Deep Diving on Air

[dumpsterDiver]

Peter,

Sorry, but I do have a great understanding of the issue and I do also have my own opinion on it. If you look at my previous posts on this thread, you will see that my opinion is against deep air.

The meaning behind my statement is simple. There are 2 camps firmly divided on the subject, and no matter how much is written on an internet forum, the likelihood of changing the opinions of either of those 2 camps is negligable. Unfortunately, all people believe their own opinion is valid, regardless of what others think, so merely stating that some opinions are not valid, is only your opinion, which others may argue in itself is not valid .

Hence the reference to round and round in circles as well.

Yeah, but...These types of discussions might help people who have not yet formed a strong opinion formulate their own. I agree that the people who have given the topic a lot of thought and are polar opposites are probably never gonna come to a consensus.

You gotta admit though, the DAA (deep air advocates) sure look kinda wacky in this thread.

 

[Tigerman]

Lets count minutes prior to this hypothetical rescue. Even if the diver was lost as soon as he/she hit bottom, they'd have spent a minute or two descending, five minutes for the buddies ascending, five more minutes swapping tanks and gearing up for the rescue, and another minute or two descending again. That means it would have been 14 minutes that this diver had been down before you even got to their depth, and you haven't even found them yet. There's no need to rush a body recovery.

Personally, although no fan of deep air dives with single tanks etc myself, I find this to be a bit too much of a blanket statement.
14 minutes for a LOST diver may be an inconvenience as we dont know about his/her gas supply or what the nature of being "lost" is.
That a diver is lost does not automatically mean the diver is out of gas or in actual trouble.
Any number of things could be the issue as long as the diver is just "lost". (S)He could be out of gas at 300' or tangled up in something with plenty of gas in the tank at 50'...
Then of course there is the issue of wether or not the divers who just surfaced can safely decend again to begin with.

 

[Rhone Man]

Yeah, but...These types of discussions might help people who have not yet formed a strong opinion formulate their own. I agree that the people who have given the topic a lot of thought and are polar opposites are probably never gonna come to a consensus.

You gotta admit though, the DAA (deep air advocates) sure look kinda wacky in this thread.

Those are two very well made points.

My view on the subject has been pretty consistent. I certainly see the sense of advocating that everyone use trimix in helium rich and extremely safety conscious North America. But I think in many other places in the world, deep air has its place. But it is riskier, and that is why it is important that proper training be available (to stop goobers doing 200 foot dives on single tanks), and that people are able to make realistic assessments of their own ability to deal with narcosis.

My view won't change the opinion of anyone who has already picked a side in the debate. But I like to think that undecided people would read it and weigh it on its merits.

 

[DCBC]

... But it is riskier, and that is why it is important that proper training be available and that people are able to make realistic assessments of their own ability to deal with narcosis.

Well said! There are several applications of sport diving with an increased level of risk; CCR, wreck, ice and cave diving are a few other examples. Risk is not limited to deep air. It must be left to the individual to assess risk. Who is another to tell you or I that a particular type of diving is too risky? I have witnessed inexperienced divers in a wreck taking more risk at 50' than experienced divers on air at 200'.

 

[MXGratefulDiver]

Those are two very well made points.

My view on the subject has been pretty consistent. I certainly see the sense of advocating that everyone use trimix in helium rich and extremely safety conscious North America. But I think in many other places in the world, deep air has its place. But it is riskier, and that is why it is important that proper training be available (to stop goobers doing 200 foot dives on single tanks), and that people are able to make realistic assessments of their own ability to deal with narcosis.

... and if the discussion were framed in those terms I'd have little to say. My objections have far less to do with narcosis management than they do with the attitude that deep air diving is somehow a "shortcut" for those who want to dive beyond recreational depths but don't want to be bothered getting trained for it.

The OP doesn't give us any information about his training, but leaves the impression that he did a 175-foot "trust-me" dive on a single cylinder. I find the attitude that would allow someone to decide to do that dive far more worthy of objection than the choice of breathing gas they did it on ...

... Bob (Grateful Diver)

 

[CaveMD]

*I'm referring to the central Florida folks, Hal Watt's outfit, who teach deep air to 240 ft, and TDI's Extended Range course, which as I understand, is rarely taught as there is an awareness that adding helium is a better idea for deep dives. Can't remember the acronym for the first agency.

PSAI

Professional Scuba Association International

Narcosis Management

Level I 30m (100')
Level II 40m (130')
Level III 45m (150')
Level IV 55m (180')
Level V 60m (200')
Level VI 67m (218')
Level VII 73m (240')

 

[Tigerman]

By that I assume PSAI recommends a max pp02 of 1,8 rather than the 1,6 some other agencies adhere to?

Or do they use 1,7? (73m is ~1,74)

 

[Tigerman]

[Double post]
Ooops
[/Double post]

 

[Akimbo]

… But it is riskier, and that is why it is important that proper training be available (to stop goobers doing 200 foot dives on single tanks), and that people are able to make realistic assessments of their own ability to deal with narcosis….

There is no doubt that people do learn to manage narcosis (not make it stop or irrelevant), but it requires a slow and repeated exposure that allows individuals to recognize symptoms and develop a mindset that makes the effect far less hazardous. Sure it changes daily and is heavily influenced by harsher environments. That just intensifies the need to progress deeper slowly, contemplate experiences, and recognize moving boundaries. No class can provide that level of experience, only the knowledge of how to safely self-educate.

Commercial divers have that aspect of learning easy because we get a lot of training, and most undergo an apprenticeship of sorts. We get to take chamber rides, have virtually unlimited air and can communicate with diving supervisors with a wise ear trained on the speaker. They also precisely know our depth even though we don’t (unless they tell us). The risk of getting too deep on air is very slim and will get your butt yanked shallow with little provocation.

Any experienced deep air diver will tell you that narcosis is not sudden or debilitating, unless you aren’t paying attention or haven’t experienced it enough to recognize symptoms. It can easily make you real stupid until you develop a sense and compensate for it. Compensating includes moving towards sunshine as needed. No class can teach it.

 

[Potapko]

Those costs aren't very far off what we pay here in Seattle. A 25/25 fill in my double 85s runs me around $40 (I get a good discount due to a membership plan). Charter fees here run around $85 for a two tank day, so $40 to $45 per dive. I'm not sure what my O2 runs me, but I think it's around $10 for a full 40.

If I don't think the dive is worth the cost, I don't do the dive.

I hate to admit it, but this is probably the main reason why people over here do not use trimix. A fill of that same gas here costs about $100. There are a great many people here who dive "tech air". Fully equipped and prepared for the dive in quantity of gas and plan, but just don't have the money to buy the helium. So, we may tell them it is not smart to do the dive, but the fact is that air is the only chance they have to see many dive locations. So they risk it.

I wrote a report about the friend we lost in lake Attersee in Austria. Argued with him the night before that even though he went to 90 meters in Egypt in 23c water, doing it in a 4c lake was a real bad idea. They found his body 4 days later at 70 meters with empty doubles and a full deco tank. Comp showed a max depth of 90m. He was convinced he could handle the narcosis.

Most people can handle the narcosis until the excrement impacts the ventilator. Of course to various levels.
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