Deep diving advice that goes against conventional thought?

[John C. Ratliff]

I know the history. My point was that learning RB as an entry point is no harder than OC if you take prior exposure to OC out of the equation. It's only harder in relation to OC.

Dale, I like your posts, but this one doesn't make sense to me. So let me reply to concepts.

First, you know the history, but I'll bet there are many readers of that post who do not. We have a responsibility to both explain things and educate those reading these posts.

Now, about the second concept you present. You state it's "...no harder than OC if you take prior exposure to OC out of the equation..." Actually, it is. First, there is more than one type of rebreather; there's closed-circuit rebreathers (CCR) and Semi-closed Circuit Rebreathers (SCR). Second, the rebreather equipment is more complex, and the dive student needs to learn about the loop, about the counterlung, the overpresure relief valve...there are 11 to 22 different components, dependent upon the unit. But someone being taught about rebreathers needs to know about all that are available, not just the one being used in the training. Then there is the maintenance, which is much more than simply rinsing out a regulator with fresh water. So your statement that it is easy to train on rebreathers may be somewhat true, but they are more complex machines than open circuit scuba. That you must admit; because they are more complex, you need more training on the units themselves.

You also ignore the physiology of diving, and using a rebreather with mixed gases. This is much more complex than training a diver to breath air, and the hazards of diving air. You need to know about partial pressures of oxygen, of signs and symptoms of problems with the mixture, etc. The physiology of diving rebreathers is much more complex. To keep from getting into problems, you need also to know how to program the dive computer to understand the mixture you are breathing (unless this also has been automated, but I don't think that's happened yet).

So I think this statement is somewhat misleading to people new to rebreathers. Take a look at the Wikipedia page on rebreathers, and compare it to the page on open circuit scuba.

SeaRat

 

[Storker]

Of course....And in the 50's and early 60's, anyone could buy a scuba tank and dive with NO Instruction. Lots of these guys even filled their own tanks. Maybe people were smarter back then..??

In the 50s and early 60s, people didn't see a problem with smoking, married women were supposed to stay at home and keep out of the workforce (or, as some Germans so delicately put it a few years earlier: "Kinder, kuche und kirche"), seatbelts were virtually nonexistent, ionizing radiation and nuclear fallout was good for you, teh ghey was dangerous and colored people surely knew their place in society.

Maybe people were smarter back then?

 

[DCBC]

Just wondering, for a true apples-to-apples comparison... if a certified Trimix diver, recreational or not, with some post-training experience (since presumably, those are the ones moving onto rebreathers due to the imminent Helium shortage as they anticipate further expenses) had a budget of exactly 4 hours to spend on additional training before they undertake their first-ever dive to 200 FSW, and they wanted to maximize their safety during said dive, what would be the better way to go: (a) take the rebreather class, and do the dive on a rebreather, on Trimix, while facing significant risks of rebreather diving with little practice, or (b) take an accelerated deep air diving course, and do the dive on air while facing significant risks of narcosis at twice the END they ever experienced, again with little opportunity to learn about their limits during their training...

When a CCR becomes 100% automated and improvements are made in design, there will be little difference in the operational complexity of CCR and open-circuit (SCUBA). My point is that divers are now required to possess less knowledge and in-water ability than at any other time in history. In today's competitive environment, the longer the training program, the less potential income. I do not underestimate some certification agency's desire to maximize profit. Diver safety and competence accounts for less than it once did.

 

[PfcAJ]

Both. I think you need to be familiar with OC prior to diving CCR, however being a seasoned veteran of OC does not make you a better rebreather diver. Are you aware of the laws of learning? Particularly the law of primacy? The law of recency can outweigh primacy, but kinesthetic memory is hard to override when making the switch to rebreather.
Furthermore if one learns CCR early on and is competent with air dilutent, the switch to deep with trimix is the same learning curve as a pure OC diver making the switch to OC trimix .





What is the differance between learning to carry deco bottles and learning to carry bail out gas? Answer...none.

Capital baloney. 1st class, prime time baloney.

When the CCR breaks, you're back to OC. All of a sudden, you need to be able to switch gases, move tanks around (don't drop anything), and do it all while maintaining your ascent rates, stop depths, and buddy awareness. "Carrying bailout" is not the same as using it. Any money can strap tanks to themselves and swim around. Being proficient in their use is quite a bit different.

 

[DaleC]

John, I don't think anyone will go out and buy a RB because of what I write

What I meant is that simple RB use is as simple as simple OC use. During the war, non divers were given a rudimentary education and an RB and off they went. They had no other system to compare it to so they just accepted it as something they could do. Yes, there were a lot of deaths, but many of those could be attributed to not understanding the real nature of oxygen toxicity. There were also a lot of DCS cases before that was understood as well. Fargue died deep because narcosis was not understood etc...

If we put both simple systems together we can see that some issues were present in one and absent in the other. The RB user needed to understand O2 toxicity but not decompression theory. The OC diver needed to contend with narcosis but not counterlungs. The RB user needed to monitor the state and quality of absorbent, the OC user the purity of air.

