Exactly how deep is "Deep Air?"

[Cave Diver]

Ok, moving on...

 

[DCBC]

I'm interested in answers based on your personal assessment of narcosis and the point where you feel it adversely affects your ability to safely manage it.

If the dive is above 150', I will usually do the dive on air, regardless if Helium is available. Between 150-200' I'll use air unless the dive is long and strenuous and Helium is available. Below 200', I prefer to use Helium but will dive air if the dive is relatively short and not strenuous. I will only use Helium over 250'. I have used air in a chamber to 300' as a test subject. The results of my performance convinced me to limit my maximum depth on air to 250' (for short periods).

For me the choice of gas has to do with the planned length of the dive, the level of exertion expected, the complexity of the dive at depth and the depth itself. Obviously the availability of Helium is also a factor.

 

[DCBC]

What you really need is two polls.... one for people who are trimix trained, and one for those who aren't. I'd certainly be interested in seeing the difference.

I don't think that you need two polls. Many Trimix divers have predetermined that they need Helium past a certain depth and insist on using it beyond this. I suspect that many of these have never contemplated diving deep on air. Divers that don't quickly migrate to Trimix tend to develop their ability to function safely (over longer periods to increasing depths) in a modular way. The Trimix diver never adapts to do this in a similar way, as he uses Trimix and doesn't have to. It is interesting to read why people feel the way they do.

So I can see why some groups recommend an END of 30m. There are enough people out there who do get seriously narc'd at those depths - so why not be conservative?

This is reflective of several areas of society. People want to go deep and they want to be able to do this quickly. Enter Trimix. A number of these divers could be diving to similar depths safely on air, but it would take time for them to learn and adapt. People nowadays don't seem to have the time for this.

Bottom line in this debate is, I think, that a subjective opinion is based on personal experiences. But it is also important to remember that just because something hasn't gone wrong (yet) that it makes the activity safe. I'm not being down on deep air, but I would say that I think the only way to have confidence in a personal limit for an END is to put yourself through some form of controlled (but unexpected) foul up situation at depth and see how you respond.

Yes, this can be said about diving caves, wrecks, ice, CCR, decompression, etc. just because something hasn't gone wrong yet, doesn't make the activity safe. Diving itself places a person at increased hazard. We each choose what risks are acceptable and the ones that aren't.

Chambers don't quite cut it, the environment is so different. I don't have any focus on a 50m chamber dive, so how I behave is radically different from a 50m (air) dive.

If the chamber dive is done properly, it does cut it. The first mistake people make during a chamber ride, is what you've suggested: "no focus." That doesn't mean the person can't have focus, but they choose not to. There is a difference between 300' in a chamber and 300' in openwater on air, but as I've already mentioned, with my chamber results at that depth, you'll never find me in openwater at that depth unless I'm breathing Helium. On the otherhand I will dive up to 250' on air because of the chamber results at that depth and my diving experience diving deep air.

Andy, I agree that it would be a good idea for a diver to go through chamber testing to give them an understanding of their problem solving abilities at depth. Unfortunately, most will be unable to volunteer at a hyperbaric facility.

 

[Tortuga68]

I voted 45m+

In the warm, tropical conditions that I usually dive I'm comfortable to dive air to that depth with my regular buddies

I'll use nitrox on 30m+ but for the NDL benefits rather than avoiding narcosis

I've been to 75m on air and have been "okay" IMO but would defintely consider it 'deep air' and recognise the associated risks

Actually these stories are adding considerably more interest to these threads than earlier deep air threads. I always teach my students (non-diving context here) that you learn more from mistakes than from successes, so I hope a few others are brave enough to post their stories

I did 55m on air recently... I was a little light for weight on the descent, I knew it, my buddy knew it. After 10 minutes at 55 we found a weight pocket, with 8# in it. My buddy clipped it on, but found it to much work to carry, so he ditched the weights

Neither of us thought about me taking one weight to resolve my buoyancy issues, until we were at our first stop at 30m. So yes, we were narc'd and not thinking straight

 

[Tortuga68]

I use my depth gauge to determine if I am narced

This would seem to imply that your level of narcosis is the same regardless of conditions?

 

[scubadada]

We don't need more andecdotes. Narcosis and diving comfort is subjective and indvidual. I'm OK to 150', below that, I'm very careful. That's how I voted.

Good diving, Craig

 

[Tortuga68]

We don't need more andecdotes

How very Dadaist of you

 

[The Chairman]

This would seem to imply that your level of narcosis is the same regardless of conditions?

No implication needed... re-read the entire post for a full understanding.

Feelings can get you killed. Both euphoria and panic (and everything else in between) are induced by narcosis. The difference between experiencing one or the other can be minimal and I have seen divers switch moods in a thrice. There are several mitigating factors for "feeling" narced at any particular depth... but those are simply feelings. You are still impaired whether you feel like it or not. The most dangerous diver is the one who is convinced that narcosis does not affect them. Narcosis must be either avoided or managed in order to dive safely.

 

[UCFKnightDiver]

I don't think that you need two polls. Many Trimix divers have predetermined that they need Helium past a certain depth and insist on using it beyond this. I suspect that many of these have never contemplated diving deep on air. Divers that don't quickly migrate to Trimix tend to develop their ability to function safely (over longer periods to increasing depths) in a modular way. The Trimix diver never adapts to do this in a similar way, as he uses Trimix and doesn't have to. It is interesting to read why people feel the way they do.



This is reflective of several areas of society. People want to go deep and they want to be able to do this quickly. Enter Trimix. A number of these divers could be diving to similar depths safely on air, but it would take time for them to learn and adapt. People nowadays don't seem to have the time for this.



Yes, this can be said about diving caves, wrecks, ice, CCR, decompression, etc. just because something hasn't gone wrong yet, doesn't make the activity safe. Diving itself places a person at increased hazard. We each choose what risks are acceptable and the ones that aren't.



If the chamber dive is done properly, it does cut it. The first mistake people make during a chamber ride, is what you've suggested: "no focus." That doesn't mean the person can't have focus, but they choose not to. There is a difference between 300' in a chamber and 300' in openwater on air, but as I've already mentioned, with my chamber results at that depth, you'll never find me in openwater at that depth unless I'm breathing Helium. On the otherhand I will dive up to 250' on air because of the chamber results at that depth and my diving experience diving deep air.

Andy, I agree that it would be a good idea for a diver to go through chamber testing to give them an understanding of their problem solving abilities at depth. Unfortunately, most will be unable to volunteer at a hyperbaric facility.

What exactly are you learning? Learning to adapt? It has been shown in studies that this is not the case, there really isnt learning to adapt, only getting comfortable with skills that let you lead a normal and uneventful dive. When the **** hits then fan you're going to be just as impaired and screwed as anyone else. More to the point though, why the hell would I need, or want to *try* to learn to dive intoxicated when there are better methods and tools for the job?

 

[The Chairman]

This is reflective of several areas of society. People want to go deep and they want to be able to do this quickly.

This is more reflective of your macho baditude towards diving and other divers. No one who has gone this route has mentioned "speed" at all. They all seem to indicate "safety" as their primary reason for utilizing He at depths.

Using your rationale, maybe we should learn to drive while intoxicated? People who call cabs are reflective of a society who only wants to get home quickly instead of braving the macho adventure of driving home impaired.

There is nothing wrong with caution and utilizing an alternate method to accomplish the same mission safely and within your individual comfort level. Kudos to the divers who don't drink and drive as well as those who take precautions to stay safe while diving.