Alert diver article on Deep Stops

[boulderjohn]

Maybe the agencies don't want to mention deep stops so they can sell nitrox certs.

I'm not so sure it's that so much as inertia ... it's very hard to get training agencies to embrace anything they haven't been teaching for years.

Or it may be because there is not enough clear science behind the concept to have anyone make a commitment. As I read the articles (and I have read quite a few), I have not seen anything clear and definitive yet. I even heard second hand (please correct me if you have better information) that Richard Pyle recently lamented that the only thing in diving named after him (the Pyle Stop) does not work.

 

[Sloth]

I always had an objection to that term ... of course, if you get DCS it's because you violated some limit of your body. The problem is that (a) there are a lot of different variables that determine those limits, and (b) nobody truly understands what the limits are, or how the variables interact to determine them.

Decompression is far from an exact science. That's why there's so much conservatism built into decompression profiles. Saying someone took an "undeserved" DCS hit is like saying someone lost an "undeserved" amount of money at the local casino ... what it really boils down to is you placed a bet on what your body would tolerate and you lost the bet.

... Bob (Grateful Diver)

Is there any research to support the notion that adding more "conservatism" actually decreases DCI risks? Has the rate of divers getting DCI gone down since more conservatism has been added through the years? I seem to recall reading a study about ascent rates being a bigger factor then diving close to NDL in predicting DCI.

The fact is there are still "undeserved" DCI (PFO for example) hits and I dont think you can pad the current models enough to make it practical to totally reduce the risks.

 

[Sloth]

Or it may be because there is not enough clear science behind the concept to have anyone make a commitment. As I read the articles (and I have read quite a few), I have not seen anything clear and definitive yet. I even heard second hand (please correct me if you have better information) that Richard Pyle recently lamented that the only thing in diving named after him (the Pyle Stop) does not work.

Might want to remember that Richard Pyle came up with his deep stops for dives in the 300ft range. Pyle stops have no place in a discussion on recreational deep stops.

Also, he posted in this thread The Deco Stop about where he is wondering if deep stops doesn't work when he does high activity dives. He never says that deep stops doesnt work but he did wonder if it should be a rule for every deep dive.

Unfortunately I havent gotten my copy of alert diver yet but like others have said I tend to look at deep stops more as a way to slow down ascent and not as an excuse to linger at depth. For me deep stops are a way to make sure that I don't haul butt from depth to 15' to do a three minute safety stop. On dives when I went from say 100ft and quickly went to 15ft to do a 3min stop I would usually feel a bit down after a dive. If i do the GUE prescribed 10fpm from the deep stop I would feel better.

 

[boulderjohn]

Has the rate of divers getting DCI gone down since more conservatism has been added through the years?

There is no way to use DCS rates in relation to a supposed added level of conservatism because there are just too many unknowns. There are many different deco theories--are they all getting more conservative or are some more aggressive? Which ones were the people who got bent following? Or were they following one? (See the recent Spiegel Grove incident for an example of a very serious DCS hit on someone who did not seem to have any recognized deco plan at all.)

Studies have to control for variables, and there are just too many variables in the general population to know for sure.

 

[DennisW]

I read the article and it was very interesting. The experts never said to not do deep stops, just that there was no evidence that they lessened the occurrance of DCS. My thought is, if it doesn't hurt, it might help. Just because there is no evidence to date does not mean that one day there may be some study that finds them helpful. Besides, sometimes you see some interesting things hanging out in mid water.

 

[boulderjohn]

Also, he posted in this thread The Deco Stop about where he is wondering if deep stops doesn't work when he does high activity dives. He never says that deep stops doesnt work but he did wonder if it should be a rule for every deep dive.

Good information.

The source I heard it from, though, said he made the statement in the technical diving conference quite a bit after that thread. As I said, my information is hearsay and I would hope to be corrected by more knowledgeable sources. I myself do not feel a great deal of commitment to any position and read all reports with interest.

 

[Sloth]

There is no way to use DCS rates in relation to a supposed added level of conservatism because there are just too many unknowns. There are many different deco theories--are they all getting more conservative or are some more aggressive? Which ones were the people who got bent following? Or were they following one? (See the recent Spiegel Grove incident for an example of a very serious DCS hit on someone who did not seem to have any recognized deco plan at all.)

Studies have to control for variables, and there are just too many variables in the general population to know for sure.

That's kind of my point. Some people dont like the term undeserved hit thinking that if they follow the rules they will be ok. Bottom line there are too many variables to ever say with 100% certain that if you only stay down so long or ascend no faster then X you wont get a DCS.

Honestly though DCS is like what number three on diving accidents? Number one drowning - people panic or have a heart attack and drown. Number two AGE - people ascending to fast. DCS is so unlikely I don't really understand why people spend so much time worrying about it.

 

[gcbryan]

Since most everything bad in diving happens on the way up I see no reason not to do a deep stop (how ever you define that).

It's like arguing that you don't need to pause for a moment as you cross the street as long as you look both ways first. What is the harm even if there are no studies?

Going up too fast is not a good thing so slow down.

It's about nitrogen absorption in non-critical tissues vs reduced bubble growth. I'm more interested in the later at that point in the dive.

 

[JeffG]

Maybe, but I am getting older and if a deep stop lets me get away with some more aggressive diving, then I am going to do it, even if DAN thinks it is not necessary.

I agree and with the diving you do, I think deep stops are appropriate. (I'm a believer of them too). But your diving and the diving that DAN is talking about are 2 different things.

 

[dumpsterDiver]

That's kind of my point. Some people dont like the term undeserved hit thinking that if they follow the rules they will be ok. Bottom line there are too many variables to ever say with 100% certain that if you only stay down so long or ascend no faster then X you wont get a DCS.

Honestly though DCS is like what number three on diving accidents? Number one drowning - people panic or have a heart attack and drown. Number two AGE - people ascending to fast. DCS is so unlikely I don't really understand why people spend so much time worrying about it.[/QUOTE]


For the experienced diver it is a big worry. Most of the other factors are uncontrollable or unknowable. Maybe I WILL totally panic underwater, but I try to prepare myself to prevent it.

I've seen a lot of people get bent and a few get permanently disabled. When you see that and maybe been bent yourself a few times, this crap becomes a big deal. It is for the most part preventable and when it does occur it is very important to have oxygen available. To say that it is so unlikely that it is unimportant is unwise. The risk is not that high, but the consequences are too severe to ignore.