What limitations are you referring to as regards the computer? It’s possible there was an issue with the deco model used, or an underlying medical issue such as a PFO, but it’s hard to imagine the computer itself causing an issue.
Info Why are tables not taught in OW classes anymore?
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Eric Sedletzky
Contributor
There was a computer years ago that was malfunctioning and was bending divers. It was recalled. Can’t remember the name or model but it did happen.
The U.S. Navy tables are built upon a lot of chamber and real world diving tests. The computer algorithms are not. From what I have read, the computer software is not produced to any standard, and not tested in chamber tests. They are also proprietary, and therefore each one manufacturer's algorithm has a slightly different approach, which is why some allow more bottom time than others. I can find no scientific literature that shows tests being done by the manufacturer, although the manufacturers probably do these tests. They just don't publish them. So when you use a computer to what we used to call the "knife edge" of the NDLs, you really are trusting that testing has been done, and that the algorithms are correct. Here's another evaluation:
The issue is the actual testing and refinement of the algorithm used to determine the decompression limits. This is an interesting study, and anyone using a dive computer should read the entire document.Introduction
Whilst the US Navy has been very systematic about validating Navy dive computer algorithms, there has been little documented or published evidence of rigorous testing of the algorithms in commercial off-the-shelf dive computers. This paper reports the evaluation of four algorithms used in these − Bühlmann ZHL-16C; VPM-B; Suunto-RGBM; EMC-20H − by comparison with US Navy experimental dives with known decompression sickness outcomes...
...
Summary
Commercial off-the-shelf dive computer algorithms were evaluated by comparison with US Navy experimental dives with known decompression sickness outcomes and resultant statistical models. Four algorithms were evaluated: Bühlmann ZHL-16C, VPM-B, Suunto-RGBM and EMC-20C. This preliminary testing indicates that while none of the four passed all of these proposed tests with factory default settings, ZHL-16C and Suunto-RGBM could be made to pass by adjusting user-defined settings.
Validation of algorithms used in commercial off-the-shelf dive computer
Whilst the US Navy has been very systematic about validating Navy dive computer algorithms, there has been little documented or published evidence of rigorous testing of the algorithms in commercial off-the-shelf dive computers. This paper reports the ...www.ncbi.nlm.nih.gov
SeaRat
I found these recalls:
CPSC, UWATEC Announce Recall of Smart Dive Computers
www.cpsc.gov
TUSA Recalls Diving Computers Due to Drowning and Injury Hazards
Consumers should immediately stop using the recalled diving computers and contact TUSA to receive a free replacement diving computer.
www.cpsc.gov
Aqualung Recalls i330R SCUBA Diving Computers Due to Injury and Drowning Hazards
Consumers should immediately stop using the recalled Aqualung i330R SCUBA Diving Computers and contact Aqua Lung to arrange for a free repair. Consumers can download a software update through the DiverLog+ application or bring their recalled dive computer to their dealer or local dive center to...
www.cpsc.gov
SeaRat
The first line of the "Introduction" you quote mentions algorithms used and validated by the Navy. What are they? What kind of model are they based on? They had to have come up with the numbers in their tables from some place.
It’s cool.
Personally, I use computers. It allows me to run Monte Carlo simulations by projecting millions of scenarios overnight while I sleep.
Who knows, maybe if I didn’t miss this abacus class I would be able to run billions of scenarios?
I imagine old habits die hard but I don’t think there is always a reason to force them upon the next generation when there is no upside anymore (or limited upside). Sometimes it can make sense as it can have educational/pedagogical value, but sometimes the upside is just too small vs another teaching technique.
For example, I imagine one could argue that you can teach base 10 or multiplication visually with an abacus.
There had been a thread, more than a year back now, along with an informal poll, on what contributors thought were the most influential advances in scuba technology -- and most had predictably claimed that it had been the development of dive computers, to the tune of around sixty percent; and the view that I still held, was that it had been the SPG, which still garnered a reassuring thirty percent or so.
At the very least, few now recall diving without an SPG (I certainly don't); but older friends of mine still regale me with stories, along with "reserve air" and J-valves, while diving wrecks off New Jersey in near-zero visibility, and surfacing only when that breathing became labored.
Anyway, I had mentioned an account of diving at the far lower end of the technology spectrum, during an impromptu dive in Carmel, California. Conditions that day were absolutely phenomenal, in excess of 25 meters, and I usually carry a bare minimum of everything that I need, save for a tank, all kept behind the bench seat of my truck.
Upon returning to the site with a rental 80 cf, there were two guys, by the roadside, with about 16K of kit between them, from rebreathers to some of the fanciest of the Shearwater computers, including one that I had not yet seen at the time, with a heads-up display.
