Deep diving advice that goes against conventional thought?

[MXGratefulDiver]

It's a fairly well known that diving repeatedly and going slightly deeper on " build-up" dives can significantly lessen the effects of narcosis.

Actually it doesn't change the effects at all ... it simply helps you adapt to coping with them.

... Bob (Grateful Diver)

 

[danvolker]

A shot ( illustration by Jim Mimms) of the RB Johnson/Cory"n Chris at 285 max....one of our favorite Deep Air dives back in the day

 

[fsardone]

Hello everybody,
really liked this thread and I thought I could throw my 2 cents in.
I have been diving for 30+ years and the first 15 without even a certification, using own boat and own compressor. My father has an attitude similar (but a bit more safety conscious) to the spear fishing divers referred to the beginning and the origin of the topic.
He did not have stage tanks, he was strapping together 3 x12 litres tanks (about S80 for the metric challenged) and dived regularly to 75 metres and on occasions to 90m (excess of the 270'). So I grew up free diving spending whole summers free diving to 25M (75') and meeting with him in deco (solo diver .....). When I was finally 14, after reading all the theory of diving known to men in late '70, he allowed me to dive on a single tank we shared. I was hooked even before I dove the first time.

Air was all there was at that time (with the notable exception of a O2 rebreather that he dove to 20 metres 60' several times without dying). So I learned to dive to 50 meters on air well before becoming certified.

After several years I become certified I learned the rules (not past 40 on PADI AOWD, 1990s version) and made some more experience with a C-Card now. By the way the CMAS ( World Underwater Federation - Quality in diving) allows his 3star rec divers to dive on air at 1.4 PPo2 which is 56 meters. At this point in life I went to tech diving to overcome some limitations (no deco, I had been doing deco earlier and to go past the 40 meters limit and to learn something more).

The first tech course I did was a tech deep air. My deep air course was all about CO2, Nitrogen effects, O2 toxicity combined effects of the gasses and how to recognise your level of impairment and what mitigation action and recovery you could do to stay in control of your dive. The exam was to perform task, demonstrate skills in high narcotic environment and then debrief the dive to see if you actually were present to yourself. Inability to precisely debrief events would mean failure aven if the dive had been good.

This training served me good when a dive master decided to overexert himself at 43 meters (and attempted to have me doing the same) by swimming to fast he become seriously impaired. I recognised the symptoms I slowed down and when I caught up with him I was able to gently ascent to a shallower depth where he recovered (he had no recollection of the episode).

Now I am normoxic trimix (about to go for the hipoxic course) and my conclusion is like many others, that the mix (or the END I select in my mix) is driven by the tasks at hand and the environment. My current playground is the gulf of cagliari with several wrecks between 36 to 115 metres (multiply by 3 for rough feet) and I regularly dive in air up to the wreck of LT221 (I got stuck in it using air at 47 metres, alone in a complete silt out, but that is another story) and use mixes past this dept.

I am well adapted by repeated diving but this not withstanding diving Romagna (36 to 42 meters) we went with triox 27/15 because we had to do some penetration in tight spots and the bottom time was 45 (run 75) and so we padded our safety margin by decreasing EAD to 28.

Bottom line, Air can be dived to greater depts, it depends on the diver, the day, the task at hand. What is really necessary is learn our limits and respect them: they differ between divers and for a given diver from day to day. Learn to thumb a dive is an underestimated skill.

Happy diving

Fabio

 

[Akimbo]

…As I said in my first post on the topic, I am told that the effects of extreme narcosis are much different from what most of us have experienced.

In my conversations with Bret Gilliam, he described an effect at very great depths akin to blacking out...

A lot of people, including myself, have experienced symptoms “akin to blacking out” on mixed gases and on air. I have come to believe that blaming them on Narcosis is short-sighted — especially when you are below the 285'/2.0 PPO2 mark where lots of things happening and interacting.

Gas density and lung ventilation itself are significant issues. That is one reason that high blood CO2 is universally believed to be a significant component of Narcosis (directly biochemically or as a contributor). It is also the logic behind using Helium (which is about 1/7th as dense as Nitrogen).

