Deep Air

[Gilldiver]

I wouldn't go as far as to say that the test is meaningless. It does identify those individuals who are highly reactive to oxygen. The U.S. Navy / Coast Guard discontinued the testing because they claimed it did not have "highly reliable results." Hyperbaric oxygen tolerance testing is still a requirement for all diving candidates in Canada and other allied countries and is still used by several areas of the commercial diving sector.

Testing results for some reason are more accurate in a wet chamber, but usually performed "dry" for safety reasons. Most tests are given in a hyperbaric chamber in two parts, a 60 FSW exposure (as you mentioned) for 60 minutes on O2 and 165 FSW exposure on air. ADCI training standards do not require O2 tolerance testing for commercial diving, however it's a requirement of some schools, contractors and insurance companies.

I do remember one old master diver who would take the new guys down to 60 on 100% and PT them till they toxed. It was not so much of a test as a warning to those guys about how quickly it can occure if you are not watching and working hard.

 

[boomx5]

Yesterday, while breathing Triox 25/25 at Dutch Springs, I had the chance to contemplate helium vs. air diving.

Recently, I had made 2 dives on the Jodrey with Trimix 18/48 (final analysis shooting for 18/45) to 161 feet. The week prior, I was diving Nitrox 32 at Dutch Springs filming a GUE Fundies class with a max depth of 30 feet. The week after the Jodrey, I was diving to 80 feet in Bermuda on air, and yesterday, I dove Triox 25/25 at Dutch Springs teaching class to 90 feet.

Of these, the worst dives were dive 1 & 2 on the Trimix 18/45 to the Jodrey and yesterday's dive on Triox 25/25. Yesterday, I hit cold water after a week in Bermuda and was back in a drysuit, doubles, hood, argon bottle, stage, etc., so I just wasn't feeling into the groove despite the fact that mix helped me notice a few details about "my office" that I hadn't noticed before on the deeper sites. But, I'll share what I learned about deep diving from my recent dives based on experience.


The problem with diving the Jodrey was that on the first day, we had a team of 3 in which not all divers had been diving together prior to that dive. Added to which, we decided to take Gavin scooters. One diver teaches Gavins, the other just took his course, and the third (me) has only used a Gavin on 3 dives. I expressed my aversion to making a dive with an unpracticed team and with not having the ability to play with a Gavin the day before to get settled into the "feel" of that model scooter. But, the third guy in the team was willing to pay for the trimix if we scootered.

Note: Notice that this is much like deciding to "dial a high" in trimix diving when cost of helium dictates how impaired you will be regarding an END due to what mix you find acceptable. While we may have been on the best standard gas for a 160 foot dive, we decided to operate with the additional risk and complexity of possibly having to handle emergencies with scooters. This may not have been the wisest decision for inexperienced Gavin pilots who never worked together as a team prior to that dive.

A skilled team used to working together, and with many hours on the Gavin scooters, probably would have been safer and performed better at 160 feet on air or enriched air than we did on trimix that day. The gas certainly helped us. The selected handicaps didn't help us. While in shallow water, I made the call to thumb the dive based on scooters and the team decided to ditch the scooters. After the dive, the third guy in the team that wanted to scooter was happy that I made that call. Our ascent together was sloppy due to team communication. We also didn't have a solid deco plan so the team captain called it and we played followed the leader.

The second day, we still had good gas in our favor. We then had one dive together that helped assess the team's strengths and weaknesses. We left the scooters, came up with a better deco gas plan, but we took on the handicap of diving with a group of Canadian friends who arrived in their RIB. We had three teams of 3, 2 and 2 going to exactly the same spot on the wreck. It was the DIR version of a recreational wreck diving cluster. 3 cameras - video and still - blinding subjects with strobes and video lights, all divers looking identical, posing, smiling, profiling, losing buddy awareness, tight teams breaking into temporary or loose teams, and teams reforming. The good news was that we had good gas, standardized procedures, and the same exact training. Should something have gone wrong, we had the ability to fix it with anyone from any team. However, the lack of constant vigilant awareness could have placed a team member at risk of falling through the cracks of that awareness. More than once I truly believed my buddy was still right by my side only to discover it wasn't my buddy and that my buddy needed to be located. I decided to just stop my part in the madness and become the lifeguard by just staying put in one spot on the wreck so my two buddies could constantly reference me during filming and sight-seeing and I could watch everyone. The good part was that our deco went perfectly and we acted and moved as a team in textbook fashion. Until 20 feet, where we didn't have a plan due to leaving a second gas switch option open. That resulted in a board meeting on wetnotes.

