Race to the Depth, Slow descend vs Fast descend

[Bennno]

I guess you are not understanding what I'm trying to point out.

I understand what you're saying. What you're doing is not unusual, I've seen it many times before. You want it now and you don't want to wait. There are people that go from OWD to cave and/or ccr instructor in a couple of years. I think most agencies let people progress too fast in general.

I'm not that optimistic about time and money in this planet as you are.

You're on 'tec dive' vacation in the Caribbean and you have taken at least some courses, so apparently you're not poor.

 

[Remy B.]

Who are those INTS and DMs you speak of?

In Accidents and incidents you can find them, there was an accident in Mexico, not so long ago, well known Instructor and Divemaster die, on what I see a very stupid way, they were asking for it, 1000's of dives on them yet they attempted do go for a deep booze on singles, and on fast descends.

Here in Curacao, as well in other parts of the world they do these deep dives, then I will ask again, who is safer the one that did the training and follow the know limits and have redundant equipment or the ones with 1000 of dives that don't, I might be wrong but to me it appears that training go over experience, I see it in day to day work as well.

 

[Remy B.]

You want it now and you don't want to wait. There are people that go from OWD to cave and/or ccr instructor in a couple of years. I think most agencies let people progress too fast in general.

I agree with you, but it is what it is, I guess they ( agencies and instructors alike ) have to put a meal on the table as well, but I don't think it has been 100% arbitrarily, to put the minimum amount of dives for this, or that or it, at the end they ( agencies ) rely on the good judgement of the instructors.

No body shall be allowed to be Instructor with less than 500 Dives on it and a lot of certifications, but it just happen that it doesn't take that much, which I think is wrong but I'm no body to say so, it is just my perspective.

My Tec certifications were not giving easy, I had to do more than 15 Immersions with the INST and DM before we were allowed to proceed to the Exam, and not counting the ones I did with the other students going over the drills.

When I was looking for Tec instructions I was between IANTD and TDI, but I decided with TDI as I already had my TDI nitrox that I done in Bonaire and the Agency have good learning materials, I knock on the door of TDI, the very first thing my Instructor told me was, doing the course doesn't guaranty you that you will have a Card at the end, I don't give them out easy, until you don't do the drills and procedures correctly we don't go to the next level, but first you need to dive with me and see how you do, after I did he told me, you are "OK" but need more practice

With that said, it was by his judgement that I had made it and approve my Tec courses, I realized that OW and AOW aind sh... compared with Tec instructions, procedures and preparedness.


You're on 'tec dive' vacation in the Caribbean and you have taken at least some courses, so apparently you're not poor.

You are assuming, which is wrong, I'm not staying in a Hotel if that is what you think, I'm not in a Tec dive Vacations, I'm on vacations visiting my family, just happen that I took the opportunity to do these Tec dives with buddies, If I had to pay for Instructors to be my Buddies then those dives were never to happen, because I could not afford them, without coming short with money somewhere else, I only had to pay for my O2, so it came out just right for me.

The Tec courses and the few Tec equipment cost me a lot and it is just to get along, I still not have a Tec DC, I had to sacrifice other things to pursue Tec diving, not poor but not with extra money either.

I wanted to take Trimix this coming year but money vise It seems a illusion at the moment.

 

[Pullnglide]

I'm assuming your dive count is wrong, it will influence how some of your questions are answered. Normoxic with TDI has a prereq of 100 dives. IMO getting into trimix with 100 dives is wrong!! I would be a lot better off financially if I wasn't a diver

 

[DevonDiver]

Andy, while I agree with a big chunk of what you wrote, I'd be curious to see how many of them were also deep breathing versus shallow breathing. I've seen a number of people that were breathing very rapidly ("heavy breathing") but also breathing very shallow get spaced out on deep dives.

Yes, we do agree... and I expect our experiences of witnessing the narcotic effects of hypercapnia are probably similar.

In my mind, breathing versus hypercapnia is a 'chicken or egg first' question.

Inefficient breathing causes hypercapnia. But hypercapnia also causes shallow, rapid breathing. They certainly spiral, once initiated... and elevation of partial pressure on rapid descent will dramatically exaggerate the severity of that issue.

