Deep stops, Pyle stops, Gradient Factor

[voidware]

I have heard plenty about all of the above, but I was wondering what the theory was behind their effectiveness how I should implent such conservativism factors into my profile. This is coming from a rec diver, hoping to get into tec diving soon.

thanks,
brandon

 

[Lost Yooper]

Greetings,

That's kind of a loaded question actually. There's a lot reading and understanding that has to be done to get a decent understanding of what's going on. You really should have a decent idea of what is going on before attempting some of this stuff. It doesn't take long to learn it, really.
There are things you can do as a recreational diver to help alleviate sub DCS in your decompression procedures. First and foremost, always implement slow ascents (less than 30fpm) -- especially a slow ascent during the last 30' or so. Second, stop for a few seconds (about 30secs or so) every ten feet starting at 80% of the dive profile. Third, use nitrox (eventually trimix) and stay away from air if possible. Fourth, avoid post dive physical exertion. Fifth, hydrate yourself prior to diving.

As for the actual theory behind deep stops there are a few authors and divers to pay attention to: Maiken, Baker, Weinke, Younte, Hamilton, Irvine, Jablonski, and even Pyle to name some good ones. Here's some links to some of these guy's papers:

Maiken’s Page -- Great article describing bubble mechanics.
http://www.decompression.org/maiken/Bubble_Decompression_Strategies.htm

Baker’s page -- Lots of theory to screw your brain up for a while .
http://www.decompression.org/baker/home.htm

Gudmunsen’s Page -- Dangers of Deep Air -- Nice eye opener.
http://www.fotofixer.com/1deepDivingonAir.htm

Pyle’s page (Nice basic understanding of what is going on, but I don't care much for his way of implementing deep stops).
http://www.cisatlantic.com/trimix/pile/deepstops.html

V Planner -- Nice, easy to use deco software (free) that uses the VPM deco model and deep stops.
http://www.coastnet.com/~powercheck/zplanner/index.html

GAP -- Another deep stop deco software.
http://www.gap-software.com/

GUE’s Deco Planner -- A well renowned and proven deep stop deco software.
http://www.gue.com/decoplanner/

There's a lot of reading for ya. I especially like Maiken's and Baker's papers regarding the physiology of deep stops and bubble formation.

Take care.

Mike

 

[daylight]

First of all, Welcome to the board. There are a lot of great folks here like Lost Yooper. They will also take the time to provide a comprehensive answer to a question.

There isn't much to add to the info Lost Yooper provided. DAN has been reaching the same conclusion that the subject matter experts referenced. You make want to look at some of the articles Dr. Bennett from DAN has been publishing.

DSAO

 

[voidware]

Thanks for your help guys.

I have been playing with some of those decompression programs (mostly conducting dives on 100% nitrogen to about 1600ft and then trying to decompress from them, but, alas, I digress). Since I am most definately not sufficiently trained to pull of a mandatory decompression dive, I do not attempt to try to use them in reality. However, I was wondering which program you guys use? (with all the DIR, I bet its decoplanner) and if they are actually safe and functional (case-in-point: the freeware ones).

Thanks again guys. Soon enough I hope to join your ranks.
brandon

 

[Rick Murchison]

That is a very nice list, LY.
Thanks a bunch.
Rick

 

[Arduous]

Hi voidware:

Decompression diving requires proper instruction, this is not something that you want to take lightly. It’s not to be fooled with. Though it’s not rocket science, attempting it with out proper instruction and knowledge can have fatal results. Please don’t go out and buy a decompression software package and then attempt to dive on the profiles it provides. These programs are good, I use them myself ( Abyss from www.abysmal.com )
However one needs to understand the principles behind the whys before attempting to apply the hows.

Dive Safe ……………….Arduous

 

[Lost Yooper]

Voidware,

I have used a lot of different decompression techniques from Navy tables and diving computers to deco program generated tables. You will find that most of the deco programs that use deep stop alogorithms often spit out somewhat similar deco profiles for relatively basic deco dives.

