Before my UTD days, I had approached PSAI for their Narcosis Management courses. They were the only agency training divers in Narcosis Management in various depth increments like
Level 1 - 100'
Level 2 - 130'
Level 3 - 150'
Level 4 - 180'
Level 5 - 200'
I asked PSAI how do you "manage" Narcosis. The reply that I got was as follows. Areas worthy of attention have been underlined (by me.)
I may be able to help explain the Narcosis Management course. Generally, students begin at Level I (100fsw/30m). It’s not that you are incapable of diving at that depth. Rather, it’s just the opposite. After substantial classroom work you will perform dives at Level I for you to establish your baseline performance. From here, with each increasing depth level, you can objectively assess your performance at depth. If you do enough levels, you will reach a depth in which you will experience broad failures in performing the assigned dive tasks. You will then “learn” your practical air-depth limits.
These dive tasks are practical in nature. Primarily they are DATA, which is Depth, remaining Air, dive Time, and general dive Awareness (dive plan, buddy awareness, potential water hazards, etc.).
It may help to know that Inert Gas Narcosis is nothing more than a form anesthesia. Forget all the other nonsense. If you go deep enough, you will simply go to sleep and drown. Some do not handle even mild to moderate (typical recreational depths) narcosis-anesthesia very well and will show loss of concentration, poor judgement, and act in seemingly illogical ways. This deterioration in mental capacity can become dangerous, long before you would “fall asleep” at great depth.
Each individual has his own unique limitations. The 130fsw/40m air limit can be relatively safe with proper training for many divers, but this certainly is not the case for all divers. Obviously some, but not many, have had success in diving much deeper. Increasingly, agencies are encouraging lesser depths for recreational limits in part due to public’s lack of interest in proper training and in refusing to build depth experience incrementally.
Now this is important, you cannot teach somebody to dive to some arbitrary depth. Their limits are fairly fixed. If somebody is already having problems at 130fsw/40m, he is never going to “learn” to dive to 180fws/55m. In our experience, continuous accommodation training (developing tolerance) very seldom nets more than about 1 atm. (30 fsw/9m) in working depth, if even that much! You pretty much are what you are AND do not change much, if any.
We DO NOT recommend or encourage anybody to perform dives that are beyond the limits of their formal depth training and certification.
The ideas expressed were not a huge departure from my own views. I had seen some people act very slow even at 110 feet while others would do very complex tasks like operating DSLR camera with strobes, manipulating through the menu to select aperture, shutter speed, strobe power and putting it all in synch at 150' without too much challenge.
Now if we are going to standardize a gas for various depth ranges, are we going to standardize based on the guy who is operating DSLR at 150' or are we going to use the guy who is losing his mind at 110? The funniest thing is that the guy who loses his mind at 110 feet may not be convinced that he is acting slow at depth. This means that you really can not be a judge of your own self. This is why GUE/UTD standard gases make sense because if you add one irrational person into a dive team then the whole team gets compromised. Similarly, sticking to GUE/UTD standard gases meant that almost everyone is surfacing alive no matter where they are on their personal narcosis tolerance level.
I had the opportunity to discuss Narcosis very briefly with John Chatterton. It was never my impression that he was suggesting constant exposure to Narcosis as a way of developing tolerance. He was critical of standardizing gases due to a totally different reason. To him, making conservative rules that would apply to a vast population was often a substitute for more in depth knowledge. He wanted all his students to understand various components that factor into narcosis and none of those would be necessary if the technical diving population was being trained to switch to Helium at the lowest common denominator. He was of the opinion that WOB (Work of breathing) has a lot to do with how Narced you would be and managing WOB was one of the fundamental aspects of Narcosis management in his view. So there was a skill or technique to diving deep while maintaining brain function and it was not repeated and constant exposure.
He was coming from the background of commercial diving and commercial divers often dive solo. Knowing ones own limits and how one would respond to Narcosis on an individual level was of greater importance than throwing away that knowledge to become part of a "team." He mentions that he is comfortable diving to 200' on air as long as the dive permits him control of all factors that effect narcosis. He says that he has used Helium shallower than 200' when dive was complex or factors effecting narcosis were outside his control etc but there was no "one size fits all dives" approach in his mindset. Instead a fundamental part of the training of a technical diver in his view was to understand what would work, where.
So yes for what it is worth, this was a huge departure from my own UTD/DIR mindset.
