Deep Air Dives In Tech Classes

[Patoux01]

I don't see any risk in eating pasta, unless they were really bad, so that analogy doesn't suit. If he had said "if you can't afford a redundant setup, why do you dive to 60m?", would that still have hurt your feelings? I certainly hope not. There's no actual need to go that deep, there's plenty of safe dives to be made without more gear or training.

 

[Centrals]

I have been to many places where nitrox is NOT available let alone helium.
Do I care about comment like "if you can't afford helium......."? I don't give a toss.

 

[northernone]

I don't see any risk in eating pasta, unless they were really bad, so that analogy doesn't suit. If he had said "if you can't afford a redundant setup, why do you dive to 60m?", would that still have hurt your feelings? I certainly hope not. There's no actual need to go that deep, there's plenty of safe dives to be made without more gear or training.

In the context of this thread... (Deepish air diving for tec training taught the major agencies) The gas fill is a tiny portion of the price involved anywhere I've seen the optional "lite trimix" add-on. I can't imagine the agencies who teach narcosis management and want their divers to experience 40m on air are doing it to cut costs for their instructors and certainly not for the students. The training manuals are quite clear on the learning objectives. I'm not sure why this is mysterious to some. Perhaps they disagree?

Perhaps AJ will drop in again, I read it as he sees no advantage to training on air in the context of "deep" certification courses diving (in favor of trimix I assume). In that case the only advantage would be money saved. No learning benefits or value added from his perspective. Did I read this correctly?

Anyone who used the "If you can't afford x you have no business doing y" has generally been an ass in my experience. Subsequently it regularly turns out X is optional and they had very few valid reasons besides being elite about it (or promoting what they sell)... I'm fairly sensitive to it as I was always on the tightest budget in any of sport/hobby peers. I'm not sure that's what was intended to be communicated in this case.

Cameron

 

[RainPilot]

I see your point, but I mostly disagree. The greater point is that financial resources do matter, but telling someone "you're too poor to ______" is, at its core, elitist.

Certainly, if someone is doing something blatantly unsafe--such as racing motorcycles without any safety gear whatsoever or, as you pointed out, cave diving without training--then it's ethically correct to step in and say "dude...don't do that."

However, what we're discussing here doesn't push those extremes. Let's say that our motorcycle racer has secondhand riding gear, or a previous-generation crash helmet. Modern protective clothing would make our hypothetical motorcyclist much safer, but unless we're discussing elite racing or particularly dangerous stunt riding, then older gear will be entirely adequate, and telling the rider to come back when he's rich enough to afford top-of-the-line equipment is neither necessary nor desirable.

With the analogy of cave diving, there's a big difference between saying, "you really should get cave training before attempting that dive" and saying, "you can't afford cave training, so go away."

I'm sensitive on this subject because, back when I was a relatively new diver and working as a retail-wage-slave, I was a member of a scuba club that held its meetings over dinner, at a spaghetti restaurant that charged us a modest ten bucks or so per head. One member floated the idea of changing the meeting site to another restaurant, one that was much more expensive, and I ventured the opinion that changing venues wasn't the best idea because some of us (such as myself) were on budgets. The member came back with "Well, if you can't afford this, why are you even diving?"

I can totally see that point of view. @PfcAJ will not take great exception to me saying that he is not the most....diplomatic...member on here some days, but I also totally see his point. Where analogies like these fall flat however is that we are not talking about diving an older model computer or lovingly refurbished old regs etc.

If someone wants to do a 300' dive on air and the reason they give is that they cannot afford helium, they should not be doing those dives. There is a cost of entry/progression into the sport, thankfully it can be pretty low but... once you start getting to technical diving there are some things you could skimp on, but your breathing gas is not one of them.

It's like people overdiving scrubbers because they want to save 20$ on adsorbent and then they cost their families a lot more in funeral bills. That's if people like @PfcAJ and @kensuf have managed to go and recover them, using gas and sorb that they have paid for themselves.

 

[seeker242]

I see your point, but I mostly disagree. The greater point is that financial resources do matter, but telling someone "you're too poor to ______" is, at its core, elitist.

Certainly, if someone is doing something blatantly unsafe

The discrepancy here is that you have a different definition of what is considered "blatantly unsafe". I'm pretty sure he, and others, considers deep air to = blatantly unsafe. Doing something that is blatantly unsafe, because you can't afford to do it a safe way = absolutely stupid.

 

[Scott]

On Thursday I leave on vacation with a group of divers. I recently found out one of the guides is tech certified and inquired about making a couple dives during our stay.
After some discussions I opted out, mostly because of available gas choices.
I’ve done 55m on air, my initial tec class was on air. I’ll teach a class on air or best EAN for the dive.
Would I prefer to do those with He, yes.
The resort I was speaking with doesn’t have He so all dives would be air. What was the deal breaker was deco gas was limited to 32%. They had recently lost a large majority of their tech equipment to the sea along with a boat.
Everyone makes their own choices.

