"re-assessing deco profiles and deep stops", plus other bits..

Mark Chase said:
Totaly agree on tthe 100/100 being agressive but I am wondering if we should be running 75/75 tather than 30/75?
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AIUI, there are tissues with half-times of a few minutes to several hours. It takes six half-times to reach saturation. So some tissues will be saturated within 10 minutes of hitting the bottom, wheras others will have barely started to on gas. These on-gassing slow tissues mean that unnecessary deep stops lengthen your shallow stop deco. So removing a minute or two shallow and putting it deep makes your dive more risky.

====

So looking at this VERY VERY simplistically. [1]

Consider a diver diving to 90m (10 bar) with two tissues:
Fast tissue A has a half-time of 1 minute.
Slow tissue B has a half-time of 3 hours
The allowable supersaturation is a factor of two [2]

BOTTOM PHASE
The diver is at 90m dive for 30 minutes.
- Tissue A - 10 bar (fully saturated)
- Tissue B - 1/6 half-life passed, so 15% saturated, so 1.5 bar.

FIRST STOP
- Diver ascends instantly [3] and stops at 40m (5 bar)
Tissue A - 10 bar - ie twice ambient
Tissue B - 1.5 bar - less than ambient so ON GASSING
The diver has to stop here as the fast tissue is twice ambient (which I defined to be the super-saturation limit up there ^^^^^), any more and they would break the ceiling and get bent.

THE DIVER WAITS FOR 1 MINUTE
Tissue A - 7.5 bar
Tissue B - A smidgen over 1.5 bar - and On gassing

NEXT STOP AT 27.5m FOR ONE MINUTE
- Limited by Tissue A - which is at 7.5bar, so allowable pressure is (7.5bar /2) = 3.75 bar, so 27.5m
- Tissue B - a bit over 1.5 - and still on gassing

NEXT STOP AT xxx
- Again limited by Tissue A
- Tissue B - and still on gassing

NEXT STOP AT xxx
- Again limited by Tissue A
- Tissue B - still on gassing

Etc etc.

Eventually the diver will reach a shallow enough stop where Tissue B is controlling the deco. In this example, it would be 1.5 bar x 2; so 3 bar, so 20m.

=========

The point of all of this is that deep stops, while necessary for the quick tissues, add deco to the slow tissues. Tissue B is ongassing all the way through those deep stops.

So if you do additional deep stops, you must add time to your shallow stops to compensate. This is why I've never been in favour of those people who use ratio deco and DOTF to "shaping the curve" by removing shallow stops and adding deep stops.

Personally I believe in adding deep stops AND recognising this makes my shallow stops longer. My computer calculates this for me.

Janos

[1] - Someone is bound to chip in with the real numbers, but it's not that relevant.

[2] - Ie they can have a tissue tension of twice ambient. In reality it's more like 1.6; and depends on depth, and your GF.

[3] - In reality they would ascend slower than "instantly" - so tissues would off gas
 
anarchista said:
During the ascent free tissue compartments continues to saturate, and then control the decompression beneath the surface, I said it.

GLOC will answer later
http://rebreathers.pl/forum/download.php?id=106

greet rc
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Thanks. English not that clear. Do you mean that link answers my questions regarding papers being referenced or do you mean you are going to answer my question later? The link you gave has the newest research as the late 1980s, I thought you were referring to new research covering this material?

Regards
 
You do not present any publications, to support argument.
Do you belong to a scientific society, involved in diving medicine or hyperbaric technique?
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I'm a member of a dive club, does that count? Oh, and I did do a few years of physics in uni. I'll confess to being weak on statistics, but I've never had much trouble with diving papers. That's all irrelevant, though, because what matters is what one is saying and whether they can back it up. Not who's saying it. You'd know that if you had a rational (or scientific) mind, as opposed to flashing a membership card. More on that later.

