PADI TecRec

[Big Blue Planet]

Mike,

CO2 is an issue. It is an issue on all dives regardless of gas mixture. I have seen trimix divers get god smacked at ENDs of 40 because of CO2 build up due to strong current. CO2 is the evil gas. At least we got you to admit that narcosis is not a huge a problem as it was once portrayed to be.

The course text does address the need for good breathing techniques. I did lobby for more detailed training on proper breathing mechanics. I call this breathing parameter. I spend a great deal of time on developing proper and optimized breathing in all my clients, even at the openwater level. I have been trying to get you to come to a freediving practice session for some time. I use the proper ventilations that freedivers use for maximum breathing efficency. I am not going to go over the techniques here. It would make the post too long. LOL But, 70% of the gas exchange in the lungs occur in the lower thrid of the lungs. The only way to insure optimized gas exchange is to use diaphramatically initiated breathing techniques> basically the visualiztion is imagine filling your lungs from the bottom and emptying them from the top.

This not so much about CO2 as it is about gas supply duration as well. The two go together. I do discuss CO2 in my programs because I am aware of the problems it poses to those who do not keep it in check. But, air is hardly an unbreathable mixture at depth. Helium based mixtures do provide less resistence, but the difference is minor. It is more about disciplines breathing parameter. Also, well maintained regs and ones that deliver gas well, but more important provide minimal exhalation resistence, an often highly overlooked feature in regs.

So, we agree CO2 BAD. Deep air to 165, not enough of an issue if CO2 is managed. I am more concerned with a trimix diver at 300 with a crappy breathing parameter than I am an air diver at 165 with a good one. So, we probably disagree on that note. Just not that big a deal if trained properly. If the diver let's it get away from them, any diver on any mix, it can be as bad as running out of gas or worse. So, I do not see CO2 a s an arguement against air to 165. I see it as an arguement against crappy breathing technique any where.

G2

 

[Mako Mark]

increased C02 retention and accumulation that is caused in part by the density of the gas at depth.

Im vague on the latest info on this issue, and you repeatedly bring it up, so help me out, where can I read more about this. Even Pyles deep stop article only touches on the subject? Who IS presently doing research on this issue, and does everyone else agree with you on how big a deal this is.


Roakie,

The quote didnt exclude every other training agency in the world either, and unless you are a PADI Course Director, I think you are speculating about their relationship with PADI.

The reason that Course Director has nothing to do with it is that Course Directors can not teach tec diving unless they also have the additional tec skills, knowlege and credentials. Teaching instructors is a specialty area, as is tec diving, but they are apples and oranges really and therefore mutually exclusive.

The fact that gary is or is not a PADI Course Director is irrelevant to his discussion about the Tec Deep course and its development IMO.

 

[Big Blue Planet]

On Your Knees Boy,

You have to understand that in the Tec Deep course we are allowed to do pool level work in the ocean. So, put that context to when I say on their knees. Believe me I do not take students into the openwater for functional dives and accept contact with the environment knees or otherwise. Things happen, but that leads to retraining. I have spent upwards of seventeen hours with some students in pool and limited open water getting them to a point where they could function on a working dive. They came in supposedily with existing technical quals.

The Tec Deep course has zero problem with me requiring the students to be in working position for the entire dive. But, the decision is that of the instructor. The goals of the course are to have people be functional and effective. I would hope that at this level that would mean conducting working dives with minimal environmental contact. The Tec Deep course is often the first time people are in double with PADI. So, there is going to be time spent on knees in the pool/limited openwater to help deal with issues and introduce techniques like valve shut down drills. In the openwater, this is common to do for the first attempt son that complex skill, but this is moved to mid blue water once none skill development dives are begun. It is an evolution from simple to complex. Once I have students involved on working dives and for all but the earliest skill dives, they are off the bottom. I am not so concerned with what happens during a course as long as the instructor has the students not contacting the bottom for last half of the dives. But, to say it is unacceptable for the entire duration of the course, we will have to disagree. I will say it is unacceptable for the final dives of the course. If you want a number of dives, I would say the simulated and actual decompression dives. Otherwise, just not a big deal. The students understand where they are going. If they have issue I step back and work with them, I do not send them away.