My most recent incidence with (what I firmly believe to be..) hypercapnia narcosis occurred only last October:

My technical diving student, a physically fit, large-framed, athletic male, had to complete a sidemount entry onto a static, light shot-line in some reasonable surface current conditions. We conducted a 3-tank decompression dive using air and 50%.

There was some pace needed to rapidly don primary and deco sidemount tanks, followed by a short fight against moderate current to get to the line. The student was slightly out-of-breath as we gave the "OK" to descend.

At the descent/bubble check, the student then opted to 'tread water' rather than attain proper neutral buoyancy. This didn't facilitate him getting relaxed and lowering his respiration.

Following the bubble/descent check we began our descent to 45m/150ft, at a descent rate around 18m/60ft per min, giving "ok" signals every 10m/30ft of the descent.

Immediately on reaching bottom depth, my student firmly thumbed the dive. Without hesitation we ascended and I noted that my student seemed significanly agitated and stressed.

When we reached 21m/70ft, I initiated a gas switch to 50%. Whilst we hadn't incurred deco, my reasoning was that this would eliminate any issue of gas contamination and/or help resolve CO2 issues. It worked. The student became calm and the stress/anxiety faded. The remaining ascent was uneventful.

Back on the boat, my student explained that as we approached bottom depth he was overcome by 'inexplicable' anxiety and felt he was "just about to panic". This was a new sensation for him, as he was a confident, fit and experienced deep recreational diver, with no past history of narcosis presentation.

I surmised that his experience was probably hypercapnia-related; triggered by the pace and exertion of our water entry and then amplified by his failure to complete bubble/descent checks in relaxed neutral buoyancy.

His learning points were:

1. To improve equipment and procedural familiarity so that entry and donning tanks required less exertion.

2. To get neutral on the bubble/descent check so that this phase allowed him to relax and lower his respiration.

3. To extend the descent check if he needed to calm his breathing...and to also use this time to evaluate his physiological and psychological readiness before committing to descent to bottom depth.

4. To consider a brief period of breathing deco gas on the shallow descent check to assist flushing his lungs and resolving possible hypercapnia-related issues at the outset.

5. To understand the critical impact of CO2 retention and the narcotic potential of CO2 when deep diving and to take effective measures to moderate that effect.

6. His decision to immediately abort the dive was 100% correct.

7. The importance of a solid team, effective communication and disciplined protocols in preventing the issue escalating into a more serious incident... especially in regards to respecting and acting without hesitation upon the principle that 'any diver has the right to abort any dive at any time'.

 

[Remy B.]

I'm assuming your dive count is wrong, it will influence how some of your questions are answered. Normoxic with TDI has a prereq of 100 dives. IMO getting into trimix with 100 dives is wrong!! I would be a lot better off financially if I wasn't a diver

I have more than 100 dives, but I can only call real dives 98, by the time I leave Curacao I will have them, so now the Trimix is a lack of financial, I don't know what can I physically learn with Trimix that I didn't in my previous trainings, I know I will learn new Theory, that is what I'm after.

If you see the TDI curriculum on Extended Range that is what I went thru with my previos courses.

There are actually two courses that will bring me new perspectives, that are extended range and advance wreck diving there I will learn more, and will be phyfically be demanded more as well, but unfortunadily with who I want to take these courses are in different continents making it another illusion .

 

[Pullnglide]

Trimix is definitely an expensive endeavor. To go from Normoxic through Hypoxic, $3k plus with training, fills, lodging etc... is not out of the question. I ended up with about $2500 all said and done and I think that was getting off a bit light. I don't know you from Adam so take my words with a grain of salt and please don't take offense. It seems you are more training course oriented than anything else. I would think more than 25% of your dives are training dives taking you down to 70-75. Nothing wrong with wanting to gain knowledge but take the time to enjoy it and gain the experience you need. Your doing the right thing by taking courses before attempting those dives but experience and diving several times of the month in your trained environments will do you a lot of good! You seem to enjoy your diving now but I promise you that you'll enjoy it even more if you do that. I wish you the best of luck in your decisions!

 

[Remy B.]

I can relate a lot to what happen with your Student on a Dive to 55m about two weeks ago

"DevonDiver, post: 7863111, member: 82070"]Yes, we do agree... and I expect our experiences of witnessing the narcotic effects of hypercapnia are probably similar.

