Redundancy Required for Decompression Diving?

[CuzzA]

For what it's worth, I'm currently reading the ART manual for IANTD and not only do they teach redundancy for deco, they teach redundancy for any dive deeper than 60 fsw.

 

[Octopusprime]

I agree there is no scuba police. However you can not take padi tec40 without redundant air. Tec courses teach you to be Self dependent your buddy's air is not in your reserve calculation.

Personally I take a bail out pony on any dive with a max depth at or below 100ft. Maybe shallower... Better to be safe. A true redundancy should not be in the planned air requirements. Last year I took my pony on every boat dive and never had it filled. Finally had it filled at end of year with 900 psi in it and I used it I multiple practice dives simulating deco and out of air drills.

Better safe than sorry.

 

[Bennno]

Have you never learned of better ways to do some things and incorporated them into your diving without formal training?

I have. There is a lot one can learn outside of formal training.

 

[Storker]

Have you never learned of better ways to do some things and incorporated them into your diving without formal training?

I was certified after formal training. I really learned to dive (at least I believe that I can dive now...) in a club environment. No formal training in that club environment, a lot of monkey see, monkey do, some gentle tutoring. A couple of years ago I switched from a normal octo setup to a LH/BO setup, with no formal training. A little mentoring, though.

 

[dumpsterDiver]

These aren't things prohibited or warned / recommended against by your training agency (virtually every agency).

In fact, all of them can be/are taught by representatives of that agency.

The issue here..... doing decompression without appropriate training / qualification / equipment / protocols.... differs because it's specifically prohibited by training agencies.

So which is worse?

To do decompression diving without training and using ALL the right equipment and procedures or...
doing deco diving with no redundancy and ALL the right training?

 

[Storker]

So which is worse?

To do decompression diving without training and using ALL the right equipment and procedures or...
doing deco diving with no redundancy and ALL the right training?

You don't seriously believe in that false dilemma, do you?

 

[KenGordon]

So which is worse?

To do decompression diving without training and using ALL the right equipment and procedures or...
doing deco diving with no redundancy and ALL the right training?

The second set know what the risks are. The first set do not.

Actually I don't think many people fall into your first set. But there are plenty who did some training, got the card and either never really had it sink in or forgot it. This is part of the problem with treating diving as an activity which can be learned in short courses. The bit after the course is extremely important.

Also, we are not really discussing people doing solo, deco dives on a single. Just the edge case where the reduntant gas is carried by a buddy. I think if you sat down and analysed the difference in risk, failure scenario by failure scenario that where the air is is not the major issue so long as buddy skills are ok. Of course buddy skills are often terrible, and indeed a large part of the ANDP I did was actually about the team. Concentrating on the kit rather than the soft aspects of 'technical' diving is to miss half the point. A redundant brain is as important as redundant regulators.

 

[Freewillow]

Again a reminder, we are NOT in the tek section here but advanced sport diving.

I am certified to do 42m deep dives and go up to a TTS ( time to surface ) deco dive. I am also certified to carry a deco stage with up to 100% oxygen.

During my training, all planning was done considering that you have lost your deco gaz.

The problem I have is that most of my dives are done in Asia, where luggage weight is a limiting factor. All my "serious diving" are done with my buddy wife that has the same qualification. Under 20m, we are NEVER appart more than 5 meters from one another. When we are under deco obligations, we are at "touching" distances.

WHEN IT IS WORTH GOING IN SMALL DECO? We calculate our "departure pressure" from the bottom as TTS x consumption of gaz per minute ( calculated generously) . To which we add a "safety" pressure equal to AT least the same value. Important to note that we do this ONLY in optimal conditions ( great visibility, calm water, other people around, great DM, O2 on boat, recompression chamber not too far away).

This means that my buddy is carying my redundancy. We REGULARLY practice OOA and other drills. My buddy is "attached" to me almost as a "deco stage" bottle.

Deco calculation is a "statistical" curve with a "statistically known" risk of ADD. The term DECO dive is a psychological barrier in a lot of brains. EVERY DIVE IS A DECO DIVE. It is not because you stayed away from the NDL that you will not have an ADD. It is not because you did not respect a small mandatory stop that you will develop an ADD.

Do I run a serious risk in a place where professionals are on the boat, where Oxygen is present and a decompression chamber is hours away? I do not think that the risk is behond reasonable.

 

[admikar]

I'm saying that, in my opinion:

1. Some aspects are out-of-step with modern, established, global practices due to a stagnancy in evolution and progression.

2. Tables and procedures often used don't reflect several decades of development in our understanding of decompression science, training needs and the advancement of effective protocols and procedures.

3. Liberal limitations on diver range can reflect a much more intimate, long-term, relationship between club coach and student; compared to short-course/shop type training.

4. Those liberal limitations shouldn't be sought by divers who haven't done the extensive, peer and instructor reviewed, training associated with long-term club activity.

5. CMAS, and other varied national affiliate clubs etc, DO provide what they deem appropriate training and protocols for limited decompression diving.

6. Regardless of inter-agency equivalency charts, it's an invalid assumption to presume that because a CMAS 2* diver can do deco, then a non-CMAS equivalent (AOW / Rescue) etc is trained or educated to do such diving.

7. The BSAC (/CMAS) training provision to achieve deco diving isn't modelled on a short, finite, course structure... it's a process of continued mentoring and incremental progression beyond base certification level training.

8. Nonetheless, CMAS, BSAC etc permitted deco diving in an era before the evolution of modern technical diving. Since that time, vast advances in equipment, methodology and best practices have influenced the global diving community. BSAC, CMAS etc have not evolved to effectively encompass that. They remain generally static and unchanged over multiple decades.

OK, I misunderstood your post. I agree with your point.
Only thing you got wrong is, CMAS 2* can not do deco dives. There is some deco theory and deco tables involved in training to level 2, but no training deco dives.
But, in lieu with your post, instructors get to know their students and start "after course" training with some of more capable ones.

 

[Storker]

in lieu with your post, instructors get to know their students and start "after course" training with some of more capable ones.

And this is one of the big strengths of club diving the BSAC and CMAS way: you don't pay your fee, do your class and get dismissed with a card. Formal training, mentoring and just diving together often are points along a continuous line. At least that's how it is when it works as intended.