G2

 

[Big Blue Planet]

IBC,

No one seriously considers Isobaric Counterdiffusion to be an issue. We went around and around on even including it. It is in there because it is present in the community. No one views it as a real potential for any end users. The odds of it ever being an issue are so remote that it is probably not worth discussing, but it is out there. Beside the average trimix diver will be reach depth or saturation levels where it would even be possible. Even then the risk is still very tiny and theoretical. It could come into play as more use habitats for long decos from very deep dives, but that is easy to compensate for. So, no there is no one that views it as an issue. See , we agree again. Remarkable.

I did not comment directly on Drew's comments because for one I am not him. He is a very good friend and I do not remember the context of the editoral and was not in on the discussion. I have no first hand knowledge of what was happening at the time. He is a very reasonable man and very progressive in his thinking. He comes from cave diving before you or I were even relaizing there was such a thing. I tend not to dwell on the past and things change. Does it even matter with where we are now. Things change and so do thoughts on things. That is all I can say really. Do not have enough info to say anything else.

We do disagree on our core philosophy. GUE believes there is only one way to do a lot of what they do. I do not. I do not believe in comprimises on core issues of survival, but there is a lot of room for many techniques and environments of the world. Plus, the reality is sometimes if you want a program to exist you have to be open to other ideas. GUE is smale enough to dictate things. Imagine trying to build concensus in the world of PADI. I was involved with development because I want a course I would be willing to teach. Am I 100% happy with it, no. But, I know many GUE Instructors that are not 100% happy with their courses either. I do not teach the Tec Deep course as writen, but I do fulfill the standards stated there. It has added good things to my offering and I do not agree with all of it, but those are minor. It did come to a point where either we have a program that is as good as it can be or do not do one. I prefer to to get most of it done well and have very minor issues left rather than not have a good program exist. It is much more difficult when this comes down to partical matters like getting all the players to agree. For what could happened, I feel verys trongly that it is a great beginning. It will evolve as we learn more, but every system does. The program is solid. Bias hat on now.

I can tell you there was a great deal on internal resistance to even having the programs in the first place. It is not viewed in the same light as the rest of what they do. It is clearly stated in the philosophy of the course that tech diving is not for everyone. I think they go out of their way to talk people out of even thinking about tech diving unless they really feel they have a need to.

And yes, Course Directors are independent of PADI and I do have my own opinions. I am clear where I disagree and if I do disagree I pick up the phone and talk to people about it. I may not always get the results I wish to have, but I am hear. I happen to be friends with many at the office and I do contract with them from time to time, but believe me ask anyone that knows me there, I am never short on voicing things when i have a problem with something. They do listen and they are not some ivory tower that dictate things to the world of diving. My two cents, if it is even worth that. LOL

Cheers Mike,

It is fun. Enough for now.

Grant

 

[Mako Mark]

Ok so i did some searching lastnight about CO2 retention in materials I have in my library, here is what I found.

TDI barely touches the subject (less than 2 paragraphs) in trimix, adv nitrox, and stage deco, but has a little bit more in extended range manual. only 2 questions in the knowlege reviews.

IANTD, similarly disapointing (but I dont have all the manuals), BUT there is an excellent article in the IANTD technical diving encyclopaedia by Jolie Bookspan, who also coauthored an article with Rev Lanphier which appears in Immersed and is reprinted in the booklet by Lee Somers (NAUI, IANTD, MIT).

DSAT refers to the topic very obliquely but repeatedly without direct reference to CO2, rather as Exertion, dead air space and breathing resistance instead.