In my mind, breathing versus hypercapnia is a 'chicken or egg first' question.

Inefficient breathing causes hypercapnia. But hypercapnia also causes shallow, rapid breathing. They certainly spiral, once initiated... and elevation of partial pressure on rapid descent will dramatically exaggerate the severity of that issue.

My most recent incidence with (what I firmly believe to be..) hypercapnia narcosis occurred only last October:

My technical diving student, a physically fit, large-framed, athletic male, had to complete a sidemount entry onto a static, light shot-line in some reasonable surface current conditions. We conducted a 3-tank decompression dive using air and 50%.

I had almost the same configuration, except for a additional small 19cf@ 80%

There was some pace needed to rapidly don primary and deco sidemount tanks, followed by a short fight against moderate current to get to the line. The student was slightly out-of-breath as we gave the "OK" to descend.

I had to don my tanks as well quickly as we were been drop first on the spot as the Boat had other clients Rec divers that were diving somewhere else. ( we drift back to shore ), the water was kind of choppy so walking with all the gear on the boat deck was not easy as well.

There was some current so we had to start the descend quickly, I was already agitated from the don and boat dance with my gear on, but can't say out of breath but definitely not my normal rate.

At the descent/bubble check, the student then opted to 'tread water' rather than attain proper neutral buoyancy. This didn't facilitate him getting relaxed and lowering his respiration.

What is "Tread water" ? ./ We bubble check at 2m give the OK and release the breaks, there I started to breath heavily

Following the bubble/descent check we began our descent to 45m/150ft, at a descent rate around 18m/60ft per min, giving "ok" signals every 10m/30ft of the descent.

I didn't pay attention on descend rate but I believe it was more than 20m/min because we reached 56m quickly, anxiety was on me and around 25m the window started to close. ( Tunnel Vision ), , this was something new for me and I know ( or at least I thought so ) it had to do with my breathing rate, which I could not pace down effectively

Immediately on reaching bottom depth, my student firmly thumbed the dive. Without hesitation we ascended and I noted that my student seemed significanly agitated and stressed.

At target depth I had lost 50% of my peripheral view, ( a good tunnel ) I knew I was in trouble and it had to do with bad exchange in my lungs and CO2 retention, I thought, I'm to far to the surface now I need to try to solve the problem now before I press the abort bottom, I went to empty my lungs to see if I eliminate the CO2, and when I took a big breath again the window opened, I started to breath slower, and everything went calmly to normal.

When we reached 21m/70ft, I initiated a gas switch to 50%. Whilst we hadn't incurred deco, my reasoning was that this would eliminate any issue of gas contamination and/or help resolve CO2 issues. It worked. The student became calm and the stress/anxiety faded. The remaining ascent was uneventful.

Back on the boat, my student explained that as we approached bottom depth he was overcome by 'inexplicable' anxiety and felt he was "just about to panic". This was a new sensation for him, as he was a confident, fit and experienced deep recreational diver, with no past history of narcosis presentation.

This tunnel vision was something new to me as well, I was already anxious at the beginning of the dive and went worse as I descend

I surmised that his experience was probably hypercapnia-related; triggered by the pace and exertion of our water entry and then amplified by his failure to complete bubble/descent checks in relaxed neutral buoyancy.

His learning points were:

1. To improve equipment and procedural familiarity so that entry and donning tanks required less exertion.
Definitely my fold, I shall had starting to don my gear when we left the dock, because the dive spot was not far.

2. To get neutral on the bubble/descent check so that this phase allowed him to relax and lower his respiration.

3. To extend the descent check if he needed to calm his breathing...and to also use this time to evaluate his physiological and psychological readiness before committing to descent to bottom depth.
I will work in this for my next attempt to the same dive spot, but specially I will go very slow on my descend and will my Buddy know that.

My last dive to 52m from the shore I let my buddy ( another one ) know that fast descend don't suit me well, and that we were going down slowly, this dive went perfect.

4. To consider a brief period of breathing deco gas on the shallow descent check to assist flushing his lungs and resolving possible hypercapnia-related issues at the outset.

5. To understand the critical impact of CO2 retention and the narcotic potential of CO2 when deep diving and to take effective measures to moderate that effect.