All I said is:

There are already several models of tissue developed, many decompression took place. They are accurate enough to know that deep stops will extend the total decompression time, it will also be safer.
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I haven't heard or read any evidence of that.
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I don't have to prove anything, that's a fact. Besides, rebuttal is easy: you just have to put up a link to a paper, or an abstract, that presents such evidence. Which you chose not to do.

Now, if you're looking for studies that suggests that deep stop may not be good, which wasn't what I said, but anyway, here you go:

Going back to credentials. There are people on this forum who have the "street cred" to just make assertions and have everyone take those assertions seriously. That's because everyone else know they think straight, have the experience and/or evidence to back up those claims, and that it will be provided if requested.

Obviously I'm not one of them, but the key thing here is, neither are you. In fact, due to your continued reluctance to back up anything you say (besides "somebody said"), your tendency to move the goal posts or completely change subject as soon as somebody has a valid criticism of your claims, your tendency also to resort to ad-hominems (even if ignoring insults as poor translation), and the general dishonesty of demanding of others to prove their claims while not doing any of that yourself, I'm starting to believe you're just another internet troll.

Sincere apologies to the other members of the forum for the tone of this post.

Regards,

Matthieu
 
GLOC said:
However, saying that members of this forum aren't in the league as AP and Aqua Lung Military is not particularly helpful. The majority of those on this forum are day to day users of recreational diving equipment which has been developed on a shoe-string budget compared to the Military, however, the risks are still the same (if not more because they do not have the same support/oversight structure as the military).

Providing additional information is helpful to all, and I know that there are issues with posting whole papers which are in journals (I've fallen foul of that already, by accident) but there is nothing wrong with posting the title of the paper/journal so that those with access to the journals can download them accordingly.

In your last sentence, do you mean the ppO2 is stabilised IN the ascent, or the ascent stabilising the ascent. Slightly different meanings. I think you mean the first one.

Regards
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I asked, for a show his of cards.

Budget is a helpful thing, the technical and scientific support, but need ideas. It does not have a monopoly in the companies producing equipment for the military.

It's in your profile inquiry, which topics you need.
http://rebreathers.pl/forum/download.php?id=106
I left that position signature publishing, can be found.
The technique of pure gases is difficult, because it dealt with the military companies. I stated how to search for information about the author's achievements, stated the link PHR.
http://www.ccrexplorers.com/showthread.php?t=14504
There are three solutions 2, I gained the status of a patent (2005, 2008). The third (2010) is available to producers and the scientific community.

It is a stable ppO2 during the ascent, free and very fast.
This is in the first patent, or other regimen of oxygen, which provides constant dose at each depth, and the low pressure a typical one 1 stage.

GLOC said:
I am a member of both UHMS and SPUMS. Can you send me the links?
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To which the Society you have been invited?

Janos said:
NEXT STOP AT 27.5m FOR ONE MINUTE
- Limited by Tissue A - which is at 7.5bar, so allowable pressure is (7.5bar /2) = 3.75 bar, so 27.5m
- Tissue B - a bit over 1.5 - and still on gassing

NEXT STOP AT xxx
- Again limited by Tissue A
- Tissue B - and still on gassing

NEXT STOP AT xxx
- Again limited by Tissue A
- Tissue B - still on gassing
Click to expand...

Janos, you can know better what simplification is necessary.
But here it went too far, there are 16 compartments in the model Buhlmann, with one gas. How tissue decompression stop control over the time, interval controls the next tissue. But often the beginning begins and ends with one control next decompression tissue. Similarly, the shallow accelerated oxygen. Introduction GF reduces the maximum supersaturation, therefore go deeper decompression stops.

greet rc
 
[Moderation hat on]

Someone reported a post in this thread. I can't see anything too bad, but could I ask people to keep the debate about facts and not about people's 'credentials' - if they're talking crap, then feel free to point out what they said is wrong - but just because I once stayed in a Holiday Inn, it doesn't mean my viewpoint is worth more or less than anyone else's.