Lesson: While decreased awareness and attention to safety is often blamed on air and narcosis, the lack of awareness caused by too many "same-same" divers with too many distractions such as the sort that occurs during filming, can create the same if not more dangerous, lapses in attention and reaction time.

Also, while those of us with training and experience with calculating deco on the fly, may elect to do so, much confusion and stress can be removed from a dive with a solid plan. One concern I have about new trimix divers is that they may believe they are bullet-proof on trimix and a moving target on nitrox and sitting ducks on air. It should be understood that the use of trimix does not remove a diver's need to place the same emphasis on dive planning and team familiarity that has been practiced by deep air divers to increase their safety when diving somewhat impaired. Two drunks with a plan may operate better than two sober people with a blurry strategy.


Conclusion: There is far more to safety when deep diving than just "narcosis management." While trimix is definitely an excellent tool to add to the equation of the planning and execution of any dive, it is not a magic formula for safety and performance. Divers must assess all the variables and parameters on dives to determine which ones will present the greatest problems for safety. Whether oxygen partial pressures, END's, decompression obligations, thermal issues, team experience, etc., each one becomes a vital figure in accident prevention and dive success. We stack the odds in our favor by balancing all potential threats, complications, standard procedures, benefits, and ad-libs on the scale of prudence.

That's a great and transparent report Trace...thanks for sharing! We had a dive a couple months ago where we had several planned tasks. The dive was to be a max depth of 250' and we had to fix some augers, lay bottles and check a line. The gas we were on was 15/55 (14/58...they are hardly ever exact). Once we got to about 120' we noticed the water getting real cold and at max depth it was 34 degrees. Between the cold, an unfamilier site scooter trigger sticking on at 250' and all the task loading I was more imparied than I think I've ever been on a dive. Once we got back to some warmer water and made our gas switch my buddy and I looked at each other like, "what was that all about?" It was so noticable that we went back and re-analyzed our gas that night thinking there may have been an issue with either the analyzer or bad gas. I remember reading George Irvine when he said being cold will make a person dumber than narcosis...and I certainly understand that now. A couple of weeks later we did a similar dive to 265' with about the same mix, but the water was way warmer and we had none of the task loading and my head was clear as a bell and it was a very relaxed dive.

 

[Trace Malinowski]

That's a great and transparent report Trace...thanks for sharing! We had a dive a couple months ago where we had several planned tasks. The dive was to be a max depth of 250' and we had to fix some augers, lay bottles and check a line. The gas we were on was 15/55 (14/58...they are hardly ever exact). Once we got to about 120' we noticed the water getting real cold and at max depth it was 34 degrees. Between the cold, an unfamilier site scooter trigger sticking on at 250' and all the task loading I was more imparied than I think I've ever been on a dive. Once we got back to some warmer water and made our gas switch my buddy and I looked at each other like, "what was that all about?" It was so noticable that we went back and re-analyzed our gas that night thinking there may have been an issue with either the analyzer or bad gas. I remember reading George Irvine when he said being cold will make a person dumber than narcosis...and I certainly understand that now. A couple of weeks later we did a similar dive to 265' with about the same mix, but the water was way warmer and we had none of the task loading and my head was clear as a bell and it was a very relaxed dive.

Apparently, the "transparency" of the posts are a little hazy since my post generated a few phone calls to my dive buddy.

First, I want to clarify that the issues that I posted about were "nuances" of the dives. The dives were all quite safe. In fact, the dives were far safer than most dives on a training platform at Dutch Springs to 30 feet. Were they fun? You bet!

My points were to draw comparisons between trimix dives and air dives and to discover holes in the "trimix" mantra that makes trimix seem like the "magic formula" for safety and success. I am a firm believer in trimix, but I viewed these dives under the scrutiny of a tech instructor debriefing a class and not as one of the divers involved.

I tend to observe students and dives against the "Utopian" picture that we try to create in technical classes and look at dives as holistically as the arenas in which they are being conducted. As an educator and philosopher, I try to learn as much as I can about diving from every dive and pass subtle lessons along to my students and to others such as here on this board.

