Deep Diving on Air

[MXGratefulDiver]

This is the Advanced Scuba Discussions forum and this subject qualifies. Given that deep bounce dives have not been unusual or especially noteworthy since the 1950s, it is unfounded to say they can’t be done safely. There is some risk and a minimum level of education and experience required just like all other forms of advanced diving.

I wonder if the folks who loved Opal would agree with that. After all, she had a pretty fair level of education and experience.

In fact, I daresay she used pretty much the exact same rationale for her final dive ...

... Bob (Grateful Diver)

 

[Akimbo]

I wonder if the folks who loved Opal would agree with that. After all, she had a pretty fair level of education and experience.

In fact, I daresay she used pretty much the exact same rationale for her final dive ...

... Bob (Grateful Diver)

If that is valid, the exact same rational must be applied to every fatality including divers recovered from less than 60' of water. Maybe we should all give up this foolish and dangerous pastime for knitting or watching Jerry Springer reruns?

 

[boulderjohn]

I don’t believe that “advocate” is a fair description of VooDooGasMan’s posts.

I think "advocate' is a very mild term. Have you read the number of threads he has started on this topic? Have you read some of the rapturous posts about how great it is to go beyond 200 feet on a single tank in other threads? Have you seen how many threads have been closed because he has so actively advocated a diving activity not endorsed by any agency, which is a violation of the TOS?

Given that deep bounce dives have not been unusual or especially noteworthy since the 1950s, it is unfounded to say they can’t be done safely. There is some risk and a minimum level of education and experience required just like all other forms of advanced diving.

I wonder if the folks who loved Opal would agree with that. After all, she had a pretty fair level of education and experience.

In fact, I daresay she used pretty much the exact same rationale for her final dive ...

... Bob (Grateful Diver)

If that is valid, the exact same rational must be applied to every fatality including divers recovered from less than 60' of water. Maybe we should all give up this foolish and dangerous pastime for knitting or watching Jerry Springer reruns?

We seem to be running into the either-or fallacy here, which seems to be pretty common on ScubaBoard lately. It isn't that dives are either safe or unsafe. A standard NDL dive is extremely safe, not not perfectly so. Going a little deeper and/or longer increases the risk, but it isn't like your going to die if you drop to 145 feet for a minute. The deeper you go and the longer you stay, the more the risk increases. When people beat their chests and brag about going all the way down to 150 feet (10 feet more than the real limit of recreational diving) for a few minutes, I have to admit that I do snicker a little.

The first real question is where does one truly draw the line? If you have the minimal training required to understand the U.S. Navy tables for air diving, do the required decompression required for the minor transgressions of NDLs, and have enough gas to do it safely, I don't have a real problem with it at all. If you are scooting down to 220 feet with a single AL 80 and hoping nothing goes wrong, I think you've gone too far.

 

[Charlie59]

I'm not sure that I get the significance of many of the posts, in that, I do not equate a dive to 165 ft to that of 225 ft or certainly 300 ft. The specific issue of exceeding the ATA of 1.6 that occurs deeper than 200 ft would seem to be something that does not come into play at 165 ft. Yet, there is little differentiation of these points on most posts. The only thing I take away from most posts is >130 ft = evil and death.

 

[boulderjohn]

The specific issue of exceeding the ATA of 1.6 that occurs deeper than 200 ft would seem to be something that does not come into play at 165 ft.

Charlie, I don't know if you mistyped this sentence. Maybe you meant something else. Could you please take a few minutes and explain what you mean by "exceeding the ATA of 1.6 that occurs deeper than 200 ft" and why you seem to think that this is what everyone has been talking about in this thread.

 

[MauiScubaSteve]

Below are a few quotes from the linked thread, circa 12/09...

http://www.scubaboard.com/forums/technical-diving-specialties/315535-deep-air.html

My point is that there are no absolutes. Diving air to 100 feet, or 130 or 150 or even 190 is not automatically the action of a staggering slob out in search of the wah-wahs.

Diving should always be responsible regardless of mixture. Diving "deep air" is like climbing Mount Everest without oxygen. It's much more difficult than resorting to trimix or heliox. It's doable, but you have to be attune to how you are feeling at that particular time and be willing to thumb the dive if need be. Your plan must be more precise and you have to be committed to the plan. Creative decision making at depth should be avoided where possible.

Historically divers have built-up their depth over a period of time. One analogy (although not to be taken in a scientific sense) may be made in looking at how alcohol affects an alcoholic. If a non-drinker consumed a similar quantity they would likely die from alcohol poisoning. The alcoholic can tolerate such high amounts by building-up a tolerance.

I'm not saying that a diver who dives progressively deeper on air is immune from the effects of narcosis, to the contrary. However with experience, s/he is more acutely able to deal with the results. One such area is that they become more aware of how narcosis will affect them and act accordingly. Problem solving accuracy and reaction time will be reduced, but these risks may be manageable if the inherent risks are accepted.

