What is the deepest you can do an OOA?

[JeffG]

True enough, but... why not practice both?

Fin...exhale. Tough skill. I better practice, I might forget how to do it.

 

[Rick Murchison]

Fin...exhale. Tough skill. I better practice, I might forget how to do it.

No, you won't forget. So don't practice it. There are probably lots of other things that fall into the same category and the same logic can be applied. You know, "S" drills and valve shutdowns and all that kind of rote stuff... just makes no sense to practice those either, eh?
Rick

 

[MikeFerrara]

Your scenereo had two divers with four posts (two a piece). So in other words, no one should be diving unless they are diving doubles or, at the very least, a Y valve? That'll be a tough sell in the dive industry. If that is where you are coming from, I can't really argue except to say that the dive industry would become a much smaller place, and a lot fewer dollars would go into development of the gear you use. Also, volume sales of gear would plummet, which means everything costs you considerably more.

My intention was to address the situation presented with how I wouldrespond. I'm not responsible for deciding how everyone else should do or what the dive industry as a whole should do. I'm not trying to sell anything to the industry. I already know that's a lost cause. I'm not concerned with the size of the dive industry or the amount of money they have for development...they mostly develop pretty colored, style oriented junk that appeals to the fashion consious tourist and I have absolutely no use for about 99% of it.

If your argument comes strictly from a cave or deco standpoint, I can't argue, except that in the case of a deco dive, some extreme and highly improbable (almost beyond imagination) circumstances could leave the surface as the best alternative.

I didn't pose an arguement at all however, whether the overhead is real or virtual the effect can be the same. There may be some situations where you might opt to shorten decompression to reach the surface sooner but the more decompression you owe the worse of an idea that becomes.

Regarding decompression, I viurtually never plan a staged decompression dive as a single gas dive. That means that I not only have my bottom mix (or backgas) but I have one or more decompression gasses. The dives are planned such that I have sifficient gas volume to complete decompression with the total loss of any single gas. Each diver also has enough gas to get a buddy up, so again, it would take a bunch of failures before "the surface" is the solution.

In fact, I view failures like flooded dry suites and the like as much greater risks on long dives that a loss of gas. A flooded suit in cold water with a significant decompression obligation could make for a lousy day.

Something that did happen once that made me think was a cave dive where I became ill. Nothing too serious, I just ate the wrong thing for lunch at the local corner store and got the worst case of heartburn, gas and acid coming up my throat that I've ever had. Not too big of a deal except that I was forty minutes or so back in a cave when it happened. The trim I had to maintain in order to swim out of that cave did absolutely nothing to encourage the contents of my stomach to stay in my stomach. Had it ot been for all that rack over my head, I would have been headed straight for the surface.

But a buddy pair of rec divers diving singles well within no deco limits and well within the recreational depth limits (read: under 100 ft.) have a very, very slight chance of multiple equipment failures which could lead to the necessity of a CESA. Under the same circumstances, poor gas management (yes, we are human) can also lead one diver to be on the other's alternate, heading for the surface, at the time that the buddy's reg has some form of catastrophic failure.

At 100 feet (and usually much shallower) you'll usually see me using an h-valve or my doubles. I don't care what anyone else does but as far as I'm concerned a single tank with a sinle output valve is for nothing but really shallow easy dives. I don't do "deepish" dives or dives that are very challenging in any way with "instbuddies" either. again, I don't care what other people or the "industry" does. The "industry" is absolutely overflowing with examples of what NOT to do, as far as I'm concerned.

Do I forsee myself ever having the circumstances that would necessitate me using this procedure? NO! Do I keep it in my back pocket in case things ever really do go brown down there, either through my own screw-up or through hellacious circumstances? WHY NOT? No need to buy any additional equipment, no major investment of time in the training, just an occasional controlled exercises once in a great while? What exactly is at risk here?

If you don't forsee any time that you just might need to use this procedure, and therefore have chosesn to remove it from the tool box, that is your call. God bless, and hope you never need it. For the small investment, I'll keep it around, whether I feel I will ever need it or not. I really have nothing more to say on the subject.

I couldn't remove it from "my toolbox" if I tried since I've done hundreds, if not thousands, of practice CESA's. Still, I've never had to do one in a real OOA situation and I doubt I ever will. That would be a good thing since many of my dives are with some sort of overhead barrier.

 

[MikeFerrara]

<shrug> With 85-ish dives under my belt, I have never felt the urge to bolt for the surface. My wife, with 60-ish dives under her belt, hasn't felt that urge since her second checkout dive. We've had an occasional issue that has come up. We have dealt with it and continued the dive, or we have thumbed the dive. I never felt that CESA exercises instilled in the divers that bolting to the surface is a solution to all problems. If you feel it has, I can understand the rest of where you are coming from. It hasn't been my expeience.

I've seen quit a few divers bolt for the surface. Only one was low on breathing gas...BTW that was a dive on the Papoose. A 120ish dive on a single 80. That diver was in a hurry but not paniced. I don't do dives like that with that sort of equipment anymore and even on that dive, my wife and I decided that the rest of the group were nuts when they headed off and we stayed near the line and headed up really early. We were hanging around at shallow depths watching the jacks and the cuda when all the other divers came rushing up the line with barely enough gas left to get to the surface.

All the other divers I've seen opt for the surface had plenty of gas.

 

[MikeFerrara]

Rick-

If anything I have said is out of line with this, I hang my head in shame. I am 100% in agreement. Personally, I don't think anything I said was.