Cheers,
Janos

[Moderation hat off]
 
Janos said:
[Moderation hat on]

Someone reported a post in this thread. I can't see anything too bad, but could I ask people to keep the debate about facts and not about people's 'credentials' - if they're talking crap, then feel free to point out what they said is wrong - but just because I once stayed in a Holiday Inn, it doesn't mean my viewpoint is worth more or less than anyone else's.

Cheers,
Janos

[Moderation hat off]
Click to expand...

:agree: spot on.
 
emmbee said:
Now, if you're looking for studies that suggests that deep stop may not be good, which wasn't what I said, but anyway, here you go:
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There are also reports which is noticed advantage of deep stops.
Extraction of information requires write requests to Dr. med J.Kot because it works at the university and cures, it will respond when he had time.
Therefore, there has to be fast.
Discuss these issues at a meeting of the Kalatówki CMAS instructors.

You did not answer, why the technology pure gases, is bad.

rc greet
 
Just catching up with this thread. For along time I've been doing deep stops - I simply understand these stops to be ones that are deeper than the non-GF Buhlmann.

GF based deep-stops just add to the shallow stops, and I've long thought that's where the good feeling comes from. For example 30mins/70m is:

GF15/85 - 120 minute run with a first stop at 45m (last 2 stops: 9m/10mins, 6m/44mins)
GF100/100 - 90 minute run with first stop at 24m (last 2 stops: 9m/8mins, 6m/33mins)

Is this what we mean nowadays by deep-stops or do they mean something else?

I think I'd side with Mark - they GFlo could be moved a fair chunk higher and we'd (probably) still get that feel good factor.

I also agree with Janos - do the crime do the time, it's no hardship (mostly).

Back OT - eCCR for me all the way; why have a dog and bark yourself.

Cheers
Matt.
 
There are also reports which is noticed advantage of deep stops.
Extraction of information requires write requests to Dr. med J.Kot because it works at the university and cures, it will respond when he had time.
Therefore, there has to be fast.
Discuss these issues at a meeting of the Kalatówki CMAS instructors.
Click to expand...

Well, I look forward to reading that.

You did not answer, why the technology pure gases, is bad.
Click to expand...

I said that using diluent (so in the context of a CCR) with no oxygen in it didn't solve any issue on the descent, and that it raised other problems.

And I said it was generally considered a bad idea.

Well, obviously it's not going to solve anything on the bottom or on the ascent, either, because at this point you're not using the dil anyway, so what's in it is irrelevant. And I've never heard anyone advocate it (although obviously I'm just mod 1, so...), and none of the deep divers I know do that, and since it's their life if they get it wrong, I'll go with them on that.

You stated you had solutions for the problem of doing a dil flush, but since you didn't elaborate, I, we, can't comment. And again a pure N2/He dil does not solve anything for a CCR. That I can see, anyway.

Having said that, it's not clear what you mean by pure gases. I was talking about N2/He dil and you didn't correct me. But did you actually mean one cylinder of N2 and another of He?

Now I could see the point in that. Theoretically. I know some people lie to their computer and tell it they're now using air as diluent on the ascent, and follow that deco profile to get out of the water faster. It works because, well first and foremost because they're unbendable or something, they're well prepared, and the deco computer is too conservative, and it works because the computer thinks the inspired ppHe is now much lower (well, 0), so it computes that outgassing to be faster, and that's what leading. It follows that if you had pure gases, and the ability to change your inert mix during the dive, you'd realise those gains (or better, even), but, err, "for real". Theoretically. And you'd have to take into account isobaric counter-diffusion. I don't know anyone plugging in a different dil during the ascent either, even though it could readily be done.

Later, in relation to this part of the thread you also mentioned that ppO2 levels were a problem with SCR on the ascent. Well, yeah. So are you talking about an SCR with 3 cylinders (O2, N2, He), then?

Cheers,

Matthieu
 
emmbee said:
I said that using diluent (so in the context of a CCR) with no oxygen in it didn't solve any issue on the descent, and that it raised other problems.

