Diving air to 60m

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John Bantin

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Diving to 60m (~200’) on air?
During the 1990s and 2000s, I repeatedly took groups of divers to that depth to compare the performances of a range of regulators. We used air because it was the most challenging gas for a regulator to deliver. They each made detailed notes at that depth that independently corresponded to the findings of the others. Nobody even suffered narcosis because I always chose COMPETENT and experienced divers. We did the same with computers, to get true comparisons of in-water performance. Some readers complained that we did it in the Red Sea so one February we went to northern Sweden to do it. It was colder, that is all!


A ScubaBoard Staff Message...

This thread has been created out of a thread in A&I about a death that occurred on a dive to 60m. No official cause has been determined in that fatality but this discussion is completely outside the rules of the A&I forum and is not conducive to the further discussion of that accident. Please be respectful. Insulting other members will result in a loss of posting privileges in this thread.
 
During the 1990s and 2000s, I repeatedly took groups of divers to that depth to compare the performances of a range of regulators. We used air because it was the most challenging gas for a regulator to deliver. They each made detailed notes at that depth that independently corresponded to the findings of the others. Nobody even suffered narcosis because I always chose COMPETENT and experienced divers. We did the same with computers, to get true comparisons of in-water performance. Some readers complained that we did it in the Red Sea so one February we went to northern Sweden to do it. It was colder, that is all!

I don't get your anecdote... unless you are trying to make the argument that diving air (and a 12L) tank to 60m has nothing to do with the fatality?

Or do you want to start a "deep air is safe" discussion... really in 2019?

Yes... I started diving in 1990, yes I dived deep air (so have loads of people), have you read Drs Mitchell and Anthony's study on gas density?

Alert Diver | Performance Under Pressure
 
Diving to 60m (~200’) on air?

A couple of weeks ago, a friend of mine sent me a photo of his computer at depth showing 207ft. I asked what kind of gas, how much did he carry and how much deco was incurred. His reply, "Air shore dive so just by swimming in you doing deco." He didn't mention how much, but I know he was diving air in an AL80. I haven't seen him yet to get the details.

He's an experienced diver and a commercial diver to boot, so I was surprise that he did such a dive and my impression by him sending me the photo, it seemed be for the depth.
I've only dived with him a couple of times many years ago when my then dive buddy was taking his wife out for her check out dives for her certification, so I really don't know how he dives for recreation. With dives like that, I doubt I ever will.
 
Diving to 60m (~200’) on air?

I've done many dives to 200 fsw on air. One day I average 180 fsw on three dives (200, 180 and 160 fsw). I certainly don't recommend it to anyone else though.
 
Diving to 60m (~200’) on air?

OxTox time is longer than NDL of ~5 minutes (by the tables that go that deep) and a bounce dive like that should be doable on an AL80, provided you're not hyperventilating from all the excitement. Gotta wonder what's down there to see in a couple of minutes, that was worth the risk, though.
 
OxTox time is longer than NDL of ~5 minutes (by the tables that go that deep) and a bounce dive like that should be doable on an AL80, provided you're not hyperventilating from all the excitement. Gotta wonder what's down there to see in a couple of minutes, that was worth the risk, though.

I'm not worried about Oxtox at that depth diving air. There is some "evidence" that N² narcosis decreases the risk of a CNS hit.

I would be worried about breathing air that feels like breathing pudding at that depth (no matter the type or reg you are using), and hypercapnia. Specially in this scenario where there might have been a BCD malfunction, possible increased breathing rate, etc. In short not being able to ventilate the build up of CO², creating a dark narc, maybe panic. But this is all hypothesis.

What I do have experience with is the effects of gas density and hypercapnia on your narcosis level. Take a nice drift dive to 50m using air in the red sea and nothing will happen. Do that same dive but suddenly you need to fin as a madman against current (brothers isles for example) and suddenly the whole picture changes. Your lungs just can't overcome the effect of death space and gas density and cannot expel CO² sufficiently creating a vicious loopback where you are retaining more and more CO², feel more and more out of breath. But even before you feel out of breath your narcosis level will increase a lot. Same dive, different circumstances. This is fysiology and no experience or competence will change this.
 
During the 1990s and 2000s, I repeatedly took groups of divers to that depth to compare the performances of a range of regulators. We used air because it was the most challenging gas for a regulator to deliver. They each made detailed notes at that depth that independently corresponded to the findings of the others. Nobody even suffered narcosis because I always chose COMPETENT and experienced divers.

200' on air. Did you actually say this with a straight face?
 
You younger/newer divers do realize that dives like on the Andrea Doria were made often on air, with steel 72s, no bcd’s, no octo?
Just because there are other options now doesn’t make deep dives on air the kiss of death.
Scuba diving can’t be made perfectly safe. You sometimes just do a gut check and do it anyway. As long as you aren’t reckless about it you will be ok.
 
I am still trying to figure out how competency and/or experience have any bearing on whether or not you experience gas narcosis. Those might affect how you react to it and/or deal with it, but whether or not you "suffer" it?!?

Nobody even suffered narcosis because I always chose COMPETENT and experienced divers.
 
I think we've learned a lot since deep air and no backups were the norm. And I really dont think poorly of the divers who made those dives decades ago. There are better, safer, and readily available options these days.
:)
 
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