Is it worth practising OOA?

[Deefstes]

So I've been wondering about this one. I do try to manage my gas properly so that I will never run the risk of going OOA and so far I have never. But is it perhaps worth simulating an OOA experience by diving on a nearly empty cylinder but making sure you take the necessary safety precautions (buddy for one)?

Thing is, I have no idea how my regulator would perform when the air supply is about to stop so I don't even know what the warning signs are. Also, while I'd like to believe that I will keep a cool head, I can't be sure how I would respond if I do go OOA.

So, do any of you have specific opinions on this one way or the other?

 

[DevonDiver]

If you want a skill to work, you need to practice it.

Personally, I'd want to be able to donate or receive air, without undue stress or risk of failure, should the event ever occur.

It's an insurance policy. Better to have the skill and not need it, than need it and not have it.

When judging risk, it's important to consider both probability and consequence

Low probability + Low consequence = Low priority.

High probability + Low consequence = Moderate priority.

Low probability + High consequence = High priority.

High probability + High consequence = Very high priority.

Actually, I wouldn't rate air-sharing as a low probability - but that depends on who you have the privilege or misfortune to dive with...

 

[boulderjohn]

I think you should practice the donating part of it regularly, especially if you have a buddy you dive with frequently. Many tech divers do some degree of such practice at the beginning of every dive.

On the other hand, I don't think you need to practice it by actually running out of air on a near empty tank. I think the skills will transfer properly in a real situation.

As far as what it will feel like when you are running OOA, it is hard to predict. It depends upon the quality of your regulator and your depth. You might have no warning at all, or you might have several breaths in which it is hard to pull that air out of the tank. If you feel it hard pulling the air, then you'll know what is happening. If you get no air at all, you will also know. The key in any situation is to realize that you don't have to be in a panicked rush to do something. You have time either way to alert your buddy and begin the air sharing process. People don't pass out 2 seconds after they stop inhaling.

 

[nolatom]

I think I'd prefer to practice this on shore, close my eyes, and pretend I'm underwater. I don't like the idea of intentionally sucking a tank dry while in a non-air environment.

I have done it unintentionally though, on an ascent with more current that I expected. Tank began to breathe harder, I signalled low air to buddy, he was right there and gave me a reg. I saved the remaining air by mouth-inflating bc at surface, swam to boat on my back without reg, so passed the boat's "you have to be able to breathe from your reg at the top of the ladder or your dive trip ends prematurely" rule, though not by much, that tank was really almost empty.

A really good learning experience. Buddy said, "I'm glad you signalled low air not no air". Maybe I should've signalled no air, probably would've had to in another minute or two.

I just don't think I'd do all that intentionally.

 

[k ellis]

If you practice this one in the water I strongly recommend doing it in water shallow enough to stand in. Never practice potential hazardous situations without a good dive buddy who knows what to look for either.

As for running out of air by the time you notice it starting to go empty its too late. They will perform the same all the way till you get that last breathe or 2 out of the tank then it just completely stops and there is no way to get more air out of a completely empty tank like you would a coke bottle.

To answer your question though most people dont practice it just because its out of sight out of mind but the question you have to ask yourself is if it ever happens to you would it have been worth it to practice it?

 

[Deefstes]

Thanks so far, still keen on getting more opinions. I just want to clarify that I'm not referring to the skill of air sharing or buddy breathing. That is a skill that we practise regularly and I think we're fairly versed now. Going OOA is not a skill so I'm not really referring here to practising a "skill". I'm mostly just curious to know:
1. How my regulator would perform when the air is running out. I reckon it should be valuable to know.
2. Whether or not I would keep my wits the way I think I should if I do run OOA.

But I'm getting a general sense here of "nah, it's not really worth the risk to actually intentionally go OOA in the deep". And I guess I might as well suck a cylinder dry on my couch if I'm only interested in finding out how my reg would perform.

 

[Them]

You can get some feel for it by turning off your valve and breathing out the trapped air in your hoses. On the reg I used on my training dives the air tapered off with the valve closed, giving some warning. With the regs I have now it seems to go from smooth breathing to zero mid-breath.

I wouldn't literally suck a cylinder dry, if for no other reason than because around here I've heard the shops won't fill a completely empty cylinder without inspecting it ($$). If that's not an issue, and you know you aren't introducing contaminants, I don't know why you wouldn't....but closing the valve must be fairly close to the same feeling and is much easier.

 

[DevonDiver]

I just want to clarify that I'm not referring to the skill of air sharing or buddy breathing. That is a skill that we practise regularly...

Phew! Glad I didn't flame you then... because that's what I thought you were asking

1. How my regulator would perform when the air is running out. I reckon it should be valuable to know.

You should have done (?) two versions of the air depletion drill during Open Water training. Whilst a shut-down OOA doesn't feel identical to a 'breath down' OOA, it does give an indication of how it will feel. That, I believe, is why the skills are included on OW.

With a 'real' OOA, you might expect to notice an increase in breathing resistance for a few breaths before you cannot draw any more gas. That will depend on the regulator you are using, your depth etc etc.

For all intent and purpose, however, you can refresh your familiarity with the basic sensation simply by getting a trustworthy buddy to shut down your tank whilst you watch the gauge dip to zero as your breath. Once you're inhaling and get nothing, signal Out-Of-Air and your buddy switches your tank back on

Tips for that drill:

1) Rehearse it first on dry land
2) Do it next in water shallow enough to stand in
3) Brief and agree the exact sequence of events and the responsibilities/actions of each diver

2. Whether or not I would keep my wits the way I think I should if I do run OOA.

Psychological response to air depletion is a critical factor, that has an undeniable impact on your performance, and potential resolution, in an OOA emergency.

I believe that this response can be conditioned through familiarity. You don't need to go running OOA deliberately or doing lots of 'OOA simulations' though - just spend a little time free-diving. Learn your tolerances, extend your limits... get comfortable with the sensation of being submerged without an air source for progressively longer periods.

 

[boulderjohn]

There is a big difference between closing a valve on the surface (or shallow water) and running out of air at depth. Standard instruction requires us to turn diver's air off in the pool so they can get the sense of what it is like, but it isn't even close.

 

[TMHeimer]

Something I do once a week is mentally go over and physically go through the motions of all the skills. This keeps me on top of it should I have to demonstrate them to a student. I'm not saying at all that you and a buddy shouldn't practise OOA in the water. Don't think I would turn off air, simulate empty tank, etc. I had to demonstrate it just the other day & it went fine. Repetition. Without practise anyone can get rusty.