Rise and Fall of the Bubble (Model) ?

[boulderjohn]

Why does it seem that at the same time recreational dive computers with adapted Buhlmann algorithms seem to be incorporating some of the bubble model concepts (from an uninformed layman’s perspective).

Thoes deep stop algorrithms were started about a decade ago, when the deep stop theory was in its prime.

I do have a question, however: when the NEDU design protocol was made available, did the people who are convinced that deep stops have some value contribute to the methodology used in the study before the study was done ? Or was the methodology only made public after the fact ?

The NEDU study was done when the deep stop theory was going strong, and it was was designed to test to see if it was as good as everyone was saying it was. As Simon said many times, at that time deep stops were all the rage, and just about everyone believed in them--including him.

 

[Roger Hobden]

Thoes deep stop algorrithms were started about a decade ago, when the deep stop theory was in its prime.

The NEDU study was done when the deep stop theory was going strong, and it was was designed to test to see if it was as good as everyone was saying it was. As Simon said many times, at that time deep stops were all the rage, and just about everyone believed in them--including him.

Thanks ! Very kind of you to let me know this crucial piece of information. Much appreciated !

 

[uncfnp]

Thoes deep stop algorrithms were started about a decade ago, when the deep stop theory was in its prime.

The NEDU study was done when the deep stop theory was going strong, and it was was designed to test to see if it was as good as everyone was saying it was. As Simon said many times, at that time deep stops were all the rage, and just about everyone believed in them--including him.

Is that the sum and total of it then? If deep stops are bad then the entire bubble model is obsolute? I admit that the theoretical models are far beyond my understanding but I thought there was more to it, ascents, repetitive dives and other nuisances that are incorporated into recreational algorithms that follow so called bubble models.

 

[Jack Hammer]

Oh yeah, and BTW DD and others expected the study to to show their deeper stop profile was more efficient than their shallower stop profile. It actually showed the opposite.

 

[boulderjohn]

Is that the sum and total of it then? If deep stops are bad then the entire bubble model is obsolute? I admit that the theoretical models are far beyond my understanding but I thought there was more to it, ascents, repetitive dives and other nuisances that are incorporated into recreational algorithms that follow so called bubble models.

We don't want to make the mistake of jumping to the either/or fallacy. We don't know enough to make any such judgment. It appears as if the early deep stop models were too deep for those first stops. That does not mean that a stop deeper than those in a pure dissolved gas model like Bühlmann is automatically wrong. More research needs to be done. I am personally using a 50/80 GF profile, which calls for deeper stops than does a pure dissolved gas model.

 

[dmaziuk]

Is that the sum and total of it then? If deep stops are bad then the entire bubble model is obsolute?

You'd have to call dissolved gas models thoroughly debunked and obsolete first then: recall that dissolved gas models originally aimed to prevent bubble formation. And then doppler ultrasound came along and showed that bubbles are always present -- epic fail.

 

[dmaziuk]

I don't think that Ross developed the software that calculates the bubble model, but that he just put a graphical user interface on top of Erik Baker's VPM-B code, that was V-Planner. In his many comments on this forum I got the deep impression that Ross' expertise is only on the Windows user interface programming, and iOS and Android app programming, but that he didn't understand neither the math behind the decompression models nor the physiology of decompression at all.

If he can take Fortran code and compile it into a windios gooey app, he's a way better programmer than about anyone I know.

 

[tridacna]

If he can take Fortran code and compile it into a windios gooey app, he's a way better programmer than about anyone I know.

print *, ‘I resemble that remark’

Dammit. I started programming with Fortran 77 on a Univac 1106.The thought of reverse engineering that code for Windoze is terrifying.

 

[StefinSB]

Doesn't help to have studied the maths of it if you completely lack any kind of understanding of the physiology that the math describes. Or completely refuse to accept said physiology.

Which Ross repeatedly demonstrated.

Well, you are opening a can of worms it seems unless you think that GF’s really describe human physiology. At the end of the day what “really” happens doesn’t matter to the vast majority of us as long as we have a model that provides us with a safe envelope to dive within.

 

[Storker]

Well, you are opening a can of worms it seems

I don't think so. Buhlmann ZHL-16 is a model. Abstracted, sure, but still based on real life physiology. And sure, GFs is an ad hoc hack to introduce additional conservancy into that model.

But my point is, if I were to choose who should implement that model into real world software, I'd really, really prefer a programmer who at least had an inkling of understanding of what the model is trying to represent rather than someone who doesn't understand crap about the real world system the model tries to represent.