I too agree with Rick but...I still think that the most useful way to discuss this is to take some problem examples and discuss how we would manage or avoid them. Somewhat realistic examples are beter than "my gas just magically disappeared right after all my equipment broke and aliens kidnaped my buddy" type.

The buddy problems are good to discuss, IMO. the way we (my buddies and I) dive, a divers first priority is their diving and team responsibilities. On a simple dive the "team responsibilities" are also simple but they come FIRST. We don't "sight see", take a picture or anything else in a way that compromises situational awareness or our ability or readiness to respond to a problem. The most basic aspects of this often aren't taught or tested in mainstream training. Still, without it, you're essentially solo diving and then you should be rigged for solo diving, IMO. Lots of recreational divers are really solo diving only they don't realize it and aren't equiped or otherwise prepared for it. Again, as I said before, you can't do everything wrong and expect things to always turn out right.

 

[GDI]

As I read this thread I can see common themes regarding OOA.

Ok first if all it is unacceptable to run OOA plan your gas correctly (this has been covered here)
Second a cylinder doesn't just empty immediately, just like that, with nothing to breath There is some increased resistance to the breathing ability which if you didn't notice leaves me to question your diving awareness skills
Thirdly considering the physics at play here one must ask themselves - Are they willing to roll over and die or would they do everything in their power to make it to the surface? Death is really a bad way to end a diving career in that it is sort of a permanent condition. On the other hand living with an injury or illness that prevents you from ever diving again may not be a bad thing? The diver needs to make a choice -

that is decide to live or die.

The whole concept of the CESA is using Boyles law to our advantage. This law just keeps coming back at us doesn't it? The whole thing about releasing air as we ascend to prevent a lung rupture sounds pretty scary to a new or inexperienced or unpracticed diver (poorly practiced skills have the same effect as not having any skills).

The equipment aspect of diving seems fairly straight forward. We claculate the gas we need for doing the dive we plan (You do plan don't you?), we get that amount of gas or greater. (I don't recall anyone ever complaining of having to much gas). We confirm the gas's enrichment and pressure then we set it up and hit the water. During the dive we monitor it by a little thing known as an SPG. Yes this seems like a fairly simple concept. Yet people do fail at it so we've developed skills like the OOA CESA.

The depth to which this skill can be performed successfully even under the hypothetical worst case scenario really comes back to the divers decision making ability and determination. The choice to make is to live or die, a clear choice to make IMHO.

Would you give up and stop your ascent 20,30 or even 60 feet from the surface because you completely expelled your lung's air capacity? Would you be willing to risk a form of DCS or AGE to make sure you at least take that possibly final breath of fresh air?

Between the choice of life or death I would be willing to violate a deco stop or the ascent rate because I choose to live. Say what you want but this is what it gets down to.

The OOA CESA can be performed from any depth as long as you are willing to make the attempt and accept the new sets of risks you have placed upon yourself because you failed to monitor your air supply.

We have conducted tests, foolishly or otherwise doing this very skill from depths greater then 130 feet and successfully in that no DCS or other malidy resulted. The problem here is that in doing these tests, is that we had the correct amount of gas available, and we were not imposed upon by an actual sitiuation. Basically we were in controll. It is here though that should this OOA situation actually occur that training and testing would allow us to most likely successfully get through it from greater depths.

Considering the aspect here of depth and water tension (resistence to ascent) the equipment the diver has available combined with the diver's knowledge we can use that good old boyles law to assist us to a greater extent.

We know we need to release air from our bodies to prevent lung expansion injuries. We have equipment that is designed for buoyancy control...

Possible solutions should now come to mind????

The Air in the BCD is direct from the cylinder it is breathable air. A diver has the ability to breath off the BCD through the inflator. Combining this with the CESA a diver can safely ascend meeting the requirments of Boyles law extending that ascent depth.
In the advent that even this air source were to be so reduced and the diver is still not at the surface, the diver can exhale into the BCD adding lift to themselves. Higher risk? Yes But you will be at the surface. The expanding air within the divers lungs is simply transferred to the BCD. This is a more advanced version of the CESA using knowledge of the equipment and the physics of diving. THE MORE YOU KNOW THE MORE FUN IT GETS. Just make a decision choose to live or choose to die.

Of course not running OOA by monitoring it will negat this concern
Safe Diving to everyone and Merry Christmas

 

[MXGratefulDiver]

I couldn't remove it from "my toolbox" if I tried since I've done hundreds, if not thousands, of practice CESA's.

People sometimes forget that instructors have to demonstrate a CESA in every OW class, and accompany each student in the class to the surface as they do theirs.

Most (competent) instructors could probably do this "skill" in a coma ...

... Bob (Grateful Diver)

 

[Tigerman]

People sometimes forget that instructors have to demonstrate a CESA in every OW class, and accompany each student in the class to the surface as they do theirs.

Most (competent) instructors could probably do this "skill" in a coma ...

... Bob (Grateful Diver)

And indeed they did in my OW class.. Dont remember exactly what depth it was from, but it wasnt any problem getting to the surface.. I certainly still wouldnt consider a CESA from 100+ to be a real option tho..

 

[Diver Dennis]

OOA at 100' and no buddy around? To me, everything would be an option.

 

[HowardE]

And indeed they did in my OW class.. Dont remember exactly what depth it was from, but it wasnt any problem getting to the surface.. I certainly still wouldnt consider a CESA from 100+ to be a real option tho..

It's more of an option than drowning