Suspected Nitrogen Narcosis... And Decompression.
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BDSC
Contributor
Bob DBF
Contributor
USN test of deep stops, shows a higher incidence of DCS with deep stops.
http://www.johnchatterton.com/wp-content/uploads/2013/03/NEDU_TR_2011-06.pdf
Bob
BDSC
Contributor
Thanks Bob.
That goes along with what the guys over at DAN headquarters told me. No benefit and perhaps harmful from the study you posted. Maybe that's why you don't hear much about them anymore.
That goes along with what the guys over at DAN headquarters told me. No benefit and perhaps harmful from the study you posted. Maybe that's why you don't hear much about them anymore.
There was an extensive and contentious discussion on deep stops on ScubaBoard very recently. Yes, a lot of people are looking at the research and moving quickly away from them. On the other hand, a lot of people still believe in them.
When looking at issues like that and judging our personal experienes, we have to be careful of committing the post hoc fallacy--if I did something and then later something else happened, what I did first must have caused what happened after. It might be true, but it might not.
Let's say I go on a very strict diet and combine it with heavy exercise. I am thus consuming far fewer calories per day than I am using. An interesting part of my diet is that I choose to reward myself each day with a hot fudge sundae, with the rest of my diet so severe that I am still low in total calories. If I lose weight (as I should), I might conclude that hot fudge sundaes help you lose weight. That is an example of post hoc thinking. It is similar to the belief that sacrificing a virgin early in the spring will bring the rains needed to produce a healthy crop.
Let's say you use a good, solid decompression plan and include deep stops. You never get bent. How can you tell if the deep stops 1) improved the quality of the plan, making the plan better, 2) had no impact on the plan whatsoever, or 3) made things worse, but not worse enough to overcome the quality of the rest of the plan (like a hot fudge sundae on a diet)?
A good, scientific study has to find a way to isolate the individual factors within a dive plan so that you know you are studying that part of the plan without it being impacted by other, unrelated parts.
When looking at issues like that and judging our personal experienes, we have to be careful of committing the post hoc fallacy--if I did something and then later something else happened, what I did first must have caused what happened after. It might be true, but it might not.
Let's say I go on a very strict diet and combine it with heavy exercise. I am thus consuming far fewer calories per day than I am using. An interesting part of my diet is that I choose to reward myself each day with a hot fudge sundae, with the rest of my diet so severe that I am still low in total calories. If I lose weight (as I should), I might conclude that hot fudge sundaes help you lose weight. That is an example of post hoc thinking. It is similar to the belief that sacrificing a virgin early in the spring will bring the rains needed to produce a healthy crop.
Let's say you use a good, solid decompression plan and include deep stops. You never get bent. How can you tell if the deep stops 1) improved the quality of the plan, making the plan better, 2) had no impact on the plan whatsoever, or 3) made things worse, but not worse enough to overcome the quality of the rest of the plan (like a hot fudge sundae on a diet)?
A good, scientific study has to find a way to isolate the individual factors within a dive plan so that you know you are studying that part of the plan without it being impacted by other, unrelated parts.
thirdparty
Registered
Yes, this is the difficulty in the real world application of scientific studies and the problem with spurious correlation that lots of people live by..."I've been doing it this way for years..."
OP
timz
Contributor
Something just came to my mind while discussing the deep stop and decompression.
Let say. They really proved that having a deep stop actually increase the risk of deco. Will all major agencies like SSI, SDI, PADI and etc will reprint their books?
Will all the Dive Computer rewrite their program and update their firmware according to the latest result?
It's a big industry and alot of things has to ben thrown away.
Let say. They really proved that having a deep stop actually increase the risk of deco. Will all major agencies like SSI, SDI, PADI and etc will reprint their books?
Will all the Dive Computer rewrite their program and update their firmware according to the latest result?
It's a big industry and alot of things has to ben thrown away.
It is indeed a risk, and books have had to be rewritten in the past. As for deep stops, most agencies that I know of never really got all that much on the bandwagon and so do not have all that much to do.
The PADI Trimix course was written during the height of the deep stop movement, and it has quite a bit of deep stop material and even requirements in it related to that. On the other hand, it also has a section on the importance of keeping current with the latest research, saying clearly that thinking changes due to that research. Having those two things in the same course gives me a great opportunity to show deep stops as an example of why it is important to keep up with those changes. PADI does not talk about deep stops in courses before trimix. It is not mentioned at the recreational level of its training, so nothing needs to be changed.
The TDI Decompression Procedures course does not require students to use a specific dive planning program, and it does not talk about deep stops, but it does focus instruction on V-Planner, which will tend to give deeper stops than many other software programs. Ross Hemingway, the creator of V-Planner, is very critical of the movement away from deep stops and still very much believes in them. He was a major participant in the thread mentioned earlier. I have not heard any talk of TDI changing its approach.
Part of my past includes training through UTD, which bases its dive profiles on Ratio Deco. That system was designed, too, at the height of the deep stop movement, and its first stop is very deep when compared to many other programs. I believe they are still committed to it.
I was once under the impression that NAUI had committed to doing deep stops in its recreational program, but someone else told me that was not true. I don't know. NAUI's tech program was originally designed by the man who later created UTD, but I don't know if his commitment to deep stops is part of the current program.
I don't know much about other agencies. I suspect that most of them had very little to say in favor of deep stops, so they have very little to change.
BDSC
Contributor
Can you link to that thread?
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