Padi Advanced OW - Deep stops??

[rjack321]

Yes. Did you?

Did you notice how it went from Haldane's half-pressure to "half depth" to table 4 where the stops are at 15m after max depth of 25m?

What is the relationship between Dr. Marroni's study and any of the tables presented on that page?

Did you notice this bit: "the missing link of this research is the unknown relationship between Doppler-detectable bubbles and neurological DCS. For the moment, it is our hope that by eliminating the 30 percent so-called silent bubbles in the heart, we will also be stopping their occurrence in the spinal cord too. More research is needed in this regard."

I also read a few computer manuals. Google was able to find me a page where someone claims PZ+ uses half depth for its "deep stop" -- it's on the Internet so it must be true. Didn't see any manual spelling out what their "deep stop feature" actually does.

Like I said, let the popcorn pop.

Sigh
NAUI pragmatically set their "deep stop" at 1/2 the max depth.
The Marroni data are at the bottom of the page, do you want a link to the actual paper in UHMS?

Yeah cause it's unethical to actually bend divers intentionally. And a 1 in thousands natural hit rate is going to require far more dives to test differences in actual DCS rates than can be accomplished with Doppler testing as a surrogate.

Several people have said "no agency does recreational deep stops on a deep course" and that they are "antiquated" if they do. Neither are correct statements.

 

[DevonDiver]

NAUI is doing a whopping 1min at 1/2 the depth based on a DAN bubble study by Maronni. Completely different beast as its technically a no stop dive in the first place.
DAN | News

Hate to break this to you....

DAN - Deep Stops by Peter Nenoble (2010)

If you look at the comments in that, later, article - you can see that the issue of deep stops is far from wholeheartedly supported. The general attitude is that they don't prove any significant benefit. That's why other agencies are unlikely to be 'teaching' them at this stage.

Of course, the big argument regarding deep stops is centered on technical diving - and the issue of slow tissue on-gassing on deep stops that, in all likelihood, are conducted deeper that recreational divers should even reach.

Nonetheless, most agencies formally teach practices that are proven necessary/effective. Shallow stops are proven beneficial. Deep stops.... after a decade... have not been.

 

[wetb4igetinthewater]

You'd be surprised how your goals change. When I first started diving, I didn't want to go pro or get into technical diving. But then I got hooked....

 

[rjack321]

Hate to break this to you....

View attachment 381692
DAN - Deep Stops by Peter Nenoble (2010)

If you look at the comments in that, later, article - you can see that the issue of deep stops is far from wholeheartedly supported. The general attitude is that they don't prove any significant benefit. That's why other agencies are unlikely to be 'teaching' them at this stage.

Of course, the big argument regarding deep stops is centered on technical diving - and the issue of slow tissue on-gassing on deep stops that, in all likelihood, are conducted deeper that recreational divers should even reach.

Nonetheless, most agencies formally teach practices that are proven necessary/effective. Shallow stops are proven beneficial. Deep stops.... after a decade... have not been.

NAUI still does them for their "deep" class and the Marroni study was/is their basis. Contentious, sure, but not unethical or ridiculous. Even Simon will tell you 1 minute is essentially nothing relevant for slow tissues - presumably the Doppler score differences being fast tissues since they were collected soon after surfacing anyway.

 

[packrat12]

Here is yet another well written article discounting the benefits of a Deep Stops. The question I have is "why stay deeper and take on more N2 loading?". It is better to get out of the on-gas depths when not needed!

From the NEDU (Navy Experimental Diving Unit):
Redistribution of Decompression Stop Time From Shallow to Deep Stops Increases Incidence of Decompression Sickness in Air Decompression Dives

www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA561618

 

[DevonDiver]

Contentious, sure, but not unethical or ridiculous. .

Agreed. I was merely redressing a claim that teaching deep stops was "more complete".

There's nothing 'incomplete' about not incorporating contentious practices into a syllabus.

Personally, I think there's a far better case for shallow staged safety stops, than there is for deep stops.

 

[rjack321]

Agreed. I was merely redressing a claim that teaching deep stops was "more complete".

There's nothing 'incomplete' about not incorporating contentious practices into a syllabus.

Personally, I think there's a far better case for shallow staged safety stops, than there is for deep stops.

Contentious topics are better (briefly) included in AOW classes, cause no AOW student is going to make it through the thousands of pages of hokum on the deep stop topic here, or on RBW, or on CCRx...

 

[Eric T Lewis]

I am a former commercial diver. Did deep air and even deeper gas diving. We followed the USN Dive tables. They were invented using young very fit Navy divers.

We called the computers bend-o-matics. There is no way to increase bottom time and cheat physics. Boyle's law is king. The people selling the computers don't care if you get bent, they just want your money.

Read all of the disclaimers that the dive computer companies stuff in the box.

Offshore we had decompression chambers at the ready to treat dcs. On a pleasure boat you do not.

An extra five or ten minutes bottom time are not worth the risk of injury.

 

[tbone1004]

In my opinion don't buy something too expensive and complex. Now that you are taking your time to get comfortable underwater, I think it will be best for you to buy something that is easy to use, read and has a big display rather than buying a high tech gadget that is complex to use and makes you wonder what is what. Look for something with big numbers and high contrast colors, buy something that can do just what you need, no more no less, but after all the choice is yours.

easy to use, easy to read, big display, big numbers, high contrast. Sounds like the Perdix in recreational nitrox mode.

 

[DrGonzo]

In AOW, I thought the recommendation was to do a 1 minute stop at half the deepest depth. Eg if you first went to 30m then you stop for 1 min at 15m somewhere during the total dive time. However, you can just swim along at 15m for 1 min.
I then do 3 mins at 6m, 1 min at 3 metres and surface.