Redundancy Required for Decompression Diving?

[Freewillow]

Its pretty easy to teach that lesson without taking the risk of heavily saturating oneself.

Here's how I approach it:

1. If using a GF driven computer (i.e. Shearwater etc), pre-plan a conservative NDL for the dive. Track that NDL and surface well within it. Set GF to something ludicrous (like 10/30) so that significant staged deco is reached very quickly. I use this method for running 'simulated staged deco' training dives with tech students, whilst also keeping dive parameters very conservative during the learning (and mistake making) phase of training.

2. Conduct a dive using an appropriate EANx mix, but leave the computer set for air. Plan the EANx NDL and dive within it. The computer tracks as per air, so you can enter lite deco safe in the knowledge you're well insulated from DCS risk. I use this to teach recreational divers how their computers will respond/display to emergency deco situations.

For recreational divers, my message is simple:

DCS risk is a grey area, not black and white. Modern decompression algorithms and no-stop limits keep divers reasonably safe from risk, even accounting for other predisposing factors.

As you approach no-stop limits, there is less insulation against those risks.. so one has to be much more mindful of contributory risk factors like ascent speeds, safety stops, proper hydration, exertion, thermal protection, body composition, cardio-vascular fitness and personal physiological issues.

Exceeding no-stop limits makes dives less forgiving. Smaller predisposing or dive management factors now have a more immediate and profound impact. The medical consequences of those factors occuring become more severe.

As those no-stop limits are further exceeded, the DCS risk changes from reasonable to unreasonable. From unlikely to likely. From non-damaging, to injurious, to potentially fatal.

Those risks cannot be eliminated, but they can be mitigated. Risk mitigation is possible through appropriate and specific training and equipment... all of which is readily available across the globe.

We are in agreement. As I said MANY times, you have a very positive contribution to a lot of posts in the forum. However, sometimes "general statements" are abusive for me. I totally agree with Patoux's quote:

"See, the problem with most of your statements, is that many of us read "train with me or you're gonna die" in it."

The idea to use computer with "crazy" GF is a good one. Having said this, very few non Tek divers have such a dive computor. So the idea to dive Nitrox on an Air computor is a great one - providing that you keep the REAL MOD in your head. This is by the way what I used to do with the well known old ALADIN pro that did not allow nitrox settings.

I don't recall seeing what you just quoted anywhere in this, or another, thread.

Who are you quoting exactly?!?

"Mortal sin" may not be the appropriate wording. Excuse my French . Devon Diver and KenGordon eluded to the "same thing". My experience is the same: Most of the PADI divers that I have seen consider diving beyond the NDL as a CLEAR NO- NO. The warnings that you have on some "recreational basic computors" also give you the impression that you are going to die or suffer if you enter into deco. The adverse result is that if a recreational diver enters into deco, he might freak out and then, really hurt himself. I have never seen this with experienced CMAS Divers.

I think that the old fashioned approach is actually the one taken by the big commercial agencies. By categorising deco diving as completely 'other' and having stuff like having to not dive for a period of time if a diver goes past NDL they have created a whole new category of pushing things. Having hard rules rather than having divers evaluate risk.

. I too have seen (and read about) so many people freaking out by going into deco. I think it is an important issue.

Depth: 95 ft, In Deco, 500 psi, No Buddy

The reason technical diving training exists is to mitigate those increased risks. It provides a significantly higher standard of dedicated training, along with a proven (accident analysis driven) equipment and techniques blueprint for preserving a high degree of safety and risk insulation. In short, it balances risk appropriately.

FYI, I do not consider myself a tek diver but I went throug IANTD Advanced Nitrox. I regularly dive with a 80% deco stage. So I understood the need for training. This is not the point.

You seem to imply that technical divers do minimise risks. I would love to see data on this - see later - . Yes I have seen diver suffer from ADD. The few people that I know that suffered from ADD to the point that they went to a recompression chamber ARE TEK Divers.

I am not so sure that the "average" tek diver makes safer deco than myself. They tend to use enriched gaz in order to shorten their deco time, while when I am using my deco with 80%, I switch on my enriched mix only on my main computor, but keep the deco time from my travel gas. So this gives me two deco runs: one safe and one emergency/bail out.

When it comes to data, I would be VERY interested to see mortality and ADD rates per dive for TEK/CMAS/PADI divers in order to see what is safer in the real world.

I would also love to see a comparison of ADD frequencies in 2 sets of people diving with the same GF: one group making long deco times with their travel gazes and another one making shorter deco times on enriched air.

I believe that without these data: any affirmation is "wishfull thinking".

 

[lermontov]

I am not so sure that the "average" tek diver makes safer deco than myself. They tend to use enriched gaz in order to shorten their deco time, while when I am using my deco with 80%, I switch on my enriched mix only on my main computor, but keep the deco time from my travel gas. So this gives me two deco runs: one safe and one emergency/bail out.
.

can you clarify that ? do you switch to 80% at deco stop but still stay on 21% time wise?

 

[Freewillow]

can you clarify that ? do you switch to 80% at deco stop but still stay on 21% time wise?

Yes, I keep one computor on the travel gaz: either 21% if I am diving on air, or 30% if I am using that 02 mix in Nitrox. Note That I am doing "small deco dives", deco obligation of a maximum of 10 minutes.

Let's take the following example. A dive of 24 minutes @ 30 meters ( Computor OSTC, deco settings Buhlman + GF 80/80. )

The profile on air gives me a deco stop of 9 minutes @ 4m.
The profile on air + deco 80% gives me a deco stop of 5 minutes @ 4m.


So one computor tells me that I can go out in 5 minutes in case of emergency. But I prefer to stay 9 minutes in order to minimise ADD risks.