Of course today's RB units trying to solve operational issues are way more complex than war time units , but OC diving has also become complex. Learning to use a mixed gas RB is like learning to dive mixed gas OC. I won't debate the apples to apples of each, as I really don't do or need mixed gas diving, just as I wouldn't need an extended depth RB. What I am very interested in, in the future, is a rec limits affordable SCR that will allow me to do remote location dives without worrying about how many OC bottles I can haul along. Right now I own 6 tanks so, without a fill site nearby, that's the limit of my dives (unless I borrow tanks).

Right now I see two issues that are a barrier to widespread RB use: overall price and the reliability of the sensors. Skill and/or misuse will always be dependent on the individual.

If what is being said is that one should learn to dive OC first, I think I would agree, but not because of the complexity issue. I think OC gives a diver a wonderful chance to easily and (relatively) cheaply explore the range of diving that is available to see where their personal interests lie. RB requires a bigger initial investment in a system that may/may not suit ones long term goals.

 

[Nuribromanski]

Learning to use a mixed gas RB is like learning to dive mixed gas OC.

not really. it's more like learning to use something several times more complex and task-loading than OC ever is, while also going on a dive that could at any time turn into a mixed gas OC dive.

 

[DaleC]

Sigh...

If we assume one knows how to use an RB and one knows how to OC then using a mixed gas RB is like learning to dive mixed gas OC. Like, not the same, similar, as in covering the same concepts.

Anyways, this is just turning into some sort of semantic argument or axe grinding session I'm not aware of. Knock yourself out.

 

[tomfcrist]

Capital baloney. 1st class, prime time baloney.

When the CCR breaks, you're back to OC. All of a sudden, you need to be able to switch gases, move tanks around (don't drop anything), and do it all while maintaining your ascent rates, stop depths, and buddy awareness. "Carrying bailout" is not the same as using it. Any money can strap tanks to themselves and swim around. Being proficient in their use is quite a bit different.

Lets break this down for you then.....

No kidding when a CCR breaks you are back to OC....You must have an IQ of 160.

Stage management and gas switching is and/or should be a component of both an OC deep Class, and a CCR class at any level. There is no differance between learning to make gas switches or "how to use a Bailout bottle" between OC and CCR. The procedures are the same.

The real differance between Learning OC first and going straight to CCR (as it pertains to deep diving) is that an OC diver that transitions to CCR already knows how to conduct gas switches. The CCR diver that has no OC deep experience is going to have the same learning curve as it pertains to bailout plan and deco gas requirements as a new OC deep student.

Can you see it now? I sure hope so.

---------- Post added March 26th, 2014 at 08:05 AM ----------

not really. it's more like learning to use something several times more complex and task-loading than OC ever is, while also going on a dive that could at any time turn into a mixed gas OC dive.

Wrong. It can turn into a mixed gas OC ascent. Additionally, the complexity of the system has already been learned and drilled in the basic air dilutent CCR class, so I would venture to say its actually LESS complex and LESS task loading, considering the non depth dependent gas supply if nothing breaks, and enough bailout gas to make an ascent.

 

[PfcAJ]

Lets break this down for you then.....

No kidding when a CCR breaks you are back to OC....You must have an IQ of 160.

Stage management and gas switching is and/or should be a component of both an OC deep Class, and a CCR class at any level. There is no differance between learning to make gas switches or "how to use a Bailout bottle" between OC and CCR. The procedures are the same.

The real differance between Learning OC first and going straight to CCR (as it pertains to deep diving) is that an OC diver that transitions to CCR already knows how to conduct gas switches. The CCR diver that has no OC deep experience is going to have the same learning curve as it pertains to bailout plan and deco gas requirements as a new OC deep student.

Can you see it now? I sure hope so.

---------- Post added March 26th, 2014 at 08:05 AM ----------



Wrong. It can turn into a mixed gas OC ascent. Additionally, the complexity of the system has already been learned and drilled in the basic air dilutent CCR class, so I would venture to say its actually LESS complex and LESS task loading, considering the non depth dependent gas supply if nothing breaks, and enough bailout gas to make an ascent.

You must not understand the difference between doing it a few times in class and actually being proficient at it through repetition in real diving.

That doesn't take an IQ of 160 to figure out, but I'm sure you'll catch on.

 

[danvolker]

To me the bigger issue is the form of failure, and the recognizing of this failure....this requires a level of peripheral awareness far beyond what is required for tech level OC----failures in OC are far more pronounced and hard to miss....and much easier to deal with....less problem solving, less potential wrong solutions to deal with.

Also, the failures in OC are far less common --and easier for a dive buddy to intervene and assist in.

But....a tech level OC diver can be recognized as one either having great peripheral awareness skills and high stress problem solving skills...or not.....

I don't see a way to "cull" the field of poor peripheral awareness CCR divers that is as good as needing to develop the high level OC skills.....and one reason, is because the most insidious threat is the concentration on the "mission" and external stimuli going on during a serious tech dive--and you can't really simulate this in a pool.