And I said it was generally considered a bad idea.

Well, obviously it's not going to solve anything on the bottom or on the ascent, either, because at this point you're not using the dil anyway, so what's in it is irrelevant. And I've never heard anyone advocate it (although obviously I'm just mod 1, so...), and none of the deep divers I know do that, and since it's their life if they get it wrong, I'll go with them on that.

You stated you had solutions for the problem of doing a dil flush, but since you didn't elaborate, I, we, can't comment. And again a pure N2/He dil does not solve anything for a CCR. That I can see, anyway.

Having said that, it's not clear what you mean by pure gases. I was talking about N2/He dil and you didn't correct me. But did you actually mean one cylinder of N2 and another of He?

Now I could see the point in that. Theoretically. I know some people lie to their computer and tell it they're now using air as diluent on the ascent, and follow that deco profile to get out of the water faster. It works because, well first and foremost because they're unbendable or something, they're well prepared, and the deco computer is too conservative, and it works because the computer thinks the inspired ppHe is now much lower (well, 0), so it computes that outgassing to be faster, and that's what leading. It follows that if you had pure gases, and the ability to change your inert mix during the dive, you'd realise those gains (or better, even), but, err, "for real". Theoretically. And you'd have to take into account isobaric counter-diffusion. I don't know anyone plugging in a different dil during the ascent either, even though it could readily be done.

Later, in relation to this part of the thread you also mentioned that ppO2 levels were a problem with SCR on the ascent. Well, yeah. So are you talking about an SCR with 3 cylinders (O2, N2, He), then?
Click to expand...

"This is a bad idea, because it is a bad idea."
You said something about studying physics, speak in the language of mathematical analysis.

The partial pressure is constant at the immersion, there is no increase associated with the provision of additional quantities, along with the diluent. Therefore there is no need to do a circus ppO2 reduced at the beginning of the dive.
Which is advantageous from the point of view of Prof. Gulyar, for the rapid compression of hypoxia.

You can use anaerobic linear combination of inert gases, even the first patent gives you the ability to mix gas with the proper ppO2 not depending on the chemical composition. Does not use the technique CMF.

Problems with drop ppO2 ascent of SCR have been resolved, I know three such solutions 2 available in the patent literature. The CCR need for the device with a higher degree of complexity. Or measurement of galvanic oxygen sensors and electronics, or the measurement of depth and dh/dt (h-depth). Additionally, the program which calculates and solenoid walve which starts at the specified time, different at different depths. This is due to the decrease in property ppO2 the ascent

greet rc
 
matthewoutram said:
Just catching up with this thread. For along time I've been doing deep stops - I simply understand these stops to be ones that are deeper than the non-GF Buhlmann.

GF based deep-stops just add to the shallow stops, and I've long thought that's where the good feeling comes from. For example 30mins/70m is:

GF15/85 - 120 minute run with a first stop at 45m (last 2 stops: 9m/10mins, 6m/44mins)
GF100/100 - 90 minute run with first stop at 24m (last 2 stops: 9m/8mins, 6m/33mins)

Is this what we mean nowadays by deep-stops or do they mean something else?

I think I'd side with Mark - they GFlo could be moved a fair chunk higher and we'd (probably) still get that feel good factor.

I also agree with Janos - do the crime do the time, it's no hardship (mostly).

Back OT - eCCR for me all the way; why have a dog and bark yourself.

Cheers
Matt.
Click to expand...



I started out using Bhulman bassed IANTD tables and i didnt get bent

The i moved to Deco planner 35/85 and didnt get bent

Then on to a VR3 on zero safety and didnt get bent

And now on Sheerwater GFs on 20/90 and still not getting bent.

(This in on trimix dives mainly 40-80m range for 180min run time in the last 11 years)


Only thing i will say is on OC using IANTD tables i was doing much much shorter dives (avg 20-30min bottom time as apposed to 40-60mins on CCR)

The only relevent things here is the "get shallow quick VR3" with Pyle stops as appossed to the 20/80GF i was running for two years on Decoplanner.



