Reconsidering Deep Air?

[OTF]

The risk comparison between rebreather trimix and deep air (if those are your options) is an interesting conversation, and maybe a more valuable debate than deep air vs. OC trimix.

 

[Celt]

I've brought up some 4-ounce lead fishing sinkers from a shipwreck in 100 feet before.

But seriously, have you dove with a lot of recreational divers in 120 or 160 feet and been able to observe their performance/reaction?

If your experience is limited primarily to, "professionals and crazies" who routinely (work) and dive deep on air, your perspective might be skewed, because that sort of activity has a tendency to "weed out" the divers who are uncomfortable or ineffective at significant depths on air.

I still think your position would be strengthened if you acknowledged the differences between 30 and 60 meters.

I don’t know how narcosis or gas density affects other people, like they said on the video it depends on the individual. People should watch the video and ask themselves is there something to learn. Obviously there’s a difference of 30 metres between 30and 60. but where narcosis or density is concerned, for me there’s no difference. In fact some 30 metre dives can be more challenging than 60 metres depending on the conditions. I could count on one hand the amount of buddy dives I’ve done. My dives have been with a standby on the surface or solo.

 

[helodriver87]

I know a much smaller number who went CCR to avoid the dangers of Deep Air. 4 are dead and one came pretty close.

That's a really high incidence rate for a supposedly small group of personal acquaintances. If that's an accurate number, I'd be really curious to know the specifics (unit, training, sites, experience, etc). Seems to me that goes beyond the inherent risk increase of CCR diving and even bad luck.

 

[Wibble]

How do people forget dives, I’ve never forgotten one. How would a hypoxic mix reduce deco?

Sorry; edited. Meant hypERoxic mix

e.g. not 21% at 45m (140') but 25%. Has an impact on deco time, but not as much as using proper deco gasses.

 

[Wibble]

Couple of things about deeper air.

Had a 'pot dive' in a recompression chamber a few years back. Really interesting how it affects everyone. It was only to 40m/125' with a group of 8 divers. First thing I noticed was we were all giggling like a bunch of schoolgirls, quite odd. Were given some simple tasks to do on the bottom - add some numbers, name a river beginning M, nothing hard. When on the surface I couldn't read my writing and managed to get several wrong!

Basically it's like drinking more beer. A pint (half litre, 20 fluid oz...) for each 10 metres/30'. So we were giggling like we'd had 4 pints, probably about right. From my own experience of diving on deep air, getting to 50m/160' seems like you've drunk 6 pints; definitely getting proper squiffy. Worse than beer, it's becoming paranoid and you easily object/task fixated and loose your memory. Staring at the SPG and computer, but not reading it...

When we all jump into a car after having drunk, say 5 pints. Driving the car's easy because it's all unconscious competence or muscle memory. But we're absolutely not safe. We might get home, but we have a much higher chance of not getting home. One of the reasons why it's illegal; doesn't do to kill people because we're drunk.

With diving it's the same. We rely on our honed experience but narcosis does affect us. The worse part is it's unnoticed; we don't realise we're narked and potentially in peril.

Of course the more experienced people are far more aware of the issues, so it's possible to mitigate the affects to a point. Basically be slow and don't be brave.

 

[DiveClimbRide]

I think some of your points are valid, but they are diluted by the exaggerations above. Please share where in the world helium costs $300/cuft (~10.70/L)?

While not 300/cuf, helium here is around (usd) 6/cuf or (nzd) .30/l

 

[grantctobin]

While not 300/cuf, helium here is around (usd) 6/cuf or (nzd) .30/l

Yeah, have seem the same USD0.30/L in parts of the US Midwest (WI, MN), depending on the source. I don't disagree that it's expensive. Sinbad's "add two zeroes" is the delusion. Kia Ora.

 

[DiveClimbRide]

Perhaps he was thinking of the total gas bill. Doubling could add one zero but not two.

 

[CAPTAIN SINBAD]

I think some of your points are valid, but they are diluted by the exaggerations above. Please share where in the world helium costs $300/cuft (~10.70/L)?

Allow me to take you out of your economic bubble for a moment. The last time I checked, cost of Helium in Pakistan was not that different that what we have here in the US. Here is what that means for someone who is a local technical diver over there.

1 USD = 155 PKR.

Most people who dive in Pakistan are the young men and women who have just started a career and are making 100,000 PKR a month. That comes to 645 USD a month which is pretty decent salary for the local economy and buys you a decent life there but helium is prices are not part of that local economy. Imagine if you went to your LDS and each fill was half of your monthly salary then realistically as a technical diver you will have two options...

a) Stop technical diving
b) Dive deep air to a depth where your own sensibilities make it seem safe to you! (Whatever that may be.)

Which of the above would you choose?

I personally love GUE/UTD Standard gases but due to helium availability and costs, that style of diving has zero appeal in many parts of the world where people still dive. They would be more eager to take the TDI Extended Range course or PSAI Narcosis Management levels than Tech-1.

 

[CAPTAIN SINBAD]

That's a really high incidence rate for a supposedly small group of personal acquaintances. If that's an accurate number, I'd be really curious to know the specifics (unit, training, sites, experience, etc). Seems to me that goes beyond the inherent risk increase of CCR diving and even bad luck.

Three of those fatalities have been discussed here on these forums. The fourth one was an international incident that never made it on scubaboard. I do not know the units and the circumstances at the top of my head but we can browse through fatalities on scubaboard and those that could be attributed to deep air are less than those that can be attributed to CCR. Since there is more money to be made by the latter, weight of political correctness is also behind CCRs at this time.