"Riding your Computer Up" vs. "Lite Deco"

[lermontov]

What's "potentially" dangerous about exceeding an NDL when your sum knowledge and ability is derived from the Open Water course?

It's just plain dangerous.

"Risking your life" implies a modicum of danger, does it not?

Would you warn your kids that playing on train tracks could kill them? Or would you 'empower' them with transparency and teach them it's ok to play on train tracks if they "understood" that trains run on a timetable?

id tell them not to if they were children -thats a ridiculous analogy

 

[DevonDiver]

id tell them not to if they were children -thats a ridiculous analogy

It's not.

Adults differ from children (generally) because they can apply logic, better percieve risks and act safely based on common-sense and experience.

DCS risk is intangible. It's numbers on a screen which, by themselves, impart zero intuitive or instinctive risk warning. There's no preventative physiological signs and symptoms for DCS.

Education has to address that deficit. It has to impart a sense of risk and need for caution... where no human instinct or experience develops it.

When it comes to DCS... adults are as instinctively naive as children.

There's strong merit to an initially unambigious message.

Rationalization and intellectualization can come later... or opt to sign up for a considerably longer, more expensive and more comprehensive entry-level course.

 

[boulderjohn]

You know the answer as well as I. PADI faced the same issue with tables. It isn't like there weren't a choice of tables out there, they picked/adjusted one to suit their training needs. Standardized on it and continued onward from there.

Tell her to not to get overly concerned. In computer class, she gets to pick her own NDL.

I am really struggling with how to deal with this. The first quote above is just flat out wrong, and you really must know that because you have been told the truth many times, including in this thread. The second one is also wrong, as was explained in the last post I made.

PADI Tables: Before PADI created its tables in the early 1980s, recreational diving was done almost exclusively using the U.S. Navy tables. Bühlmann's research had not yet been published, and the first Bühlmann-based tables were years away. The U.S. Navy tables were quite unsatisfactory for recreational diving because they used the 120 minute compartment to guide surface intervals, which meant that divers had to spend a very long time out of the water between dives. The Navy's decision to do that was made without any real testing, and it did not matter to the Navy since their divers rarely did more than one dive in a day. PADI's primary goal in creating their tables was to find a way to make recreational dive schedules more doable.

To this end they did extensive original research using hundreds of divers doing thousands of dives. As scubadada wrote in post #413 quoting Mark Powell's fine book, "The M-values used for the RDP were adopted from the Doppler bubble testing and tested by Dr Merrill Spencer and tested by Dr Raymond E Rogers, Dr Michael R Powell, and the colleagues with Diving Science and Technology Corp, a corporate affiliate of PADI. The DSAT M-values were empirically verified with extensive hyperbaric chamber and in water diver testing and Doppler monitoring." Their research was published in peer reviewed journals. The work was both extensive and expensive. Dr. Michael Powell is Dr. Decompression on ScubaBoard, and if you do a search through that forum you will find many threads in which he talked about the work they did. The PADI tables were thus based primarily on original research. They did not ignore previous studies, but they did far more than just adjust an existing table. When they were done, they were fully invested in the results and made them the basis for their open water instruction.

In contrast, they have no investment in any of the algorithms currently in use by dive computers today. Yes, the DSAT algorithm used in many recreational dive computers is based on the original PADI research, but that research is now nearly 40 years old, and many of the other algorithms being used are based at least in part on newer research. PADI does not endorse any one computer algorithm, and it would be a mistake to do so since there is not anything close to universal agreement on which is best.

Choosing your own NDL: This statement is simply ludicrous, and it is hard to respond in any way that gives it dignity. When divers choose a computer, they choose a computer that has an algorithm, and sometimes more than one. Divers must make a choice about which algorithm they will use, and hopefully it will be an informed choice. Once they are using that computer, they must use the NDL that is part of that algorithm. They do NOT get to choose their own NDL.

 

[lowviz]

Tell her to not to get overly concerned. In computer class, she gets to pick her own NDL.

funny man...

Not really, it was an overstatement for effect.

She could start her computer dive class with either a conservative or an aggressive sport DC. The only real difference between them is the NDL. Thus, she gets to pick.

In my tables class, everybody followed precisely the same plan and instruction. That made it easier for both the instructor and the students. You never heard "Why are his tables doing that, while mine are doing this?"

My suggestion would be to have a PADI Training Standard option for both OW and AOW that would be implemented on any sport PDC platform.

In OW, your bells and whistles would warn you of upcoming deco and lock you out for the day if you entered deco. They would all behave exactly the same. In AOW, you get gentler warnings and are allowed a few minutes of deco with a required stop. Blow the stop and it locks you out for the day. They would all behave exactly the same. After class, set it back to what the manufacturer intended.

