Mass confusion about computers????

[RayfromTX]

Ken
I see your point that if someone claims that an algorithm is safe because they have many safe dives with it then what should be acknowledged is that if the dives were not taken to the limit of the algorithm then it doesn't mean that the algorithm is safe if regularly taken to the limit. Of course nobody on this thread has specifically stated that DSAT is safe to dive to the limit because of their personal experience. It is valuable to make your point but to make your point based on what Craig said isn't the best way to make that point and....

Craig
You make a very valid point that what you have learned about the safety of DSAT is really only valid to you, your body and your style of how you use it.

It's all very interesting to someone with my level of experience and my goals for where I am headed with my own diving.

Tables, charts and algorithms are quite visual for me and I enjoy studying deco science. It must be quite daunting for those with minds that lean the other way. My dive buddy is never going to check my math on my gas plan. To think otherwise would simply lead me to a false sense of confirmation. A lot of diving seems to be recognizing your skills and limitations.

 

[Eric Sedletzky]

Man ... I had exactly the same experience with my UTD dive buddies. I used to dive with a Suunto Gecko - Zoop and my UTD buddies would do ratio deco with the same staggered ascent you described above. My RGBM driven Suunto computer would get furious while I attempted to follow their profiles. My UTD dive buddies would always have more bottom time and it made me think that if the entire purpose of spending money on a dive computer is to give me more bottom time then why is my Suunto failing to deliver that? Isnt that why we buy a computer in the first place? It makes no sense why you would have a 430.00 USD Suunto Zoop which is giving you less bottom time then some guy doing ratio deco on an 89.00 USD bottom timer and repeatedly getting away with it! I did not understand decompression algorithms back then nor did I understand ratio-deco so I asked on scubaboard. You can look at those ratio deco threads that I started a while back and you will notice that those replies were given at time when "ALL DIVE COMPUTERS WERE RIGHT." In other words, it doesn't matter whether the computer is running Buhlmann, VPM, RGBM, DSAT etc. as long as it is a computer it has got to be right!!!

As we revisit those threads in the light of what we are beginning to understand about decompression today, it turns out computer users that were running VPM and RGBM were basically on the wrong side of history. Buhlmann profiles with very low GF-los that intended to mimic deep stops were also on the wrong side of history but not as wrong as the VPM and RGBM. Since UTD was also attempting to follow these bubble models at the initial part of their ascent strategy, UTD was also in the same risk basket as these other computer users using RGBM and VPM.

Since UTD was a computerless crowd, they updated their e-learning, never had to reprint any books and the entire agency switched from deep stops to "relatively" shallower stops without any of their certified divers having to purchase a new computer. Technical divers who were on high end computers like Shearwaters etc were also able to incorporate shallower stops by increasing their GF-los while reducing their GF highs on their computers. The only crowd that remains stuck in the past is the recreational diver who was sold a dive computer. Since RGBM was the preferred algorithm in most recreational computers and three major manufacturers (Suunto, Mares and Cressi) used this as their default algorithm, chances are that in another five years time, if you will ever come across RGBM it will be in the hands of recreational divers diving in computers. Unlike UTD or other DIR divers, your average recreational diver does not have the training to plan a dive without a computer and modify his ascent to reflect whatever HE believes to be modern decompression thinking. Unlike the technical divers who own high end computers, his entry level computer does not give him the option to modify gradients factors to reflect modern decompression thinking. He will be the only one left at the mercy of the RGBM. The good news for him is that at recreational depths RGBM generates stops not different from dissolved gas models so he will not encounter "deep stops" for which RGBM and VPM take criticism for. In other words, he is not in any danger as per say. The bad news for him is that on repeated dives, RGBM will shorten dive times and become really really annoying. If the only advantage of a dive computer ever was to give you more bottom time, then RGBM will lose that advantage rather rapidly in repeated diving.

In the end you have to ask whether you prefer gadgets over education or education over gadgets? Ideally, I would like to have them both but since they both require investment, the order in which I would like to have them is education first, followed by gadgets. Unfortunately we are in an industry where educator (instructor) is not making any money and the sales person (retailer) is the one who makes money. This means that gadgets will be sold first and the education you will get is how to run the gadget.

It’s kind of amusing.
A few years after I got into diving I got a computer. It seemed that was the direction diving was headed so I decided to go for it. A few guys I knew and dived with laughed and snickered and called me a weenie because I sold out and got something to do all the thinking for me. People with computers were seen as mentally feeble, weak, sell outs, not as good, because they were lazy, stupid, or calculation challenged, and weren’t using the computer “between their ears”.

Now days people are considered a throw back and an ignoramus if you don’t use a computer. If you use a variant of a table, designing your own profile based on practical experience or common sense, adding stops, etc. you are called “dangerous” and “cowboy”.
....And it can’t just be any computer, it has to be the “right” computer, and everyone has their expert opinion on what that is and the algorithm it runs.

Wow! how times have changed.

 

[KenGordon]

Why is this such a big issue to you? He is not claiming to be testing the limits of DSAT.

Mass confusion about computers????

He (and you) are saying that DSAT is fine, and he is confirming that with the ‘evidence’ of his own experience. Since he is not diving to the limits then his diving while happening to have a DSAT computer on his wrist is says nothing about DSAT.

In the uk there are about 300 chamber treatments/year for bends. There will be more that didn’t go to a chamber. So we know, on average, people get bent now and again.

Encouraging people to buy the most aggressive computers available and claiming they are personally ok after years of use, as though the two are connected, adds to the normalisation of the view that diving to aggressive NDLs is ok.

SB is a terrible place for deco related advice.

 

[RayfromTX]

snip

SB is a terrible place for deco related advice.

