*Mods - This RGBM/SUUNTO debate really deserves it's own thread*
When I am in scapa in October I expect I will be the only diver with a 'technical' computer. I expect people will be doing 30 minutes of stops on some of the dives with their suuntos.
That surprises me, based on my UK-located FB friends who tech dive, but I won't dispute it, because I'm not there.
With regard to the deep stops vs Pyle and RGBM it seems to me there is some slight of hand going on by Suunto. It does let you ignore them which I think might be a challenge for a true bubble model.
What you describe sounds like:
"....a traditional Buhlmann table would bring you as close to the surface as possible to get you as close to, but not exceeding, the M-value and keeps you there until you could either move up to the next decompression stop or to the surface without exceeding the M-value". Powell.M Deco for Divers
... but with (optional? ignorable?) Pyle stops added...
That wouldn't make it a Dual-phase model... a true 'bubble' model.
However, RGBM did stem from dual-phase. Wienke was integral to bubble model development (and an advocate of VPM until he wrote RGBM). RGBM is
supposed to provide very similar schedules to VPM. But from what you say, the Suunto does not reflect this in practice. That's confusing...
Does this mean that Suunto are dumbing down the model as it is displayed to the diver?
I can understand that for
emergency decompression, the recreational diver might be better served by having a simplistic deco schedule... ascend shallow and wait..... but I'd expect no enforced simplicity in a computer that used a dual-phase model specifically for technical divers doing calculated decompression.
I am interested in your point about how an algorithm selects a stop below the ceiling. Surely the ceiling is the shallowest depth allowed by the limiting compartment and so the stop just has to be below that? Obviously the particular m value to use depends on the interpolated gf for the depth or whatever m value generation scheme is in place. Other than that it is rounding to a convenient depth and not exceeding the ascent rates. Of course I could easily be missing something.
This is where, I think, many technical divers prefer the flexibility to influence their schedule. Of course, we're talking about Gradient Factors in relation to hard ceilings. The subtlety is whether an algorithm varies the M-value itself to adjust conservatism, or varies the conservatism below a constant m-value calculation.
On a technical dive, I like to know both factors... I like to know the m-value/ceiling... and I want to know my schedule to come up at a pre-designated point below that m-value. This gives me intelligent options to cope with varied contingencies.
For instance, on Petrel, I like the GF99 display (in addition to my desired GF setting that dictates the ascent). GF99 is my worst case scenario ascent.... when I might have to 'ride the ceiling' for some serious reason or other...
---------- Post added January 7th, 2016 at 09:56 AM ----------
... as something of a theoretical argument. Aren't all improvements and developments begun as an act of departing from the standard way of doing things?
Yes, they are. Technical diving is very pioneering. There's risk in that... trial and error. Errors have severe consequences.
Generally speaking, there are varied principles that apply in both technical and overhead (cave/wreck) diving. Those principles were developed over time...
and have stood the test of time. Developments and improvements tend to conform to those principles, even if technology changes. The principles are pretty broad really...
For a development to fly in the face of an accepted principle and be accepted by the community, it'd need considerable testing and debate.
Sidemount is the best current example of this. It doesn't break any of the principles, but it does break protocols. That's caused some division in the tech community. If you've not guessed.... there's always division on the tech community LOL. Small things matter.. Other examples are CCR training... and the development of decompression algorithms
(you can see that on this thread also...)
That said, providing the division is based on principles and safety, it's warranted. At no time is it based on "
do whatever you please, because who gives a crap? There's no authority...".
Something new gets tried. People argue about it hypothetically. Time proves who is correct in reality. Sometimes tech divers pay a steep price for that. Provided an individual understands the potential risks and consequences, they are free to make an informed decision on what sort of pioneering they want to do.
What doesn't make sense is pioneering in areas that are already known or predictable.
AI technology might prove useful to recreational divers. It's convenient. But recreational divers aren't dealing with multiple cylinders and multiple gasses. They won't die if they misread, or mis-program one of multiple cylinders into their AI computer. They don't have to switch between transmitters as they switch gasses.... adding complexity to a gas switch that'll kill them if they get distracted and mess up. They (probably) won't get bent if they forget to change a gas... and doing so screws up their computer inert gas tracking... or tox because they exceed their CNS/OTUs for the same reasons...
To a recreational diver, AI technology makes things simpler, easier and more convenient. Technical diving is different. The same technology just adds complexity... more steps... more chances for human error.... more chances for electronic failure.
I see this when training novice tech divers - even just with tech computers versus bottom timers. Sometimes task loaded students forget to change their computer gas selection when they do gas switches. Sounds silly, but isn't - given the task loading they face in the early stages of training. Then their computer becomes defunct because it's no longer accurately tracking the gasses they're breathing... potential for bent exists. If they were using slates and bottom timers they'd have nothing to change... no mistake to make... this gas, at this depth, for this time... move up, move onto the next line on the table. Simple... no room for that human error to screw things up.
Will AI and greater digital technology play a greater role in future tech diving... for sure. But, for now, I don't see the capability. AI would have to make technical diving easier, not more complex. To date, it doesn't achieve this benefit (IMHO). The principle of simplicity applies... and it's valid.
As for reliability... my movie playing SS-HDD glitches as often as my old DVD player... which glitched as often as my VHS player did before that.
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