth, no work and no flow? A LONG FRIGGIN TIME

Also keep in mind that the second PPO2 drops to 1.1, the solenoid starts clicking like crazy. And you still don't notice!?!? It's not quiet.

If they miss this, they fail that dive. If they miss this consistently, they are NOT passing the class. I can't count on them to live and I can't be there to babysit them after they leave class.

 

[doctormike]

Your implication that a submariners training under heightened awareness somehow makes them unable to respond to real world emergencies is a little ignorant and short sighted to say the least.

Come on, you know that I didn't say that.

You can't keep people constantly in a "heightened state of awareness", otherwise that just becomes your baseline state of functioning. That's what "heightened" means.

The idea of the stealth O2 shutoff drill is that it EXACTLY simulates what happens in real world conditions, when you aren't expecting the instructor to throw a drill at you.

If you actually care about this discussion, and don't just want to throw around a straw man argument, take a look at this post. It describes my point pretty well.

 

[Superlyte27]

The submarine scenario is about muscle memory and repetition. We do this with a stupid amount of boom drills. The oxygen shut off is about complacency and critical thinking skills and problem solving.

I'm not giving someone any help in ruling out complacency. They either get it or they don't. This isn't 3rd grade where everyone gets a trophy. There are no hints or bonus rounds. This is life and death.

As a student, you're either bright enough to overcome this or you stick to OC. Or perhaps you find another instructor that is easier to pass. Is that in YOUR best interest? Is it in the best interest of your family to take the easy way into tech diving? If so, I promise, I'm not the instructor for you.

 

[hroark2112]

As a former submariner, I can remember times when the CO or engineer would walk back to the engineering spaces and flip off the control rod breakers, shutting off the reactor. No warning at all, nothing. It sucked, but it always got handled. Sometimes we got an ass-chewing for not doing it perfectly, but it was always a good learning experience. The same went for fire drills, flooding drills, and any other kind of drill they felt like throwing at us. Yes, knowing we had drills coming put us in a heightened state, expecting something to happen at any time, but the reactions were exactly the same for expected drills and unexpected drills.

That being said, I'll never turn off someone's O2 without them knowing about it. I think there are ways to teach the skill and get the muscle memory started without actually flipping the valve. That's just my opinion. I've had some damn good CCR instructors and none of them touched my valves either.

I'm not going to toss poo at any instructor who does, provided it doesn't violate standards, we all believe differently. I was initially certified (open circtuit) in the days when instructors would turn off your air with no warning, and I hated it. Yes, I know it's totally different and I well know how long it takes to drop your PO2 from 1.2 to .5 at 60'. I am a big believer that there is a point where the risks of an exercise outweigh the training value. I've been neck deep in water in a flooding trainer, with more and more leaks popping up left and right, and in that very controlled environment it was excellent training. Doing the same thing to an operating submarine would be insanity, even if you think you know you can recover from it. Yes that's an extreme example, but it's not really all that different.

Just my opinion here, YMMV.

 

[Superlyte27]

l know how long it takes to drop your PO2 from 1.2 to .5 at 60'.

Just my opinion here, YMMV.

I'm curious, hroark, do you know how fast it will drop if I do the skill at 120'?

 

[doctormike]

That being said, I'll never turn off someone's O2 without them knowing about it. I think there are ways to teach the skill and get the muscle memory started without actually flipping the valve. That's just my opinion.

I'm interested in other people's opinions. I hope that you understand what I'm saying.

If you are considering "the skill" to be how to open your O2 valve, then yes, you don't need to shut off a student's O2 to teach them that skill.

But this teaching method has nothing to do with muscle memory. Muscle memory is for things like opening your O2 valve, deploying a long hose, loop recovery, shutting down an OC manifold, etc...

This teaching method is about having the student realize something is happening in real time and think it through. That's not a muscle memory task.

Once again, please read my post on this to see the difference between a failure that is prebriefed and not prebriefed.

And realize that while there is some risk in any type of training, the danger for this drill depends on (1) the student not noticing the dropping PO2, (2) the instructor dying or becoming incapacitated, and (3) the student not noticing the eventual hypoxia alarms.

 

[hroark2112]

I’ll use round numbers because I’m lazy.

66’ is 3 atmospheres. 132’ is 5. So probably about 40% longer.

Unless, of course, some of the variables change. Breathing harder, colder, stressed out, then less than 40% longer.

I’m not slamming anyone for teaching that way. There are lots of ways to skin a cat. Just none that the cat will enjoy.

 

[hroark2112]

doctormike, I understand what you’re saying completely. I’ve been part of many different kinds of training, some of it a whole lot of of fun like laying on the tarmac at JFK airport as a crash ‘victim’ to countless drills on submarines to more than one actual incident where direct actions had to be taken to save lives.

I still don’t plan to shut anyone’s O2 off anytime soon.

 

[doctormike]

doctormike, I understand what you’re saying completely. I’ve been part of many different kinds of training, some of it a whole lot of of fun like laying on the tarmac at JFK airport as a crash ‘victim’ to countless drills on submarines to more than one actual incident where direct actions had to be taken to save lives.

I still don’t plan to shut anyone’s O2 off anytime soon.

Fair enough! I think that most folks in this thread agree with you...

 

[Superlyte27]

I’ll use round numbers because I’m lazy.

66’ is 3 atmospheres. 132’ is 5. So probably about 40% longer.

Unless, of course, some of the variables change. Breathing harder, colder, stressed out, then less than 40% longer.

I’m not slamming anyone for teaching that way. There are lots of ways to skin a cat. Just none that the cat will enjoy.

Bwuahahahaha, It was a trap.
Ask for your money back from the very good CCR instructors.