Please note that the GF taken in this exemple are NOT my recommendation. Anyone has to choose his own computor settings in function of his factor risks, environment and type of diving.

 

[Colliam7]

See, the problem with most of your statements, is that many of us read "train with me or you're gonna die" in it.

Interesting reaction. From my individual perspective, I actually don't read that sentiment in any of Andy's posts (in this thread, or others). He has definite opinions, he articulates the basis for those, and that contributes to the discussion. His site is rich in information (and opinion, naturally) and gives evidence of extensive research. I don't always agree with everything, but I usually learn something. Frankly, his posts actually encourage me to want to 'do' a course with him, simply to observe his techniques.

 

[Diver-Drex]

What I don't see here (or in most of the other posts) is the gas planning that is required for any dive planned deco or not.

We did the gas planning, as I posted, based on square profile at our planned maximum depth. Turn pressure, ascent gas needs and rock bottom were calculated. I do this on every dive I make, deco or not.
I do agree that gas planning is not taught soon enough from what I have seen. I think that it is at least as important as NDL for OW divers to learn. At OW depths on an AL80 you are gas limited anyway. I suspect that as AI computers become more prevalent there is less of a chance of someone being taught how to do the calculations.

 

[Edward3c]

We did the gas planning, as I posted, based on square profile at our planned maximum depth. Turn pressure, ascent gas needs and rock bottom were calculated. I do this on every dive I make, deco or not.
I do agree that gas planning is not taught soon enough from what I have seen. I think that it is at least as important as NDL for OW divers to learn. At OW depths on an AL80 you are gas limited anyway. I suspect that as AI computers become more prevalent there is less of a chance of someone being taught how to do the calculations.

i require my students, at whatever level (especially instructors), to provide the gas calculations for the dive we're going to do. I do get some interesting responses, and head scratching.

 

[admikar]

I never heard @DevonDiver saying "train with me or die", but he does push a bit aggressively for training. I think he missed some points completely. No one in this thread said that divers should do deco dives with no training whatsoever , or any diving for that matter, some of only said that there can be alternate route to established "tech training agencies".
@Edward3c , I think gas planing is involved without saying, at least in my case.

 

[Rhone Man]

I never heard @DevonDiver saying "train with me or die", but he does push a bit aggressively for training. I think he missed some points completely. No one in this thread said that divers should do deco dives with no training whatsoever , or any diving for that matter, some of only said that there can be alternate route to established "tech training agencies".
@Edward3c , I think gas planing is involved without saying, at least in my case.

The dude is an ex-squaddie.

That's just how they roll.

 

[stuartv]

I never heard @DevonDiver saying "train with me or die"

Nobody said he SAID that. It's just that what he says does come across that way sometimes (to me, anyway).

No one in this thread said that divers should do deco dives with no training whatsoever

I didn't say that anyone SHOULD do that. But, I have said, and do think, that it's feasible to do it with no training. Where, by "training", I mean formal training with an instructor. I don't count learning it on your own, by reading the relevant texts, watching the available videos, etc., and practicing on your own, as "training".

My dad was a shipboard diver in the US Navy (i.e. not a Navy Diver). He brought his own scuba gear on his ship and when his chief found out, he became a shipboard diver by default. I asked him once what the deepest he ever dived was. He said he had some assignments when he was on the ship where he want to approximately 200'. I asked him if the Navy provided him any training on how to do that. Of course, this was in the 60s. He always dove double steel 72s anyway, but back then it was a single valve in the center of the manifold. And diving air, of course. He said no, they didn't give him any training. I asked how he learned to do it. He said, "I got the Navy Diving Manual and I read it." We are from north Florida, so before the Navy, his experience was diving the north FL black water rivers and caves. But, never anything very deep.

 

[DevonDiver]

I didn't say that anyone SHOULD do that. But, I have said, and do think, that it's feasible to do it with no training. Where, by "training", I mean formal training with an instructor. I don't count learning it on your own, by reading the relevant texts, watching the available videos, etc., and practicing on your own, as "training

Training is training.

Whether financially compensated or not, whether run to an agency syllabus or not. Training is training.

Training involves instruction in proper techniques, procedures, equipment selection and usage, assessment and feedback on performance.

Self-learning isn't training. YouTube videos and internet articles don't provide assessment and corrective measures. They may demonstrate a skill, but don't help a student properly achieve that skill for themselves.

In some cases, a diver might be equipped with sufficient baseline knowledge, ability and understanding of performance standards to learn from external media, but it's all to easy to get it wrong, miss critical elements, fail to identify dangerous errors or deficits... or to over-assess your own performance.

There doesn't need to be a card issued as 'proof of training', unless the diver requires one.

However, many qualified instructors will prefer to teach under the liability protection of a formal agency syllabus.

But there are instructors who routinely teach via personal mentoring and/or non-certification clinic formats (I am one who does this regularly).

And, of course, non-instructors who might mentor and assist fellow divers.

Therein lies the difference between an individual who effectively trains divers and one who merely delivers a training product...a pre-determined 'package' of skills and knowledge.

The ability to instruct a given activity is not determined by a plastic instructor card... but rather by true expertise in that activity, coupled with prudent risk management and an inherent ability to teach - to convey information and demonstrate skills accurately, to breakdown skills into sub-skills, to identify and remedy incorrect performance, to accurately assess strengths and weaknesses, to determine reasonable and achievable goals and guide the student in setting appropriate limits in tune with their performance and goals, to foster a suitable mindset and attitude in the student...and all the while ensure student safety.

That said, the difficulty faced by many divers is in ascertaining who is actually competent to safely and efficiently teach and who possesses true expertise in the field they will instruct.

An instructor qualification should illustrate such competency and expertise... but as most of us know, that's increasingly not true.