You really notice the respiratory work load due to gas density of air at 250', especially in a chamber without all the distractions of dive gear and stress of being in the water. Lots of guys describe it “like breathing whipped cream”.

IGN (Inert Gas Narcosis) is called that because even Helium produces Narcotic symptoms in ranges starting about 10x deeper than air. Granted, Nitrogen isn’t an inert gas, but is believed to be biologically inert for this discussion.

…She and two buddies attempted a bounce dive on air to 300 feet, but when they hit 300 feet, she kept going and was not turned around by a pursuing buddy until she hit 400 feet. The common belief is that she was so thoroughly narced that she did not know what she was doing...

The key to this statement is “common belief”. Narcosis is far from the only factor at play below 300'.

It's a fairly well known that diving repeatedly and going slightly deeper on " build-up" dives can significantly lessen the effects of narcosis.

Actually it doesn't change the effects at all ... it simply helps you adapt to coping with them…

We don’t actually know that either. Lots of us believe it is much more complex than just coping.

I can offer dozens of examples that illustrates dramatic acclimatization effects of repeated near-term exposure to Narcosis. My first experience and probably most dramatic example was on a project in the early 1970s. It’s a long story but a couple of us needed to make up to four jumps a day on Scuba to the 160-180' range. There were no published tables for it in those days.

The Hyperbaric doc onboard calculated a schedule that alternated air and HeO2 (with lots of pure O2 at water stops and in the chamber). We started to notice that we couldn’t tell the difference between air and mixed gas jumps, which was obvious in the beginning. We were cold anyway and sound attenuation made the old Donald Duck voice test inconclusive on Scuba.

Later we were in sat and alternated between open-circuit air in the water and HeO2 in the chamber with the same result. It was not a matter of consciously coping or compensating, all perception of Narcosis was completely gone.

This was a real phenomenon to me so I brought it up to a salty old commercial diving super who looked at me with a blank stare and said “yeah, it happens all the time”. I later had the chance to see he wasn’t alone. This goes way beyond CO2, experience, and consciously compensating. Narcosis tolerance degrades to normal after the exposures stop and the acclimatization process repeats when exposures begins again.

That leads many of us to highly suspect that a biochemical adaptation occurs.

OK that is interesting, but probably has little impact on recreational Scuba divers (as opposed to what can be considered tech divers).
There aren’t many opportunities for recreational divers to make enough deep dives day after day for this phenomenon to be useful.

There is another “layer” of what some might call acclimatization that isn’t so transient. Your first deep dives are exciting and stressful. You don’t know how Narcosis will affect you and all those sea stories are in the back of your mind. Pile on gas management, decompression, and general fear of the unknown and you are stressed far above normal. That stress and hypersensitivity make actual and perceived Narcosis symptoms much worse.

With a little experience, most of these stressors don’t return, at least until you approach another depth threshold. You also develop coping mechanisms as you begin to recognize how Narcosis affects you — just as we develop coping mechanisms when we are tired at the end of the day.

 

[DCBC]

...I'm curious about the practical feasibility both of learning your narcosis threshold, and cultivating the ability to handle being narc.'d with a reasonable margin of safety.

As usual Richard, your points are thoughtful and well expressed. I believe that we all go through life in constant experiment. We learn to walk or ride a bicycle by falling, some of us become better drivers by getting into car accidents, or try different hobbies until we find-out that our favorite is SCUBA diving. We each live and learn, sometimes the experience can leads us to our demise and at other times enlightenment.

If you dive air at depth, you either learn your narcosis tolerance, or choose to disregard your safety. Understanding your narcosis tolerance can be best started by diving with a competent diver who understands their safe diving envelope. Undertake a slow descent and thumb the dive when you first feel the effects of IGN. Be aware, so you are not caught off-guard. This is something that's easily accomplished by a diver who's paying attention. One method is writing the 9 X tables on a slate as you slowly descend in stages, so your buddy can observe you. Once you have a base point, you can plan the next dive 10' shallower for a few minutes longer (still keeping aware through mental exercise). Needless to say, plan the dive so you are prepared to undertake the decompression required.

