Looking for clarity

[Musashib]

This is in regards to the second safety stop on deep dives.As a deep diver I due prefer to make the second stop. According to the PADI Deep Diver Manual the words "Over the past few years" and the word Recommended have been used. I've had several discussions with various Instructors here in Japan and although surprisingly reading this have deemed the stop unnecessary for the Following reasons.
1.The words used in the manual stated above.
2.The fact that the body is taking on Nitrogen at the stated depth of 18-20
meters not releasing.
3. And the fact that it hasn't been integrated in student training.
4. And a common fact that if its not in writing it can't be implemented.

I have been made aware that some countries have a delayed time frame when it comes to updating and translating manuals. I don't want to think but must accept the fact that some instructors might not review or keep up to date on some issues but as someone entering the DM course I just need clarity on this issue. Any information or references would greatly be appreciated.

 

[boulderjohn]

I have to admit first of all that I did not understand your question perfectly, but I will try to give an answer that you might find helpful.

Despite all the research and all the years, decompression theory is still hotly debated, and there is not a lot that anyone can say with absolute certainty. None of the latest theories have been adequately studied to determine their effectiveness, in my opinion.

As far as deep stops are concerned, that is really a debatable point. A recent (2008) DAN conference raised new questions about it. The problem is that some of the studies done contradict other studies. There are studies that support the use of deep stops, and there are studies that do not.

I have done a lot of study in this area in the last year, and I am not sure what I would write if I were in charge of putting out a new manual at this time. There is a good chance that anything you write will go out the window in another year or so. I am pretty sure that is why you are not seeing anyone rushing out to publish new guidelines.

That's the bad news.

The good news is that it really doesn't seem to matter all that much. Just about every system that has been in place for reasonably deep depths for long enough to have any kind of track record is working pretty well. The risk of DCS rounds off to 0%. (My definition of "reasonably deep" is intentionally vague, extending a bit past no decompression diving into minor decompression diving.) There is even one system (which I will not name to avoid a flame war) that I feel is based on flawed theory and still produces pretty good results.

When I talk to students, I tell them essentially what I just wrote, although in more detail. I describe the main theories, and I give my opinions. I am sure to tell them that my opinions could change if I am presented with more studies.

 

[Musashib]

Hi Thanks for your reply.
I guess I didn't really get to the point. I was just curious if the stop was being implemented in the states. You're so right about the debates and research still ongoing. I think it's a very interesting point that the body is still taking on Nitrogen at that depth.
I guess we'll see. Thank You

 

[Bubbletrubble]

I guess I didn't really get to the point. I was just curious if the stop was being implemented in the states.

To answer your question, some dive instruction agencies in the U.S. are teaching divers to do "deep stops" (at some depth below 15-20 fsw). There is not 100% consensus on the duration and depth of those stop(s).

I recommend doing your own research into the evidence that supports the use of deep stops. The Rubicon Foundation Archive is a wonderful resource for this.

 

[Musashib]

Thank you so much. I have spent hours and hours going through Rubicon's studies and materials. Thanks so much for the info.