As GcBryan often says, he hears much of the mantra, but he is always trying to find the true knowledge when someone posts mantra. On boards, we find a large population of relative beginner divers who have been exceptionally trained, but sometimes lack the knowledge of the giants upon whose shoulders we stand today. While their postings, education and training is often very sound, what sometimes is lacking is the experience or the ability to appreciate viewpoints and experiences outside the realm of what they have been taught. It is often my intent, to open up debate and to create thought-provoking posts, to broaden the horizons of others and even myself as the ideas formulate and are shared. Isn't that why we are here? People ask questions and provide reasons which get us thinking and we look into our own diving experiences to find essential lessons to grow and become better.

I have the experience to look at what goes on underwater as an instructor, as a professional lifeguard, as a diver, and as the perpetual student of the sport. The dives in these posts were quite solid, but even on solid dives, good instructors can find ways to improve performance. As a 27 year veteran of the sport, I also try to look for stories in the "ordinary" dives that are lessons learned rather than the epic adventures. It's easy to learn a lesson when you nearly die at 250 feet on air in a cave, but it is what we learn during the ordinary dives that helps us not end up having an epic battle for survival. I also try to share the subtleties of how small additions such as an unfamiliar scooter, may make an experienced diver uncomfortable. My level of uncomfortable is that on any given day on any given dive, I'm usually perfectly dialed-in and feel like I'm in my favorite pair of jeans with my drink on and my snack on watching the NFL. With the Gavin, it was like having the drink on and the snack on, but having a new remote control.

As a leader, I try to lead by example. If a student thinks I'm bullet-proof, he'll most likely try to be bullet-proof too. If I demonstrate that I'm not bullet-proof, that student may draw some resolve and some courage to speak up or thumb it when he's not feeling the groove. Sometimes, not feeling the groove is simply not feeling like you can park it on a dime and not scull a fin. You may be annoyed that you need to scull a bit to maintain stability. That was how I felt at Dutch coming back. I kept asking myself, Why are you moving your feet? Since it took me a few minutes to get that sorted, I wasn't feeling it. Sometimes, not feeling the groove might be a really bad feeling about something ... a tool, a plan, a teammate, the environment ... something, but sometimes you have that gut feeling or that instinct. I often listen to mine.

To clarify, none of these dives was a cluster-f or dangerous. What I meant by "cluster" was that the wreck was busy with all seven of us. Had everyone had their name on the cylinders, it would have been easier to maintain awareness, but that wasn't "dangerous" per se. Everyone on that dive has a slightly different perspective, which brings me back to the intent of my post. To further illustrate, some people reading about that might create an image of a bunch of idiots lacking awareness diving dangerously in a dive that was lucky to not become a cluster-f with an accident. FAR FROM REALITY. Getting back on topic, if two divers spoke of making a dive using air to that depth, many would think they were idiots, narced out of their minds, and unable to come to one another's rescue. In reality, their dive and their awareness might be much better than someone would think - not having been there. Many of the divers screaming that air is a death gas have never been beyond recreational depths on air, yet they have created an image of it being dangerous - much the same way that some people may have created of the dives I mentioned.

My ultimate point is that deep diving decisions are holistic and the gases used are just part of that equation.

Hope that stops the phone from ringing, buddy.

 

[DCBC]

Thanks for the excellent post Trace. It seems that too many divers today plan their more advanced diver training by way of minimum requirements. A couple of weeks back one OP explained how he was taking a couple of weeks off and going through 4 or 5 technical training courses and would soon be diving trimix at 300'.

As I've said in the past, people want it all and they want it now. It would seem that the day of "going deep through experience" is over. As you have accurately pointed out trimix may addresses nitrogen narcosis and oxtox; which is tremendously beneficial if the dive is at 300', but that's not all a diver needs to be concerned about.

Personally, I'd like to see all divers diving past recreational diving limits (130') to have a minimum of 500 hours underwater, with a documented track record of progressive experience in decompression diving. A person can understand the theory, but experience is the greatest teacher.

 

[Diver0001]

Personally, I'd like to see all divers diving past recreational diving limits (130') to have a minimum of 500 hours underwater, with a documented track record of progressive experience in decompression diving. A person can understand the theory, but experience is the greatest teacher.

You want them to have a track record of progressive experience with deco diving and dives deeper than 130' before they get the training.... Or did I just not understand you?

