Is UTD still a "fringe" organization?

[StefinSB]

Bottom line; given the number of recreational divers, it's hardly surprising many of them get DCS.

Can you define "many" and state the source?

 

[CAPTAIN SINBAD]

Recent data from Europe indicates that a very large majority of DCS cases with NDL dives happened with divers diving within NDLs. That should be as shocking as saying the overwhelming majority of people who die in Germany are Germans and concluding that Germans are in particular danger in that country. As that study concluded, almost everyone who does NDL diving does so within established limits, so what is actually shocking is that the percentage is not much higher.

No, not at all. According to the data I remember seeing, out of total number of decompression hits, the ones that happened inside NDL were significant. I do not recall the exact number of these hits but it was quite high.

When we are diving here in North Carolina the wrecks are often deeper than 100'. More than half the boat always crashes and falls asleep on the way back. Energy levels on a North Carolina deep charter are drastically different than on a Florida Keys dive charter where we dive a 30 ft reef. Bottom times for the Florida dives are always twice or thrice as long as the 20 minutes on U-352 but collective energy levels on the boat are always different. Why? Because in NC, people get bent. They do not know that they are bent because their computers are showing them clean but they cant walk straight. They attribute their fatigue to exertion they never did and their loss of balance to sea conditions that could be flat as a pool.

I do martial arts and after grappling for 20 minutes in 4 rounds x 5 minutes, with different opponents, I gas out badly. I am sweaty and beat up and struggling to catch my breath. Yet, driving back I never experience the same drowsiness that I experience after returning from a dive on NC dive charters. The tiredness after two repeated single tank dives on U-352 has no relation to the actual exertion I do on those dives. Why should this even be a matter of discussion among technical divers? Doppler research showed us years ago that micro bubbles begin to form inside the body well before we actually reach NDL limits so DCS is not something that magically happens when we cross some clearly market red line but there is a build up of symptoms. It is this fact that most people do not understand. DAN writes the following:

Divers are often surprised when symptoms of DCS develop after dives that were conducted within the limits of their dive computers. It is important to remember, though, that while mathematical models predict outcomes, they do not guarantee them. The fact that a dive was conducted within the limits suggested by a dive computer (or a dive table) does not make a DCS hit “undeserved.” The mathematical algorithms provide guidance that must be evaluated and tempered by a thoughtful diver.

It is this "thoughtful diver" or "thinking diver" that UTD attempts to make by teaching algorithms to the open water diver . UTD mindset is that you are bent on every dive and one way to ease those symptoms of post-dive lethargy is to distribute stop time from deeper depth to shallower in segments. Frankly, I have not done enough dives in that way to personally attest to their effectiveness but I do know people who report that their post dive energy levels are so much better after UTD ascent that they feel like "they were breathing nitrox." There is a certain percentage of people out there who get fatigued within NDL limits on air but when they dive on higher oxygen that fatigue is not there. They do not understand that they were getting bent on air as they are within their NDL so they think that breathing oxygen "raises energy levels." Similarly there is a group out there that practices these half stops and attests to exactly the same effect. I am not fully sure but I believe Lynn, TSandM may also have been one of those who noticed that difference in energy levels after the GUE/UTD style stops.

Is there any hard scientific evidence that such stops offer a superior decompression in general than a computer generated, 3 minutes @ 20 feet? Not at this point but, in the absence of any hard scientific study certain scenarios may be more likely than the others. Adopting them does does not make you less scientific or more scientific. It just shows that you are making decisions in a territory where science has not reached yet. This is why we use the term decompression "theory."

 

[rjack321]

Can you define "many" and state the source?

Not many as in "percentage of recreational dives"
Many as in there are so many more recreational divers that they make up the bulk of DCS cases

Rates I have seen published over the years overall are in the 1/2,500 to 1/6,000 DCS event/dive range. But they are rarely split up or stratified by dive profile. In fact I don't think I have ever seen DCS incident data published by depth or profile in a coherent way.

 

[Wibble]

Can you define "many" and state the source?

Statistics. A curve where you plot the instances of DCS against time (for that profile) then select the point where it is 'n' standard deviations from the norm.

 

[Lorenzoid]

. . . When we are diving here in North Carolina the wrecks are often deeper than 100'. More than half the boat always crashes and falls asleep on the way back. Energy levels on a North Carolina deep charter are drastically different than on a Florida Keys dive charter where we dive a 30 ft reef. Bottom times for the Florida dives are always twice or thrice as long as the 20 minutes on U-352 but collective energy levels on the boat are always different. Why? Because in NC, people get bent. They do not know that they are bent because their computers are showing them clean but they cant walk straight. They attribute their fatigue to exertion they never did and their loss of balance to sea conditions that could be flat as a pool. . . .

We can't completely discount the fact that the NC wreck divers probably awoke before dawn, drove some distance to the dive shop, brought and loaded their own tanks, and had a 3-hour ride out to the wrecks, while in the Florida Keys the divers woke up, had a nice breakfast at the diner, hopped aboard the boat and sat down next to their rental tanks. It's hard to attribute drowsiness on the 3-hour ride back from the NC wrecks entirely to so-called subclinical DCS. I wouldn't doubt that it's a factor, though.

 

[Wibble]

Found empirically that by finishing the last stop shallower than 6m/20' and surfacing very slowly the tiredness seems to be attenuated.

 

[CAPTAIN SINBAD]

We can't completely discount the fact that the NC wreck divers probably awoke before dawn, drove some distance to the dive shop, brought and loaded their own tanks, and had a 3-hour ride out to the wrecks, while in the Florida Keys the divers woke up, had a nice breakfast at the diner, hopped aboard the boat and sat down next to their rental tanks. It's hard to attribute drowsiness on the 3-hour ride back from the NC wrecks entirely to so-called subclinical DCS. I wouldn't doubt that it's a factor, though.

No and we are not discounting that but none of what you mentioned above should cause a whole bunch of people to become flat in the middle of the day ya know.

I have filmed a lot of documentaries on diving and in my crew, there is always the surface cameraman who exerts the most. Then there is the dive team that gets underwater footage. After the dive is over, guess who drives the car and who sleeps in the back seat on the highway? Always!!!

 

[OTF]

Is there any reasonable way to quantify or measure post-dive fatigue? It would make for an interesting study. Shouldn't be too hard to control most of the big variables like workload and sleep.

 

[J-Vo]

Soooo, learning to have enough control in the water to do 1min stops every 10' creates a less fatigued diver. I can get with that.

When I first started diving in the 90s, it was 60'/min ascents and no safety stops. Every dive ended with skin tingles and a very effective beer. Now that I do 30'/min ascents and stay in control the entire dive, safety stops are fully optional and the skin tingles are a thing of the past.

 

[diver42]

When did AG leave UTD, and why?