I empty my lungs with a good and lung exhale, is there another thing I can consider ?

6. His decision to immediately abort the dive was 100% correct.

I probably failed in this, I was taught to try to solve the problem and if it didn't press then the abort bottom, after emptying my lungs I felt in control again, but maybe it was better to press the abort bottom first.

7. The importance of a solid team, effective communication and disciplined protocols in preventing the issue escalating into a more serious incident... especially in regards to respecting and acting without hesitation upon the principle that 'any diver has the right to abort any dive at any time'.

I fail in this one, I had anxiety event on all fast descends, but never had the Tunnel Vision, and when I reach target depth I go to my normal breathing on all those dives, and was wrongly expecting the same for this one.

If I had communicated this to my buddy maybe he had thought to approached differently.

At the end we missed the initial target of 50m due to the current.

 

[dumpsterDiver]

I have never had tunnel vision or had symptoms of that severity on any of my thousands of dives. Even when swimming like a fool, holding my breath to stalk a fish, fighting strong current at 180 feet, getting tangled in steel wire solo in a strong current and a whole range of "stupid human tricks" on air at depths well past recreational.

Of course I have been dizzy, lightheaded, out of breath, stupid, had auditory effects - things like that.

My advice is that if you were feeling that bad and out of it, you came close to passing out - and all from NOTHING - just self-induced stress from a free falling descent. If a slightly stressful descent, puts you in such a precarious state, how do you think you will handle a true emergency and the associated stress? It sounds to me like you need to back off chasing deep air etc. until you have a lot more dives and experience to rely upon.

You also need to realize that 55 meters in not that deep on air for some people, but for others it makes them very uncomfortable and when you add in any physical exertion or some other significant stress, it can be very dangerous.

You also need to understand that drifting along at 55 meters with zero exertion and zero problems, chances are you are narced but you may not be able to tell. i dive a little deeper than that commonly and one of my biggest indicators of narcosis is that: I FEEL NONE.

When i am swimming around down there for 5 minutes and all of a sudden, i notice no narcosis, that is when i realize my mental concentration has been slipping and I am truly narced. Generally the whole time i am swimming around at that depth, i have a constant dialog with myself that goes like: You are narced, you are stupid, you are weak at this depth, is this (whatever activity i am doing) smart? What is my time? what is my air? How much deco do i have? I can't imagine being at 55 meters and having tunnel vision.. I personally would have been pressing the up button on my inflator.

To me, it sounds like too much too soon.

 

[boulderjohn]

In Accidents and incidents you can find them, there was an accident in Mexico, not so long ago, well known Instructor and Divemaster die, on what I see a very stupid way, they were asking for it, 1000's of dives on them yet they attempted do go for a deep booze on singles, and on fast descends.

I believe I know the incident in question. In that case the answer to your question about whether their 1,000 (probably much, much more) previous dives helped them is that no, they not only did not help them, they hurt them. They are possibly the reason that one died and another will never walk again.

I wrote about it before in relation to this incident, and I called it the "best I've ever seen" syndrome. They had done all of their many dives in Cozumel and in similar locations, and those thousands of dives were the typical reef dives on which they accompanied their customers. In those thousands of reef dives, they had probably never seen anyone who appeared to be any more skilled than they were. They may have seen many highly skilled technical divers, but those highly skilled technical divers would not be looking much different on dives where those technical skills are not needed. It would be very easy to assume that they, being among the best that they have ever seen, are among the best in the world. They know people go to 300-400 feet, and since those people aren't any better than they are, why can't they go to 300-400 feet themselves?

In the aftermath of that discussion, I was shocked at the lack of knowledge about deep diving shown by some of the discussion participants. The victim who will never walk again wrote a lengthy confession (mea culpa) in which indicated they had never understood the extent of the danger narcosis and oxygen toxicity can pose when diving with air at those depths. A very well-known Cozumel dive operator had a private exchange with me over the incident, and that operator--also with thousands of dives--showed a shocking lack of knowledge of certain issues related to deep diving. For example, that operator could not understand how they could have run out of air when they went from 300-400 feet and back until I demonstrated the simple math showing how much an impact that kind of depth has on the rate of air consumption. These people did not realize that being the best they had ever seen would not cut it when diving beyond those familiar depths.