Deep Air

[electric_diver]

Planned to roughly the same depths electric_diver considers "safe" on air. He toxed at 190ft on air after the bounce down to 250.
The Deco Stop

That dive was in the "insane deep air category" because PO2 > 1.6 for part of the dive. I do not consider 250 safe on air.

 

[Blackwood]

How one "feels" is an exceedingly poor indicator of personal performance.

Exactly right. Those times I've noticed the narc, I wasn't euphoric, or scared, or any of the other things they list as symptoms during BOW.

Rather, my attention went to hell. Single task? Sure. Two? Probably. Compounded task loading? Less likely.

 

[syntaxerrorsix]

How one "feels" is an exceedingly poor indicator of personal performance. You may "feel" just fine at whatever depth, but what matters is performance.

Back to our favorite narcosis analogy, drunk driving. The drunk person says things like "I'm fine, I've only had a few drinks! I feel fine to drive"...into a pole. Let's go ahead and dismiss "feeling" as a method of judging how narc'd one is.

Typically, with routine tasks that one performs regularly, there won't be too much loss in performance. Where it gets tricky is when a new situation is presented to you (some sort of emergency or problem underwater). Why stack the odds against you when a better alternative is available?

People have has real close calls and even lost their lives over this stuff. Its a foot on the banana peel that just isn't needed.

Then why aren't divers using helium at 60FSW if it's the equivalent of say 4 drinks? Are you going to justify "a little" intoxication? Or do we fall back on subjectivity?

 

[Blackwood]

There seems to be a slew of training agencies and divers that aren't diving helium and live. I won't concede that it's purely luck nor will I deny that deep divers benefit from helium. All I'm stating is that the depth a dive is considered "deep" on air should be defined more by high ppo2 more so than narcosis.

There's no doubt that oxtox is the most dangerous consideration, but I can't discount narcosis.

If you have one and only one (which may be your point given the topic: deep air), yes: go by PO2. But if you have access to blended gases, you have the ability to customize both oxygen and narcotic levels.

 

[syntaxerrorsix]

There's no doubt that oxtox is the most dangerous consideration, but I can't discount narcosis.

If you have one and only one gas choice, yes: go by PO2. But if you have access to blended gases, you have the ability to customize both.

I agree, but I won't sit out a dive to 150FSW because I don't have helium. Best available choice for the win.

 

[Rainer]

Of course diving deep air doesn't mean you'll instantly die. Duh. On most dives (whatever the gas), nothing goes wrong. Narcosis tends to rear its ugly head only in sideways situations. You can choose to stack the deck in your favor in such cases, or try to fight through the drunkenness. I personally don't care what you decide to do (really). I enjoy my own diving more with a clear head, recognize the obvious benefits to being clear headed if an emergency arises, and care enough about my family and friends to choose gases that up my chances of coming home if things don't go as normal. I dive for fun. Helium on deeper dives makes my diving more fun. It's that simple.

In any case, the fact you have no personal experience with trimix makes your comparisons a little suspect. Just saying.

There seems to be a slew of training agencies and divers that aren't diving helium and live. I won't concede that it's purely luck nor will I deny that deep divers benefit from helium. All I'm stating is that the depth a dive is considered "deep" on air should be defined more by high ppo2 more so than narcosis.

 

[syntaxerrorsix]

Of course diving deep air doesn't mean you'll instantly die. Duh. On most dives (whatever the gas), nothing goes wrong. Narcosis tends to rear its ugly head only in sideways situations. You can choose to stack the deck in your favor in such cases, or try to fight through the drunkenness. I personally don't care what you decide to do (really). I enjoy my own diving more with a clear head, recognize the obvious benefits to being clear headed if an emergency arises, and care enough about my family and friends to choose gases that up my chances of coming home if things don't go as normal. I dive for fun. Helium on deeper dives makes my diving more fun. It's that simple.

In any case, the fact you have no personal experience with trimix makes your comparisons a little suspect. Just saying.

And you pointing it out repeatedly is tiresome. I'm not hiding anything or discussing anything other than my current experience. Not to mention the fact that no cares to answer why folks don't use it on 60FSW dives if the benefits outweigh the risk associated with narcosis. Seems as if you are justifying use after you have already had a "6.53 pack 30END" worth of narcosis. Those first six drinks don't count right?

 

[Diver0001]

I certainly agree with what you've said and falling directly into the limited experience category I'll still express my thoughts on the matter and I've only based those thoughts on my own personal experiences to date. I find it amusing that you would assume because someone has not done a lot of "x" they they should not voice a differing opinion.

I'm not quite sure why you thought I was addressing you but I guess I struck a nerve nonetheless.

I guess you're right. The argument goes both ways. It's hard to argue in favour of it too unless you have the experience to back it up. Now that you mention it, that's certainly true.

I think I can safely say that I'm the last person who would want to stop you from voicing an opinion. I would hope, however, that if you're speaking theoretically that you're clear about it. I thought up to now that you were adamant about this because of your experience.

Based on my experience, for what it's worth, I would suggest that seeing PPO2 as the only relevant controlling factor is ... well ... naive. I know narcosis affects everyone differently but at the MOD for air, the narcosis can become pretty darned bad and a much bigger problem, if you ask me, than the O2 issues.

Something worth suggesting in order to clearly see what narcosis does to you is to take a chamber dive to about 30m/100ft. I was personally very surprised how narced I felt in the chamber at a depth that feels completely normal to me in the water. It was a real eye opener.

R..

 

[Rainer]

Where do you come up with this silly math? Are you drunk right now? So now each 10' of depth on air is the same as one drink? If that's the case, you'd be retarded to dive air to 150'!

100' is a mark some choose as a max END on the basis of personal experience *and* across subject testing and experience. It's a number that works well for most, while remaining conservative. I've dealt with "issues" at 60' and at 130' on air. The latter was noticeably less fun. For me, my family, and my teammates, I choose not to do 160' ENDs. That you do is fine.

And you pointing it out repeatedly is tiresome. I'm not hiding anything other than my current experience. Not to mention the fact that no cares to answer why folks don't use it on 60FSW dives if the benefits outweigh the risk associated with narcosis. Seems as if you are justifying use after you have already had a "6.53 pack 30END" worth of narcosis. Those first six drinks don't count right?

 

[PfcAJ]

Then why aren't divers using helium at 60FSW if it's the equivalent of say 4 drinks? Are you going to justify "a little" intoxication? Or do we fall back on subjectivity?

Because there is not enough (there's a little) impairment to affect most dive's ability to a degree that is potentially hazardous. The 100ft END limit is analogous to the .08 BAC. I can't ''feel'' when I have a .08, but I can gauge my body weight and number of drinks and come up with a reasonable estimate, just as you can gauge your depth and pN2. Regardless, feeling is a horrible indicator.

Another deep air issue I have is gas density and CO2 retention, decompression, and elevated ppo2s. So thats four separate issues, two of which are linked to narcosis (CO2 and N2). That's a lot of negatives just to save a few dollars.