It's a bit of a catch 22 isn't it, Wayne? If you want them to have experience before they have the training then we can't also worry about them doing the dives without any training....

Going the other way, if we train them before they have any experience, then how will we know beforehand that they can do it?

If I understand what you just said then I think you may be caught up in circular reasoning here. Training is something we do, in my mind BECAUSE we have no experience. Experience is something we get after training. You can give them some relevant experience in the training but that's it. At some point you have to cut them loose and let them get experience by diving..... It's the only really reasonable option we have, right?

R..

 

[Rhone Man]

It is a bit of a Catch-22, enough experience to get the training, or enough training to get the experience?

Terry de Wolf died on the Andrea Doria with only a handful of dives (am I misremembering? I think it was 100). Dave Shaw died at some unfathomable depth on only his 333rd dive. Would they have lived if they had been forced to log 500 or 1,000 dives before starting technical training? Maybe, maybe not.

But there is clearly much better training more readily available these days than ever before. No one should run before they can walk, but I think people are better equipped to learn to run more quickly than in the old days. And that is a good thing, so long as that freedom is utilised responsibly. Gary Gentile logged about 2,000 decompression dives before he started experimenting with diving deep on Helium mixes. I don't think the rest of us need wait so long.

Two of my favourite P.J. O'Rourke quotes are:

"One of the annoying things about believing in free will and individual responsibility is the difficulty of finding somebody to blame your problems on. And when you do find somebody, it's remarkable how often his picture turns up on your driver's license. "

"There is only one basic human right, the right to do as you damn well please. And with it comes the only basic human duty, the duty to take the consequences."

 

[DCBC]

You want them to have a track record of progressive experience with deco diving and dives deeper than 130' before they get the training.... Or did I just not understand you?

It's a bit of a catch 22 isn't it, Wayne? If you want them to have experience before they have the training then we can't also worry about them doing the dives without any training....

Going the other way, if we train them before they have any experience, then how will we know beforehand that they can do it?

If I understand what you just said then I think you may be caught up in circular reasoning here. Training is something we do, in my mind BECAUSE we have no experience. Experience is something we get after training. You can give them some relevant experience in the training but that's it. At some point you have to cut them loose and let them get experience by diving..... It's the only really reasonable option we have, right?

The recreational agencies suggest a maximum depth for sport diving to be 130'. For clarification, before a diver dives deeper than this, I'd like to see them develop substantial experience above this level. I would further suggest for them to gain further instruction in decompression procedures before taking trimix courses.

I agree that we train before getting experience. We don't start school however, at the university level. We crawl, walk and then run.

Because a diver completes a course of instruction in air and gets some experience at shallow depths, he shouldn't be diving trimix two weeks later at 300' imo.

Regards,

Wayne

 

[Herk_Man]

I often dive to around 160-185 on air for around 12-15 minutes. I generally don't sense that I am very narced, but I am definetly aware of the depth and try to be extra careful, double check my decisons etc.

Last time out, I was solo on a wreck at around 180 ft and shot a relatively small fish. I was a little worried about sharks, so I got the idea that I should shove the fish down the neck of my wetsuit (after I killed it of course). As I was doing it, I was thinking, "how come I never thought of this before?" "I wonder if it is the depth and if this is a really stupid idea?" I was real careful not to ram a dorsal spine into my throat at depth. Generally, I try not to come up with too many "new ideas" when diving that depth.

My buddy typically does another deeper wreck solo (max depth around 225-230) and he also uses air. My personal comfort level is right about 200 on air, but I've gone a little deeper a few dozen times.

I have tears coming down my face! "After I killed it of course." Well, of course, every PADI trained diver knows that! Sheesh!

 

[boomx5]

This link has got a funny video of a dry deep air dive.

Deep Air Dry Dive

 

[Kevrumbo]

Well, I've just tried 21/25 mix for an END of 30m at max depth 50m --Scootering around, there is no noticeable impairment; but as soon as I let off the trigger and started finning around against the current, I began to feel a slight buzz. Water temp here in Puerto Galera Philippines is 27deg C at depth with 15m viz & fair clarity.

Going to the old US Navy Base at Subic Bay this weekend and try some build up dives on 20/20 mix on the Sakura Maru at 54m (END 39m); and then next week will be Truk Lagoon.