 

[dmaziuk]

So how is a newbie to pick the correct DC/algorithm?

Easy: start with a D and end with a SAT.
HTH, HAND

 

[dmaziuk]

My suggestion would be to have a PADI Training Standard option for both OW and AOW that would be implemented on any sport PDC platform.

In OW, your bells and whistles would warn you of upcoming deco and lock you out for the day if you entered deco. They would all behave exactly the same. In AOW, you get gentler warnings and are allowed a few minutes of deco with a required stop. Blow the stop and it locks you out for the day. They would all behave exactly the same.

A well calibrated perfectly spherical reference dive computer of uniform density. I See A Great Need.

 

[lowviz]

This thread has been personally valuable due to both the main discussion and the side discussions. One of the side discussions was particularly valuable. I now clearly see the differences between the OW/AOW agencies and BSAC. They both strive to produce safe and competent divers, but toward different ends. BSAC is more for ongoing local club diving with continuous improvement. Improvement that appears to be both club/peer encouraged and sponsored. Bit of a DIR flavor, no? On the other hand, the OW/AOW agencies are more towards vacation diving where the diver returns to his/her agency to gain further specialty skills only as the diver self-assesses and desires. This is my opinion from what I have read and experienced.

The initial premise of this thread was to explore an extended dive that was accomplished by either riding ones NDL computer up to the surface while constantly at the NDL (in order to maximize bottom time) or doing a direct ascent under deco conditions (with the same lengthened dive time) whose deco stops are imposed by an overly conservative algorithm. The comparison was valuable and the discussion was lively.

My post that set you off was due to the beginnings of an idea of mine that wasn’t fully formed at the time. It is now. This method of gaining enlightenment may be hard for you, so I’ll preface it with the underlying concept: Socratic Teaching

It is my current belief that the OW/AOW agencies did not rise to the challenge of dive computers. By not doing so they lost a fair measure of control over educating divers in their use.

So, you are an instructor. Consider starting class with three totally novice students, each bringing one of the three most different sport DC’s currently on the market. Do you teach each of them the thinking behind each of their DS’s (you, yourself said that there are differences) or do you try for a generic approach so you can teach them to dive first? A generic approach requires you to find and teach to the minimum common denominator among all the algorithms. Where is that on paper? Or is it not a generic approach, maybe there is some attempt to accommodate each student’s DC? “Why is that OK for him and not me???”

I don’t know the answers, I learned tables by chapter and verse. Same, same for everyone. We all progressed from that common ground to where we are now. Deco divers.

The ideal (my opinion) approach would be for the OW/AOW agencies to sit down together and hammer out a standard DC training algorithm. I don’t even much care how aggressive/conservative the training algorithm is, but it needs to be most clearly specified. One for OW, a similar one for AOW. Anyone who wants to sell a DC would need to offer these two training options in their DC. Now we have a datum, a stake in the ground, something to compare to.

The training algorithms could now include the OW/AOW agencies’ chosen penalties/benefits of riding up ones DC as opposed to a direct ascent when NDL is reached. By fixing the NDL to a collective standard, they could also decide upon an allowable amount of deco in excess of that NDL for an AOW student. At that point, there would be no need for nonsense like “mandatory safety stop”. Call it what it is. Deco.

Upon standardization, riding ones computer vs. ascending on NDL or managing (rather than fearing) a few minutes of planned deco could all be clearly taught as core skills to the recreational diver. Translation of these new skills to the student’s particular DC would be either on the student or as subsequent instruction.

There is a tenet in ongoing instruction, introduce the upcoming ideas but don’t belabor them. At present, the OW/AOW agencies vilify deco until tech...

A well calibrated perfectly spherical reference dive computer of uniform density. I See A Great Need.

Nice analogy. If you ever take Physics, you will be faced with a uniform, massless, weightless pulley.

It exists only to allow students understanding of the core concepts, uncluttered by irrelevant complications.

 

[scubadada]

Easy: start with a D and end with a SAT.
HTH, HAND

Grind your ax on your Cressi RGBM algorithm, though the edge may be dull

 

[scubadada]

A single training decompression algorithm will never happen, nor, should it. Training agencies could do a good job of educating new divers regarding the variation of decompression algorithms and the implications for their choice of computers. Much of this has to do with risk tolerance or aversion. I believe all of the commercially available algorithms are safe though I think I may be able to hurt myself with Buhlmann ZH-L16C with appropriately set GFs. I have been diving DSAT and ZHL for the last 80 or so dives to explore this topic further.

 

[boulderjohn]

The current PADI program uses a computer simulation that shows all the features of a computer as it goes through various kinds of dives. Students can play with all kinds of situations on the simulator and see how the generic computer works. They can then apply what they learned to the specific model they use.

All of the algorithms for recreational diving work plenty well enough. There is no need to pick one out.