There is quite a bit of difference between deep air at 150' and 200'. Obviously the best way to do this, is under the guidance of an Instructor with deep air experience. It's great to hear that you have recognized this. Safety divers on any dive at or over 200' are a prudent precaution when using deep air.

Your attitude about deep air and trimix is an old school one. It was how I was taught as well. Times sure have changed many things. Be safe.

When I was growing-up I saved for a car, finally purchasing a used Epic for $600. I loved cars and like many 17 year old boys, I had visions of one day owning a Corvette or a Porsche. My Father told me to always hold on to my dreams and maybe one day I could afford one.

Enter a friend by the name of Lyle Griffith. His Dad was extremely wealthy (owning a company in the defense avionics industry). On his 16th birthday Lyle was given a new Ferrari.

Not everyone could be like Lyle. Thinking about it I felt sorry for him, as he never got to appreciate some of the more simple things in life that I did. I eventually owned a Corvette and a Porsche, but where was there to go for Lyle?

Historically, people would progress in diving through experience. A CCR and Trimix is like Lyle's Ferrari. There is a whole world to explore with air. Progression of experience can make deep air relatively safe. Sure it requires more dedication and planning than a routine Trimix or Heliox dive to the same depth, but that is the challenge.

Don't think it's about saving the $80 (although not everyone has that amount of money available to spend on gas). It's about doing the dive safely without the need for special mixtures and equipment. Relying on your ability to concentrate, keeping calm when facing the fear (that will inevitably present itself) and accomplishing the dive despite narcosis.

I understand however some people like Lyle can afford to bypass this experience. They sometimes simply choose an easier way. The easy way however, is not always the most personally fulfilling experience.

I have unlimited amounts of mixed-gas available to me at no personal cost. I often choose to dive deep air. It's not about saving money on a fill.

 

[smellzlikefish]

Everyone has their own personal level of acceptable risk, but how much risk is a very personal decision. A couch potato might utilize their vulgar vocabulary at the suggestion that they take up SCUBA. By the same token, questioning my comparatively liberal diving boundaries (for the count, I've been well below 130 with a single 80) will invite a suggestion involving a long walk and a short pier. I may never understand why Scubaboarders, and indeed, Scuba enthusiasts are such judgemental people. Like Akimbo said, if you really want to stay safe, don't dive.

 

[MauiScubaSteve]

Charlie, I don't know if you mistyped this sentence. Maybe you meant something else. Could you please take a few minutes and explain what you mean by "exceeding the ATA of 1.6 that occurs deeper than 200 ft" and why you seem to think that this is what everyone has been talking about in this thread.

The fact that Charlie typed "ATA" instead of "PPO2" seems pretty minor to me.

The argument of the techspurts, that we shouldn't discuss diving air from 140' deep to 225' deep because Opal screwed the pooch trying to set a personal record on a single tank below 300', has probably caused me to mistype more than once recently.

 

[MXGratefulDiver]

If that is valid, the exact same rational must be applied to every fatality including divers recovered from less than 60' of water. Maybe we should all give up this foolish and dangerous pastime for knitting or watching Jerry Springer reruns?

In some cases, I would agree with that. People sometimes die on shallow dives because they're not adequately equipped or prepared ... or because they enter the dive with too casual an attitude. Depth magnifies problems, and the deeper we go the more important adequate preparation, experience and attitude become.

What I see a lot of people doing on these deep air threads amounts to saying just jump in the water and hope for the best. That's not what I think we should be advocating on a public forum ... in fact, it's pretty irresponsible. The "everybody does it" argument isn't very valid. Everybody doesn't do it ... in fact, I'd bet the deep air crowd is one of the smallest ... and lately most vocal ... minorities on ScubaBoard. For good reason.

... Bob (Grateful Diver)

 

[TSandM]

No, Charlie, what you should be taking away is that the margin for error gets smaller and smaller as the depth gets deeper, and the resources you have to deal with issues get more and more meager.

Inadequate decompression killed Opal and seriously injured her companion -- but why did they do inadequate decompression, and how did they end up needing it in the first place? The answer to the latter was impairment due to narcosis, and the answer to the former was that they didn't have enough gas for what they ended up needing to do. You can cope with many, many things underwater, if you have the gas supply to do so -- but the deeper you go, the bigger your supply has to be, and it's compounded by the implacable ticking away of the decompression clock, too.

In the classes I've taken, we were originally taught to allow one minute to recognize and resolve an emergency on the bottom, after which we would begin our direct ascent. In practice, NOBODY gets the job done in a minute. At 7 ATA (200 feet) with an average SAC rate of .7, you're using almost FIVE cubic feet of gas per minute -- take three or four minutes to resolve an issue, and you have used almost a third of your aluminum 80 tank right there. The point we are all trying to make is that you're cutting it very thin, and the deeper the dive, the thinner the margins. When you add narcosis, slow reaction times and confusion to the mix, it seems awfully likely that ANY mishap will end up with somebody out of gas. Out of gas, out of time, out of options.