1.) People may not realize they're narc.'d until they try to do something challenging, or reflect on a dive after the fact (e.g.: why didn't being that deep the long alarm me?), or a dive buddy describes abnormal behavior to them they don't even recall. But at the time, they 'felt fine.'

I think that if this is the case, the diver's not taking the dive seriously and not prepared. If your diving to a depth where IGN can reasonably occur, it should be top of mind before you get wet.

2.) Narcosis susceptibility in an individual varies across different dives.

Yes, but the oncoming systems are not hidden from those who pay attention.

3.) If I understand correctly, narcosis on very deep dives can sometimes exacerbate pretty quickly once it becomes symptomatic.

Only to the unwary and unprepared.

4.) Most people don't have access to the testing equipment, testing and professional supervision that's guided DCBC's knowledge base.

I understand that this is the case and because of this I include an optional 100' Chamber dive in all my OW programs. A mandatory 130' Chamber Dive is incorporated into my Advanced Class. This of course is reflected in the cost of my program. Today most people seem to want training to be cheap & quick rather than comprehensive; go figure...

5.) ...So if we were equally physically susceptible to getting narc.'d, odds I'd get messed up may be much higher, because I'm more task-loaded even though we're doing the same thing.

Another example: A professional racing car driver and I are each driving identical cars on a wet road. As we go around a curve at the same speed, the back end of the vehicles start to slide. I believe that the other driver would be less perplexed getting the vehicle under control, where it might be a disastrous situation for me. The driver who is more experienced would likely know enough to slow down slightly before the slide occurred or would align the car beforehand to avoid the situation altogether. We would not likely drive our cars in the same way.

Similarly, I would not dive in the same way. I plan a deep-air dive considering all aspects of normal dive planning, but also consider hydration, calorie intake, rest, avoidance of alcohol and work load (CO2). More importantly, I don't approach the dive as a tourist, but as someone who is there to accomplish a job.

My level of concentration is high which improves my problem solving ability. Reaction time is mitigated through muscle memory. I enter the water expecting my physical and mental performance to deteriorate and actively monitor this by mental exercise until ascent.

I think most of the problem with Narcosis happens when Divers experiencing it are caught unaware, or when they feel the symptoms and welcome the experience (rather than seeing these as warning signals). Who doesn't want to feel great right?

Narcosis for me causes fear rather than euphoria. I suppose it's helpful in that my natural tendency is to want to get-out of the situation. It also causes my vision to narrow. These symptoms will happen at different depths on different days, but for me the symptoms are always the same. It's not that I can't feel euphoria (I have several times in a chamber), but I don't allow myself to go there in OW for some reason.

 

[jadairiii]

…. I enter the water expecting my physical and mental performance to deteriorate and actively monitor this by mental exercise until ascent.
….

Anyone considering diving Deep Air should read this a few times, consider the source (very experienced instructor) and ask yourself, “Why?”. Especially when the alternative is cheap and available. Cheap considering what your life is worth. Who would really want to start a diving knowing your “physical and mental performance to deteriorate”. Great way to plan a dive.

…. I think most of the problem with Narcosis happens when Divers experiencing it are caught unaware, or when they feel the symptoms and welcome the experience (rather than seeing these as warning signals). Who doesn't want to feel great right?
….

No, the issues arise when, faced with a problem, SAC rate increases, increasing CO2, compounding narcosis along with spiking PPO2’s. A perfect storm. Narcosis by itself is never really the problem, but few think it through.

…. Today most people seem to want training to be cheap & quick rather than comprehensive; go figure...….

Go figure, people rip GUE training because it takes so long, is so expensive and “overly” comprehensive. Then they pick “cheap and quick”

 

[DCBC]

Actually it doesn't change the effects at all ... it simply helps you adapt to coping with them.