On the other hand, I only carried a single regulator that day, a decades old Cyklon 300, that I usually used on my pony bottles, along with the hope of rummaging-up an SPG somewhere in the truck, aside from a button gauge that was attached to the 300. I found one, in my bag, along with masks, extra hoses and NAUI tables, that I had had since college. I usually don't pack the pricey electronics unless directly headed for a dive, since I don't wish to cook anything, left in a hot cab; or, primarily, get anything lifted.
I hit the water, along with my analogue watch and dive gear while the rebreather crew were still performing their exhaustive pre-checks; spent more than an idyllic hour in the water, maxing out at about 18 meters, which dumped me out as an "H" on the "End of Dive Letter Group," if I recall; thought that a second dive would be damn well worth it, especially after seeing that I would likely have the place to myself -- since the rebreather divers had apparently fled without getting wet; and went to exchange tanks.
Nasty end of school day traffic on HWY-1; a desire for a mondo cup of coffee and a danish; and about ninety minutes had me back at Monastery Beach as a bouncy "E" in the "Repetitive Dive Timetable," where I spent another hour or so, maxing out at about 15 meters, and spent a good deal of time in the shallows.
I have since repeated that "lower tech' diving several times and it's a silent, absolute pleasure, without the ongoing distractions of staring at increasingly larger, multi-colored AMOLED computer faces -- all the while missing out on scenery and sea-life like nobody's business; or, else, just having to endure the constant shrill alarms of some diver's mismanaged pinging gear.
It also makes me somewhat nostalgic for that time when dive gear and even computers -- all but useless on their own -- were not more expensive than my college car . . .
At the very least, few now recall diving without an SPG (I certainly don't); but older friends of mine still regale me with stories, along with "reserve air" and J-valves, while diving wrecks off New Jersey in near-zero visibility, and surfacing only when that breathing became labored.
Anyway, I had mentioned an account of diving at the far lower end of the technology spectrum, during an impromptu dive in Carmel, California. Conditions that day were absolutely phenomenal, in excess of 25 meters, and I usually carry a bare minimum of everything that I need, save for a tank, all kept behind the bench seat of my truck.
Upon returning to the site with a rental 80 cf, there were two guys, by the roadside, with about 16K of kit between them, from rebreathers to some of the fanciest of the Shearwater computers, including one that I had not yet seen at the time, with a heads-up display.
On the other hand, I only carried a single regulator that day, a decades old Cyklon 300, that I usually used on my pony bottles, along with the hope of rummaging-up an SPG somewhere in the truck, aside from a button gauge that was attached to the 300. I found one, in my bag, along with masks, extra hoses and NAUI tables, that I had had since college. I usually don't pack the pricey electronics unless directly headed for a dive, since I don't wish to cook anything, left in a hot cab; or, primarily, get anything lifted.
I hit the water, along with my analogue watch and dive gear while the rebreather crew were still performing their exhaustive pre-checks; spent more than an idyllic hour in the water, maxing out at about 18 meters, which dumped me out as an "H" on the "End of Dive Letter Group," if I recall; thought that a second dive would be damn well worth it, especially after seeing that I would likely have the place to myself -- since the rebreather divers had apparently fled without getting wet; and went to exchange tanks.
Nasty end of school day traffic on HWY-1; a desire for a mondo cup of coffee and a danish; and about ninety minutes had me back at Monastery Beach as a bouncy "E" in the "Repetitive Dive Timetable," where I spent another hour or so, maxing out at about 15 meters, and spent a good deal of time in the shallows.
I have since repeated that "lower tech' diving several times and it's a silent, absolute pleasure, without the ongoing distractions of staring at increasingly larger, multi-colored AMOLED computer faces -- all the while missing out on scenery and sea-life like nobody's business; or, else, just having to endure the constant shrill alarms of some diver's mismanaged pinging gear.
It also makes me somewhat nostalgic for that time when dive gear and even computers -- all but useless on their own -- were not more expensive than my college car . . .
I don’t know. What it sounds like is that the U.S. Navy has developed its own dive computers, and uses those rather than commercial ones. I just did a search of Google, and found this:
SeaRat
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@rongoodman @John C. Ratliff
Are you talking about the Thalmann VVAL18 deco algorithm and the Cochran Navy computer?
Are you talking about the Thalmann VVAL18 deco algorithm and the Cochran Navy computer?
This is what I've found so far:
Apparently, Cochran Undersea Technology is no longer in existence. Mike Cochran passed away at age 77 (my age, incidentally) and the company ceased to exist thereafter. Here's an article from In Depth:
They Helped Foment a Dive Computing Revolution: RIP Cochran Undersea Technology (1986-2020)
Latin American distributor for Cochran Undersea Technology and certifiable dive geek Carlos Lander recounts the many firsts and innovations in dive computing created by microprocessor pioneer Mike J. Cochran (1941-2018). These included the first wireless air-integrated dive computer, automated...
gue.com
SeaRat
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