Deep Diving on Air

[captain]

And speaking of which, don't believe that nonsense that 130fsw is because it works out to a PPO2 of 1.0 ATM ... the historical reality is that the USN divers started with Steel 68's and the bottom time at 130fw simply wasn't sufficient to get any useful work done...as such, it was mission-pragmatic, not physiologically based as we've all been lead to believe.


-hh

And that still applies to Navy divers today using open circuit scuba. The early training agency simple cherry picked the 130 foot number with or without any thought as to why the Nave chose it. In actuality the Navy's max operating depth on open circuit scuba on air was 200' for short duration, < 15 min. dives. It was based simply on the amount of breathing gas available.
See the 1958 Navy diving manual, self contained diving section, page 9, table 3.1

 

[-hh]

And that still applies to Navy divers today using open circuit scuba. The early training agency simple cherry picked the 130 foot number with or without any thought as to why the Nave chose it. In actuality the Navy's max operating depth on open circuit scuba on air was 200' for shot duration, < 15 min. dives. It was based simply on the amount of breathing gas available.
See the 1958 Navy diving manual, self contained diving section, page 9, table 3.1

And when we go back far enough (but not really all that far), we find many other examples that illustrate just how the industry was cobbled together based upon the Miltary-Science-Commercial practices of the day.

For example, when I finally took my OW Class, the instruction included class quizzes for the stops for staged deco diving to 180fsw on air. When we asked the instructor as to why, his explanation was that this was applicable to the local diving scene. Specifically, it was what we could be expected to be doing as rec divers withn 2-3 years when diving on the "Texas Tower" Over time, risk aversity has evolved and no one would even consider doing a 180fsw dive on air, let alone a novice with probably only ~50 dives after OW-I doing that with a set of twins (and probably only a 1/4" Farmer John wetsuit).

Plus, there's been new technologies that provide other options. It may be hard to believe, but less than twenty years ago, the Rec dive industry was trying to ban Nitrox as an evil "Voodoo Gas", even though it had been used for decades by institutions such as NOAA (and was in their diving manual). For example, this post refers to the 11/92 issue of Skin Diver Magazine which was basically endorsing a ban on Nitrox for Rec Divers (update: here's another, probably better, link).

I'll have to go find that issue in a local library to read it with modern insight. But it does show just how much perspectives on the issues have changed, when the industry realized that it wasn't necessarily 'evil' when it was profitable.



-hh

 

[DCBC]

Lamont, accidents happen everywhere; in wrecks, caves and in shallow/deep water, on air and with mixed-gas. What we don't need is someone choosing what risks are allowable and throwing stones at others diving choices. What's "within the lines" is a matter of personal perspective and choice. Adults make their own decisions, reap the benefits and at times pay for them. I don't promote anyone using deep air any more than cave diving before being trained. I hope that common sense prevails but what's reasonable for one person, often is not for another.

 

[MXGratefulDiver]

Adults make their own decisions, reap the benefits and at times pay for them.

If only that were true ... unfortunately, we live in a world where people only want to reap the benefits of their decisions, and make someone else pay for the liabilities of them.

When a diver gets injured or killed, there is almost always someone else on the hook for the consequences of that diver's decisions ...

... Bob (Grateful Diver)

 

[lamont]

Lamont, accidents happen everywhere; in wrecks, caves and in shallow/deep water, on air and with mixed-gas. What we don't need is someone choosing what risks are allowable and throwing stones at others diving choices. What's "within the lines" is a matter of personal perspective and choice. Adults make their own decisions, reap the benefits and at times pay for them. I don't promote anyone using deep air any more than cave diving before being trained. I hope that common sense prevails but what's reasonable for one person, often is not for another.

Well that isn't what you need, but I'm perfectly happy to throw stones at this idea.

We've been down that path, we know how to get there more safely now. We don't need deep air. We definitely don't need people training up others on deep air now, and it shouldn't be acceptable.

Adults can make all kinds of decisions, including stupid ones, like this.

 

[Steve50]

If only that were true ... unfortunately, we live in a world where people only want to reap the benefits of their decisions, and make someone else pay for the liabilities of them.

When a diver gets injured or killed, there is almost always someone else on the hook for the consequences of that diver's decisions ...

... Bob (Grateful Diver)

Especially in the United States of "It's Not My Fault"

 

[DCBC]

Lamont;

One could say the same of Cave and Wreck diving; stupid people taking unnecessary risks. I don't however share this view and obviously disagree with your perspective.

 

[DCBC]

If only that were true ... unfortunately, we live in a world where people only want to reap the benefits of their decisions, and make someone else pay for the liabilities of them.

When a diver gets injured or killed, there is almost always someone else on the hook for the consequences of that diver's decisions ...

... Bob (Grateful Diver)

Yes, this is true to a point Bob. In a Society we each share the social burden. We pay higher insurance rates because of wreckless drivers and those who DUI. Society also bears some financial burden for those who are lazy and don't want to work. At the same time we live in a free country. I enjoy that freedom and don't look forward to the day that someone can suggest that I don't dive in a wreck or a cave (after I've been trained to do so) solely because I place myself at a higher risk and that choice shouldn't be tollerated by society!

Those who deny freedom to others deserve it not for themselves.
Abraham Lincoln

 

[Kevrumbo]

Let's be objective with a real world example of the risks involved (non-contributing, glip & flippant, contemptuous "holier than thou" & self-righteous posts like Lamont & Bob's above aside):

If you're in warm tropical 27deg C waters, no current, good viz, on an external easy tour of a wreck (like in Truk Lagoon, where I'll be in two weeks), you can cognitively accommodate to deep air. You have trained muscle memory to handle most contingencies albeit you may be slower to process, problem solve and react . . .so you strategically mitigate your activities to avoid potential tactical overload in an emergency situation --i.g. don't penetrate the wreck; don't physically exert yourself to CO2 retention levels & starting the vicious dark narc cycle; don't do any extensive computations on-the-fly to your deco schedule; go no deeper than 60m or ppO2 1.47 etc. --keep it all nice, easy and simple. . .

That above being said, in my experience . . .here's what can start to "innocuously" happen while on Deep Air:
You can compensate for the narcosis with increased concentration on the task at hand, but unfortunately that may come with the detrimental loss of overall "situational awareness": for example, you can consciously concentrate hard in tying in a clean secondary tie with your penetration reel, but you then inadvertently tangle your SPG in the process, in addition to silting-out the passage behind you (actually happened to me inside the Nippo Maru). Plus, it takes more time to problem-solve and assess contingency scenarios when you're cognitively impaired; your margin for recoverable mistakes & errors of judgment becomes less and less; you become more susceptible to being overwhelmed by cascading adversity (i.g. tangled penetration line, followed by a primary light failure, with your buddies signaling that you're at thirds SPG Pressure-turn-around-to-egress). . .

 

[MXGratefulDiver]

Have fun Kev ... try to stay alert and not bend the crap outta yourself this time ...

... Bob (Grateful Diver)