Oh, I don't know Ken, without SB I wouldn't have heard your warning about making assumptions based on someone else's safety record with a particular algorithm. It is an evolving science and I've been exposed to it's evolution both past and present by reading the threads here. The members are pretty good at sorting out the inconsistencies and calling attention to the caveats as you have done.

There are still instructors teaching an emphasis on deep stops. In that instance you are likely to only hear one side of that issue. I have sat around after dives and listened to divers talking complete nonsense about diving and decompression protocols and I can assure you there are worse ways to get advice about deco than Scubaboard. That being said, I will use it only as a part of my learning experience, which includes my tec instructor and training literature but which will be checked against the latest deco science papers which I only know about because of this site.

I wouldn't dive according to something I heard on Scubaboard without followup study any more than I would dive according to what I heard around the table of beer after a dive with people I'd never met. It's the same thing except I can't see what beer they're drinking while posting.

 

[boulderjohn]

There are still instructors teaching an emphasis on deep stops. In that instance you are likely to only hear one side of that issue.

There are people at all levels who do not make any effort to update their knowledge of diving. That includes, regrettably, technical diving instructors.

• Not too many months ago, I heard a tech instructor talking about the importance of deep stops for dive planning. I mentioned the current thinking on this, and he was lost. He did not even know there was a controversy about it. He had learned about deep stops a decade ago, and he still thought they were the latest and greatest thing.
• Not long ago in a ScubaBoard thread, someone talked about the importance of extending decompression stops with the highest partial pressure of oxygen so that you could use the "oxygen window" and take advantage of the "oxygen vacancy" to speed up decompression. He had no idea that the study on which that theory was based had been discredited long, long ago. The idea was initially fostered by GUE, but they abandoned it years ago.

So if you are not reading a source like ScubaBoard, how are you picking up on changing thinking in diving theory?

 

[CAPTAIN SINBAD]

There are people at all levels who do not make any effort to update their knowledge of diving. That includes, regrettably, technical diving instructors.

• Not too many months ago, I heard a tech instructor talking about the importance of deep stops for dive planning. I mentioned the current thinking on this, and he was lost. He did not even know there was a controversy about it. He had learned about deep stops a decade ago, and he still thought they were the latest and greatest thing.
• Not long ago in a ScubaBoard thread, someone talked about the importance of extending decompression stops with the highest partial pressure of oxygen so that you could use the "oxygen window" and take advantage of the "oxygen vacancy" to speed up decompression. He had no idea that the study on which that theory was based had been discredited long, long ago. The idea was initially fostered by GUE, but they abandoned it years ago.

So if you are not reading a source like ScubaBoard, how are you picking up on changing thinking in diving theory?

This is an issue. Agencies that have e-learning can update their curriculum but those who sell text books have a hard time upgrading their courses. RAID and UTD have gone all electronic. Not many days ago there used to be a GUE link that had a very short explainer on the importance of oxygen window written by no other than George Irwin himself. I wonder why that link does not work anymore

 

[tursiops]

Mass confusion about computers????

He (and you) are saying that DSAT is fine, and he is confirming that with the ‘evidence’ of his own experience. Since he is not diving to the limits then his diving while happening to have a DSAT computer on his wrist is says nothing about DSAT.

In the uk there are about 300 chamber treatments/year for bends. There will be more that didn’t go to a chamber. So we know, on average, people get bent now and again.

Encouraging people to buy the most aggressive computers available and claiming they are personally ok after years of use, as though the two are connected, adds to the normalisation of the view that diving to aggressive NDLs is ok.

SB is a terrible place for deco related advice.

Thanks for actually trying to answer my question, but I'm not at all convinced by your answer. To be convinced, you'd have to show me a few pieces of evidence:
(1) there is a correlation between getting bent and the kind of computer you are using, and (2) it is DSAT-based computers that lead that correlation. Also, your use of agressive might better be replaced by least conservative. ALL the modern recreational computers are conservative, especially compared for example to the older Navy tables.

If you want some pure speculation, how about this: people getting the bends are those least likely to follow their computers, especially on bottom times, ascent rates, and surface intervals. I speculate those are Suunto users, because those computers are ubitquous, can be quite cheap, and have weird rules for their use.

 

[boulderjohn]

This is an issue. Agencies that have e-learning can update their curriculum but those who sell text books have a hard time upgrading their courses. RAID and UTD have gone all electronic. Not many days ago there used to be a GUE link that had a very short explainer on the importance of oxygen window written by no other than George Irwin himself. I wonder why that link does not work anymore

Having you course materials electronic does not help if people do not go back and re-read their course materials or if those course materials are not updated.

You do know, don't you, that at this point the only agency I know of that still plans decompression based on that debunked oxygen window theory is UTD? (That's the origin of the S-curve.)

 

[scubadada]

In fact, what I do has nothing to do with other people, just me

OK @KenGordon

We'll leave it at that. I have something thats works very well for me, hope others find the same.

Good diving, Craig

 

[DavidFL]

Mass confusion about computers????
SB is a terrible place for deco related advice.

In my own case, SB led me to watch a video of a presentation by Simon Miller given in South Africa that I wouldn't have likely found otherwise; other SB discussions led me to buy and read (more than three times now) Deco for Divers; that led me to follow and then dig for threads on SB and various rebreather forums about the NEDU study; my effort to try to separate the personalities from the postings in all those threads improved my own awareness of deco theory, led to buying a different PDC, continuing to compare the new computer to the old one on over 100 dives specifically looking at the "heat maps" generated by a model for tissue loading through the dive profiles.

I'm not sure SB was the place I got advice, exactly, but it sure was the place that brought me information and links and discussions to consider.