Are dive computers making bad divers?

[Rhone Man]

As for the bad planning - these people are on the do not dive with list.

That is a brilliant turn of phrase, my friend!

 

[HJeffreyM]

I would ask the OP the following question: You wrote your post with word processing software, not a pen or pencil. Did that make you a better or worse writer? Probably not. That's because either you had a teacher somewhere along the line who was able to teach you the basic rules of English grammar which you now apply no matter what writing instrument you use, or you didn't. Same for dive computers. Good dive instructors give their students a solid understanding of the basic science involved, along with a good dose of fear of what could happen if they mess with the laws of physics. Or they don't. As many others have said here, the computer is just a tool. It can't make you a better, or worse diver.

It's knowledge and practical experience that make you a good diver.

 

[boulderjohn]

Is there any published data to back this up?

I am not aware of DAN publishing these kinds of results, but whenever they are involved with a case of DCS, they try to gather as much information as possible. When my dive buddy got a fairly bad case of DCS a number of years ago, I provided them with the Ratio Deco profiles we had used on our dives that weekend. In cases involving computers, they try to get the computer data as well. These people will have at least a sense of what is happening.

It is hard to find reliable data otherwise. For example, when I was arguing some points on the use of Ratio Deco at altitude with my then technical diving agency, I was told that no one had ever been bent using ratio Deco at altitude. I responded that my buddy (mentioned above) had gotten bent using RD at altitude, and in fact our small dive group had 8 DCS cases over a few years alone. I was told those did not count, because in each case there was some other factor causing the DCS other than altitude or the Ratio Deco itself.

As an example, in two of the cases, the divers were together, and the made several miscalculations related to their dives and their application of ratio Deco to it. For example, they did not calculate their average maximum depth accurately, They ascended much too slowly to their first deep stop and the beginning of their profile, and they made mistakes in calculating the decompression profile after they began that ascent. They realized they made those errors after the dive because one of them was using a computer in gauge mode as a bottom timer, and it had the true profile of the dive. They could see how it differed from the one they thought they had done. It was argued that it was those errors, not ratio deco, that caused the problems. One could argue in response that making those calculations is an integral part of Ratio Deco, on the theory that "the computer between the ears" does not make the kinds of mistakes that a computer on the wrist will make. In this case, the computer between the ears made the errors, and that would make it a ratio deco error.

Another reason that the 8 did not count is the assumption that the divers in question had other physical problems, such as PFOs. The PFOs (or other ailments) were not officially diagnosed, they were just assumed to be there and be the true cause. Why was that assumption made? Because people do not get bent using ratio deco, so therefore there had to be another reason. A response to this would be that when other ascent profiles leading to DCS are analyzed, those kinds of medical issues are included.

By the way, I am taking a risk by writing this. I wrote about this several years ago, and I got an email threatening action against me for writing it. I was told that I would be reported to PADI for writing something disparaging against another agency, which is a violation of PADI member standards. I would therefore be subject to discipline if I were to mention those DCS cases again. (No, I'm not concerned.)

---------- Post added December 9th, 2015 at 10:56 AM ----------

I would ask the OP the following question: You wrote your post with word processing software, not a pen or pencil. Did that make you a better or worse writer? Probably not.

To carry that analogy a step further, I was an English teacher both before and after word processing. Word processing made it much, much easier to teach writing well. I know it is fashionable to think people cannot write as well now as they did in the past, but it is simply not true. All objective evidence is very much to the contrary.

 

[The Chairman]

Is there any published data to back this up?

I have no idea. He referred to data, so I'm guessing "yes".

 

[The Chairman]

I feel the only way to dive with a buddy is to keep watch on their systems (spg+computer) at all times

What a horrible way to dive. Learn to extrapolate. Ask your buddy what their pressure is after you use 500 psi. If they use less or are close, then they should remain so. If they use use more, than estimate when their turn should come and check just prior to that. This is basic OW level training. Of course, you should observe their breathing and adjust as necessary. You're here to dive and not babysit.

As for the PDC, if you remain relatively close... So will it.

 

[scubadada]

Ratio Deco is fantasy based at best. More divers, per capita, get bent on that, than any PDC or other table. Probably all of them combined.

I have no idea. He referred to data, so I'm guessing "yes".

This seems to be a pretty strong statement to make without any data to back it up. Hearsay hardly qualifies. If your source would be willing to share the background information, perhaps it would be different

 

[kelemvor]

I would ask the OP the following question: You wrote your post with word processing software, not a pen or pencil. Did that make you a better or worse writer? Probably not. That's because either you had a teacher somewhere along the line who was able to teach you the basic rules of English grammar which you now apply no matter what writing instrument you use, or you didn't. Same for dive computers. Good dive instructors give their students a solid understanding of the basic science involved, along with a good dose of fear of what could happen if they mess with the laws of physics. Or they don't. As many others have said here, the computer is just a tool. It can't make you a better, or worse diver.

Maybe that was a bad analogy, but probably not.

The fact is, using word processing software vs pen and paper can make you a better writer. Or, at least, it can make the things you write better. Since wordperfect in the 90's (at least), word processing software can correct spelling, grammar, sentence structure. It's even trivial for word processors to estimate the necessary grade level necessary for a reader to understand your paper. The simple word processor on scubaboard which I used to write this post even corrected several spelling errors for me. If you read my posts, it's pretty obvious that I'm no English major. Yet I never got less than an A on any English paper in college. Coincidence? I think not!

My point is, humans make mistakes often. Computers also make mistakes, but much less often. Also, a computer really only does what it was programmed to do. They're excellent at doing the same thing the same way repeatedly. Which, as I understand it, is what decompression calculations are all about.

 

[The Chairman]

I'm sure he would. I can't remember his name.

But please, show me one study concerning ratio deco. I mean a real study by real researchers. All I've ever seen on ratio deco are pothole telling us that it worlds or making excuses when it doesn't. Apocryphal accounts, but no science means it's based in fantasy to me. You might a different level of acceptance.

 

[The Chairman]

The fact is, using word processing software vs pen and paper can make you a better writer.

Much like digital cameras have improved the average photographer.

My point is, humans make mistakes often.

Every human gets narc'ed with depth. It's a given. That doesn't apply to a PDC. When they fail, it's usually in an epic manner. Nothing subtle about a PDC's failure. A human failure is far harder to detect... especially by the human involved.

 

[2airishuman]

...

So, here's the scoop. PADI created its RDP using research by its Diving Science and technology branch in the 1980s, long before the modern dive computer existed. The research team included Dr. Michael Powell, who is Dr. Deco on ScubaBoard, [.....]

Thank you for that writeup. I do want to make it clear that I appreciate the value, the accuracy, the difficulty, the improvement over the status quo, and the cost of the research that went into the tables, all of which your summary illustrates well.

Yes, they did exclude the depths requiring decompression. They figured that if you are going to do decompression, you are going to need further training, and you can get into that when you get that further training.

So is that what you mean by "dumbing down"?

It's not so much that they excluded deeper depths, it's that they excluded any deco information for dives within the listed depths but where the NDL was inadvertently exceeded.

I believe that it is a paternalistic, ineffective, and indeed counterproductive strategy to withhold information that has a valuable safety purpose (in this case, properly timing a deco stop when a mistake was made and the NDL was exceeded), because of the possibility that the information may be misused (in this case, by a diver deliberately exceeding the limits of their training).

Dive computers don't withhold this information, which is how we started down this rabbit hole.