What I learned from searching through the books in my junk room was:

The scientists seem to believe CO2 has a dramatic effect on the central nervous system and the brains capability to function normally. This is usually manifested by unconciousness with little warning.

concensus seems divided if CO2 is highly narcotic in itself, or whether it is an exciter for other inert gas narcosis

There seems to be some disagreement on exactly what defines a CO2 retainer and this creates an argument about aclimatization to higher levels of CO2 tolerance in commercial military, apnea divers, divers with very low air consumption, and their propensity to have problems associated with co2

It seems very clear that the narcotic/anasthetic effect of Nitrous oxide is very different to Nitrogen Narcosis and deserves little further investigation except for dentistry and partygoers.

It seems very clear that adding Helium to the mix drastically reduces the physical density of the breathing gas, therefore laminar flow, bronchial turbulence and pulmonary breathing resistance, therefore enhances CO2 elimination. All seem to agree this is a good thing.

There is possibly a feedback effect, Nitrogen Narcosis decreases CO2 elimination by slowing the breathing response, which increases the levels of CO2 and CO2 enhances the effects of narcosis. Unconsiousness is the inevitable outcome.

There seems to be some distraction that CO2 retention and shallow water blackout are connected when the oposite is true, hipercapnea (CO2 retention) is the oposite of hypocapnia/hypoxia (shallow water blackout).
All seem to agree on deep water blackout.

Above 30 meters depth there seems to be little cause for concern.

What is a grave cause for concern is while investigating the effects of CO2 on divers, the United States spent taxpayers money making navy divers ride bicycles underwater???

Now the PADI underwater basketweaving specialty has been mentioned on this thread, but underwater bicycle riding is a new one on me and I think it needs further investigation.

What have I learned? CO2 is not only important during O2 tox discussions, but also during DCS and Narcosis discussions.

Many seem to think Helium if logistically possible should be introduced betweent eh 30-40 meter mark, however logistics, certification and the mythology of the more exotic helium gas often prevent this, and as we all know many have dived a lot deeper than this without having a problem with CO2.

 

[Father]

I'm coming in on this discussion a little late and I don't have time at the moment to see if this question was already asked and answered but...

Does each TecRec certification have a depth limit attached to it in the same way OW, AOW, and Deep Diver?

One site I checked out has each respective 4th training dive at 130' (TecRec40), 145' (TecRec45), and 165' (TecRec50).
I wasn't sure if this implies that each certification level "allows" (or imposes) an additional depth limit.

 

[DevonDiver]

Yes, those are the depth parameters (limits) of the TecRec courses.

40 - 45 - 50 - 65 - 100 (meters)

Each course introduces greater complexity and new 'tools' for the technical diver. I'd summarize these progressive bounds as...

Tec40 - Basic gateway into technical diving, but also great for recreational deep diving. 10 mins non-accererated deco using >50% O2 for conservatism as an ascent gas only.

Tec45 - Full decompression using >100% O2. Single deco gas only. Keeps it simple, mitigating the risk of Oxygen Toxicity from deco gas switching mistakes.

Tec50 - Extended range, deep air, using 2+ deco gasses >100%.

Tec65 - Normoxic trimix (>18% O2). Allowing Extended range dives with appropriate END.

Tec Trimix - Full trimix to 100m depth.

I've also seen standardized distinctives - Tec45 Trimix and Tec50 Trimix.

 

[Father]

Thanks Andy.
Do you know why PADI didn't match TDI on the depth ranges that their courses allow?

 

[DevonDiver]

I'm not sure why PADI limited their extended range / deep air to 50m (1.26ppO2). It extends back to the old DSAT Tech Deep course, which was subsequently split into the Tec40/45/50 program. I suspect it was deemed a prudent limit for narcosis, rather than just opting to limit at 1.4ppO2.Depth aside, I do like the structure of the the Tec40/45/50 program, especially how it progressively introduces risk elements at each stage. In contrast, many AN/DP/ER programs are weak at the front-end (AN), too heavy in the middle (DP) and then have nothing much new to add at the rear (ER). In general, however, comparison between different agency tech programs needs more than just a simplistic view of permissible depths.