 

[Bob DBF]

Deep is a rather nebulous measurement, may be people should chime in on where deep starts, and should end. PADI, from what I recall, starts deep past 60' and ends at 130', at the recreational limit, but with their tech training someone will have to inform me of their upper limit.

The point is divers decide what their range is on the gas they are using. Some use trimix at 100', others wait until the recreational limit, some beyond. For standardization why not use trimix for every dive? Somehow it all gets back to the relative usefulness compared to the cost for everyone.

In my case, I began to dive air deep because there was no alternative. By the time there was an alternative and training, I was past the dives I would use trimix. Getting old is a pita and I limit my excursions more than in the past so I see no need to trade a proven method for one that will take time and money and probably never be used outside of training.


Bob

 

[RayfromTX]

The motorcycle racing analogy is not accurate.

If you don't wear adequate safety gear you will suffer in an accident but it won't cause the accident. If you make a mistake because you are narced...........

 

[MaxBottomtime]

I think a large part of the problem is training. Some agencies drill into their students that anyone not diving their way is stupid and will die for sure if they dive deep air. These students then get on the internet and proclaim that everyone who went past some magic number, 100', 130'...either died or barely escaped death. The fact is that people have been diving deep air for decades and many still are. Additional risks mean more risk management, not certain death.

 

[GJC]

There is no way to "adapt" or gain tolerance for the extreme narcosis with progressively deeper dives following the PSAI Deep Air Course Levels 1 thru 6 (30m; 40m; 46m; 55m; 61m and 73m). Any work or exertion at these depths -66m and deeper- resulting in a heavy labored increased breathing rate (tachypnea and/or dyspnea) will immediately initiate the spiraling vicious cycle of CO2 retention/poisoning into Hypercapnic stupor and unconsciousness, along with the increased risk of Oxygen Toxicity Syndrome & Convulsions.

One additional compounding factor to consider as well is the water temperature:
Cold Shock Response lasts for only about a minute after entering the water and refers to the effect that cold water has on your breathing. Initially, there is an automatic gasp reflex in response to rapid skin cooling. . . [Usually not a severe issue jumping in cold water in a drysuit with appropriate insulating undergarments]

A second component of the Cold Shock Response involves hyperventilation. Like the gasp reflex, this is a natural reaction to the cold. Although this physiological response will subside, panic can cause a psychological continuance of hyperventilation. Prolonged hyperventilation can lead to CO2 retention, Hypercapnia and additive effects of Nitrogen Narcosis at deep depths, so the key thing is to concentrate on controlling your breathing. . .

However even with a Scooter/DPV providing mobility to reach 90msw and then only floating relaxed horizontally in neutral buoyancy, just the increased work-of-breathing (WOB) due to the high gas density is potentially enough by itself to elicit CO2 retention along with compounding the anesthetic effects of extreme Nitrogen Narcosis.

27 Aug 2017.
Oil Rig Eureka Bounce Dive, Solo;
1min Bottom Time @ 90msw depth (10ATA);
The ppO2 atm of Nitrox 21% (Air) @ 10ATA: 2.1 bar;
Gas Density @ 10ATA: 12g/L (approx 10x more dense WOB than Air at surface);

Descent Rate (via DPV/Scooter): 30m/min;
SPG reading at Start of descent (10m depth): 180bar;
Depth Consumption Rate (Open Circuit) @ 10ATA: 20bar/min;
Amount of Gas consumed & used to inflate Wing & Drysuit on 3min descent to 10ATA: 40bar;
SPG reading at elapsed dive time 4min (3min descent plus 1min BT @ 10ATA): 120bar. In other words, 60bar total was used in 4min;

Ascent Rate: 10m/min from 90msw to 15msw;
Deco Time Required (on Air): 1min @9msw; 3min @6msw and 7min @3msw;
Total Time of Dive: 30min;
SPG at End/Surface, remaining Air: 40 bar;

Single Tank Aluminium 13L with 210 bar initial fill;
Apeks XTX100 Regulator;
Dive Xtras X-Scooter Sierra, 150m depth rating;
Water temperature at depth: 14°C.

The scary part other than the black abyss outside my primary light source, was the temptation to just drift off with the anesthesia of the extreme N2 Narcosis -and that was within one minute at 90msw with no physical activity, but with increasing work-of-breathing trying to expel metabolic CO2 even in a non-exertion, "resting" state floating neutrally buoyant. In other words, even though completely relaxed with deliberately slow and deep inhalation & exhalation respiratory cycles, I couldn't get rid of Carbon Dioxide fast enough because of the higher Air density at 10ATA Pressure -it just became too hard to breathe efficiently anymore without going into prompt Hypercapnia.

Good reference article on Gas Density, and an implied explanation on why the Recreational Depth Limit on Air just happens to be around 40msw:
Advanced Knowledge Series: The Gas Density Conundrum | Dive Magazine

You mentioned prolonged hyperveventilation can lead to CO2 retention.

I was not aware this was possible. I thought hyperventilation always resulted in low CO2.

Can you explain how this may occur?