Actually there's not enough known about IGN to state much categorical. The reduction of performance task improvement times are largely attributed to experience in performing the function (muscle memory). Although they may be attributed to some degree to repeated exposure (in a similar way to alcohol). To my knowledge, there are no studies that have proven reduced reaction times by acclimatizing the same individual. This seems to be an area which plagues everyone equally.

Even when aware of a problem, people attempt to solve it in different ways. Some are incapable of addressing the situation at all (even without Narcosis being a factor). An emergency event can cause some to panic, while others can address the problem quickly. Attention to the issue is also a factor. A Librarian may take longer to react to severe bleeding than an Emergency Nurse or Physician would. Reaction time (and reflexes), correct assessment and action (problem solving) are dependent upon a person's attentiveness, experience and abilities. Narcosis slows these processes down, but is too often used as an excuse for poor performance.

In diving fatalities it's difficult to attribute Narcosis as a major factor and few situations has this been the case (causing blackout for example). This is especially true if Narcosis starts to affect performance and is ignored by the Diver (you can stop descent and ascend anytime you want), so a degree of carelessness on the Diver's part is apparent.

Usually something goes wrong and the diver is unable to correct the problem (or compounds it). To say that without Narcosis the Diver could adequately address the situation (without panic) and make the correct decision is not something that's often apparent. Narcosis is more often slated as a contributory factor to the eventual cause of death.

---------- Post added March 17th, 2014 at 09:53 AM ----------

Anyone considering diving Deep Air should read this a few times, consider the source (very experienced instructor) and ask yourself, “Why?”. Especially when the alternative is cheap and available. Cheap considering what your life is worth. Who would really want to start a diving knowing your “physical and mental performance to deteriorate”.

I learned to dive Deep-air because Trimix wasn't available anywhere at that time. I was a diver that wasn't content with diving above 50 FSW (the area where IGN isn't a factor). I dive Trimix or HeO2 when the dive calls for it and it's available. I've dove in a number of locations world-wide where it hasn't been.

The alternative is not within the financial reach of everyone; nor is it available everywhere. There are people who don't want to use Trimix.

I do however encourage you to use Trimix on all dives past 50 FSW. Our safe diving envelopes on Air are obviously very different.

Great way to plan a dive.

Diving is not inherently without risk. I think that risk assessment is a requirement in any good dive plan.

We each accept the risks we feel comfortable with. Some feel they can dictate their values to others. Personally, I believe this to be arrogant.

 

[jadairiii]

.....
The alternative is not within the financial reach of everyone; ....

Deep Scuba diving seems to be the only sport that uses this copout for why divers would use less than optimal equipment, training or procedures. You would not see that comment with regards to auto racing, mountain climbing, parachuting, or any other endeavor that has higher element of risk.

.....
…. I enter the water expecting my physical and mental performance to deteriorate ....

Then again, I doubt you would see anyone actually say that either when they could simply breath a gas to avoid it.

 

[DCBC]

...You would not see that comment with regards to auto racing, mountain climbing, parachuting, or any other endeavor that has higher element of risk.

Sure you would. In climbing some people like: sieging over alpine style; they climb 'strictly on' or choose their own path, employ equipment in ways in-which they weren't designed to be used (or not). Climbers have different goals and choose between traditional, sport, or solo. Some are free climbers, while others prefer aids.

When climbing any mountain, the most important aspect is risk assessment and constant re-evaluation. The equipment you take is dependent upon the technique you choose to employ, and that which is reasonably dictated by the climb itself. Experience, fitness, support, time, weather and style all mitigate these choices.

One of the rules of climbing etiquette is not to comment on the equipment choices of others. You're free to select what you and/or your team deem necessary and refrain from commenting on matters that don't concern you. Just like diving...

 

[100days-a-year]

10 to 20 grand extra a year for me to dive mix keeping my EAD to 100' not to mention the logistics of have 3-4 divers worth of He on the boat.I'm thinking 2-3 Ts each for a typical trip.Not likely to happen.Nor have I seen any evidence of anyone improving in ability on gas at the depths we dive.

In a world where I win the lottery I will dive 16/25 or so all day long for a different reason,increased PON and PO2 are likely complicit in necrosis in joints.