I haven't used Deco Planner, but have seen many of their profiles. The users of DP seem to be quite happy with it. I've played with GAP a little bit, but most of my dives were using modified Z Planner profiles. I've since changed to V Planner (same author as Z Planner, but uses VPM), but due to its relatively recent release, I haven't actually dove any of its profiles. I have played with it a bunch and am confident it will work nicely for my type of diving.
The biggest problem with most deco software and especially dive computers is they are inherently too conservative (unnecessarily conservative). V Planner seems to spit out very nice profiles, but it will depend on how I feel afterwards for me to determine how it will work out. None of these program are 100% correct, and there's a few things one can do to "trick" the program to increase safety and offgassing (not that I would do or recommend such things ).

I've tried Pyle stops and other things too, but didn't care for them too much. One thing is for certain though, deep stops (in any form) make me feel a bunch better after a dive. Using proper deco gasses makes a huge difference as well.

Just make sure you have good understanding of what is going on before diving into this stuff. It's not difficult to learn. Keep in mind that in many circles using deep stops is still not fully accepted. Just this pass summer I was on a charter boat with a IANTD trimix instructor (with "credentials" up the wazoo) with his student, and deep stops weren't even mentioned much less used (his student felt like crap too). Like I often say, being taught wrong can be worse than anything. Keep this in mind -- formal training doesn't necessarily equal proper training. Make sure you do your own research.

Take care.

Mike

 

[Dr Deco]

Dear voidware:

The question has been answered in part by the responders above. Good points.

The decompression schedules created by these programs are all performed in the water and divers loose many of the tissue nuclei generated by walking. Since military and commercial divers are decompressed in a chamber, they all are on their feet to some degree. It is therefore difficult to compare the results technical diver decompression (with buoyant divers in the water) and divers in a chamber. We found at NASA that there were big differences in the decompression outcome depending on whether the subjects were walking or not. (This resulted in the way tests were performed since, in space, no one really walks.)

My question is, why do virtually all cases of DCS appear after the divers are on the surface (and on their feet)? I believe that musculoskeletal stress plays a big role in this activity. Therefore, I do not know how near (or far) the deco schedules are to the optimum without some type of controlled study. Because of costs, such studies will not be performed. This is not to say that the deco schedules are faulty, but only to say what is the exact reasons) for their effectiveness. To a research scientist, such questions are important.

It is my understanding from many respondents on this and other forums, that the deep stops are important insofar as how the diver feels. It is certainly true that slower ascents will result in reduced growth of bubbles. This can be easily seen when one slowly opens a bottle of a carbonated beverage. When slowly opened, few bubbles form. This is not because the carbon dioxide escapes from the quid, but rather because little bubbles (nuclei) stay small with a high internal Laplace pressure. Releasing the pressure quickly allows these to spring to a larger diameter by Boyle’s law expansion, the Laplace pressure is now smaller and they grow. Rapid ascents produce a similar effect in your body.

Dr Deco :doctor:

 

[The Iceni]

Dear Voidware,

I too am interested in the principles behind deep stops on a more basic level and admit to a certain amount of confusion.

It seems deep stops do help with the elimination of microbubbles but there is a down side. Any period at relative depth will be seen by the slower tissue compartments (which remain incompletely saturated at the completion of bottom time) as an extention to the period of on-gassing and will therefore be relatively more saturated after the deep stop, than before.

I assume, and stand to be corrected, that this will not adversely influence the total in-water decompression schedule, but without a clearer understanding of what happens in practice I am not really sure.

I suspect there is a trade off between microbubble elimination and a marginally higher risk of DCI in the slower tissue compartments when deep stops are made.

Am I right, Dr Deco?

 

[BILLB]

I have one theory about Tech/cave diving. All dives must be PERFECTLY executed. Mistakes are not allowed. Every dive must be a perfect dive. It sound tough, but if you do not follow all the rules and training you die.

If this is not enought to discourage you, then get the all the training required BEFORE even thinking about deep, staged decompression diving.

Bruce Wineke ,et al RGBM tables have not shown up her in any discussion. NAUI TECH has adopted them. Anybody have anything to say?