DCS hit during final stop? Has it ever happened?

[MaxTorque]

looks out for a goat as ultimate un-bendable dive buddy...........


(don't take one with curly horns, they tend to get snagged on wrecks too easily.............. ;-)

 

[Wibble]

As you’ve noticed, all algorithms subtly disagree yet they all work.

A bit like a dive forum discussion.

Life’s like that.

 

[HKGuns]

In case you are interested, here is an article that may help you frame your reply.

Evolving Thought on Deep Decompression Stops

I've found this a very good presentation of this topic.

Even though he has this funny accent, Dr. Mitchell explains this topic very well with graphics and charts and stuff.

 

[MaxTorque]

Another "thought experiment"!

Given that the vast majority of divers now use some form of dive computer, and given most DC's both log the dive and are able to push that info up to a internet connected PC, don't we already have a way of carrying out the worlds biggest deco study, effectively, almost for free?

At each surfacing event, the computer would pop up some "rating" quesitions, allowing the user to fill in their subjective thoughts on the deco performance and symptoms of DCS, and all that gets fed back to some server somewhere where the mother of all analysis algorythms tries to make sense of it all?

From 3m pool dives, to 300m world records, all the data, together? That would make the everyone a contributor to deco theory

 

[boulderjohn]

I think people missed the point on the use of the word "proven." It implies that the "proven" system is as reliable as it gets, which is why I asked how different "proven" systems disagree with each other.

One of those mentioned as proven is Buhlmann, which was "proven" about 40 years ago, yet, very, very few technical divers today will dive Buhlmann as it was "proven." It is considered to be too dangerous. Erik Baker devised gradient factors as a way to improve that "proven formula," and people carried them to an extreme during the peak of the deep stops era. Then the US Navy's experimental Diving Unit (NEDU) decided that people were stopping too deep, and people started moving the first GF up. Today, divers who are reading the research are frequently using GF-lows of 50-70, which is very different from the deep stop practice.

So, Buhlmann's "proven formula" is pretty much unused today for decompression diving, and people are instead using "unproven" adjustments using GFs. Yet people in this thread seem to be saying that instead of the extremely popular GF trends, people should instead be using Haldane and pure Buhlmann. Curious.

BTW, VPM-B uses conservancy numbers, with +2 and +3 being the most popular. These produce dive profiles in the range considered to be "deep stop," and they are rapidly going out of favor. Those numbers, are designed (in theory) to regulate bubble growth.

Gradient factors (GFs) were created specifically for Buhlmann by Erik Baker, and they control the percentage of Buhlmann's M-Values the diver will reach during ascent, with 100% (pure Buhlmann) generally considered to be too risky. Here is an article by Erik Baker explaining M-Values, and here is one by Kevin Watts that explains gradient factors.

 

[boulderjohn]

I've found this a very good presentation of this topic.

Even though he has this funny accent, Dr. Mitchell explains this topic very well with graphics and charts and stuff.

I linked to that in my article, and Simon was a big help and proofreader for it.

 

[HKGuns]

Didn't notice, but figured it would be of use and topical.

 

[boulderjohn]

Didn't notice, but figured it would be of use and topical.

Very much of use and very topical. As was said of an NFL player a few years ago, he may not be in a class of his own, but it does not take long to call the roll. David Doolette and Neal Pollock would be in that ballpark.

 

[dmaziuk]

Another "thought experiment"!

Given that the vast majority of divers now use some form of dive computer, and given most DC's both log the dive and are able to push that info up to a internet connected PC, don't we already have a way of carrying out the worlds biggest deco study, effectively, almost for free?

At each surfacing event, the computer would pop up some "rating" quesitions, allowing the user to fill in their subjective thoughts on the deco performance and symptoms of DCS, and all that gets fed back to some server somewhere where the mother of all analysis algorythms tries to make sense of it all?

From 3m pool dives, to 300m world records, all the data, together? That would make the everyone a contributor to deco theory

I think they may be trying it with that personal doppler gizmo... google google... O'Dive - The first connected sensor for personalised dives

The problem with getting it off plain computer logs is that vast majority of dives don't result in DCS, such study wouldn't prove anything other than what we already know: dive computers are "generally safe". With doppler bubbles attached you'd at least have some proxy measure of "deco performance" -- inexact as it is.

 

[KenGordon]

Another "thought experiment"!

Given that the vast majority of divers now use some form of dive computer, and given most DC's both log the dive and are able to push that info up to a internet connected PC, don't we already have a way of carrying out the worlds biggest deco study, effectively, almost for free?

At each surfacing event, the computer would pop up some "rating" quesitions, allowing the user to fill in their subjective thoughts on the deco performance and symptoms of DCS, and all that gets fed back to some server somewhere where the mother of all analysis algorythms tries to make sense of it all?

From 3m pool dives, to 300m world records, all the data, together? That would make the everyone a contributor to deco theory

The profile is just bit of the story. Drinking the night before, being dehydrated, doing work at depth, heated vest at the wrong time etc etc all make a difference. Neal Pollock did a talk at a BSAC conference on that sort of thing. The computer will not know those factors.

DAN, Ross H, and the subsurface people (and I guess Suunto, Garmin and Shearwater) all have collections of dive data but without outcomes.