So it seems reguardless of which system i have used i have got away with it dispite being older, unfit and a long time smoker.

But as time has passed i am once more looking at overall in water time and my once comfortable 3 hour personal limit is again being called into question.

I know deep stops are adding to my overall deco, and all the evidance i have managed to gain in the last two years sugests deep stops are at best, not helping and at worst making things worse. So i have to ask my self, why do them any more?

Is running 80/80 actualy better for me than running a much longer 20/90?

I want to give it a go on my next solo dive and see how I feel, but id hate to get bent for the first time so maybe maybe not :D

ATB

Mark
 
Still off topic but I'd definitely recommend reading "deco for divers" by Mark Powell.


I am no expert but I am curious as to which compartments and tissues give rise to a bend and which to the tiredness.

Could it be that you are bending the very fast compartments in first stage of ascent and that this gives the tired feeling which is avoided by Pyle/deep stops?
But during these stops you're still on gassing the slow ones which may give rise to a bend or to longer term health problems?

I dunno, it sort of makes sense that there should be some deeper stops but also that you need to pay for these in terms of longer shallow stops.

anarchista said:
"This is a bad idea, because it is a bad idea."
You said something about studying physics, speak in the language of mathematical analysis.

The CCR need for the device with a higher degree of complexity. Or measurement of galvanic oxygen sensors and electronics, or the measurement of depth and dh/dt (h-depth).
Click to expand...

It may be a bad idea for simply practical terms, it is nice to dil-flush and know it is breathable for one.

For another thing the argument that the O2 cells are a bad thing is a bit weak... on an SCR you'd still want cells to verify it was working. To leave these out would not be beneficial.
 
Dave Sutton said:
Curious what any of this has to do with electronic vs manual ccr's
?


.
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A mod might consider moving everything from post 121 and moving it to a thread called something like re-assessing deco profiles and deep stops, it seems to have taken a nose dive from there, it's still an interesting conversation if you can look past the blatant sanctimoniousness from some ESL protagonists.
 
WFO said:
It may be a bad idea for simply practical terms, it is nice to dil-flush and know it is breathable for one.
Click to expand...
Perhaps you have not read carefully the discussion.
The pure gas technology have solutions, at any depth can rinse closed circut and get an appropriate ppO2, to this particular depth.
You do not have in CCR, with diluent for deep diving.

WFO said:
For another thing the argument that the O2 cells are a bad thing is a bit weak... on an SCR you'd still want cells to verify it was working. To leave these out would not be beneficial.
Click to expand...
If you have a constant ppO2 SCR in its CCR.
When the total death electronics, provides a good platform for the safe completion of decompression. Diluent that does not provide this.

rc greet
 
If you are a scientist using pure gasses sounds like a very good idea, if you are a self sufficient diver it sounds like a very bad idea!! Personally I like to be able to breathe any of the gasses I carry at some point during the dive if I want to.
As far as I am aware you cannot breathe pure gasses unless its oxygen
 
Boys and girls.

We've had another reported post on this thread. I've got better things to be doing on a Sunday than constantly coming back to this thread to see who has said what.

Can I remind you all to be courteous to all members please? I really don't want to have to close it.

Thank you.
 
ccrdave said:
If you are a scientist using pure gasses sounds like a very good idea, if you are a self sufficient diver it sounds like a very bad idea!! Personally I like to be able to breathe any of the gasses I carry at some point during the dive if I want to.
As far as I am aware you cannot breathe pure gasses unless its oxygen
Click to expand...

It is easy to carry out the mixture.

Is the theme of hypoxia, I wrote about breathing nitrogen and under what conditions it was, and that was about it briefly.
The technique pure gases, does not suggest breathe clean inert gas.
The flight can create the appropriate mixture.


greet rc
 
Guys,

We have done the language barrier to death. RC does not have good english, but probably much better than your polish! If you don't understand what he is saying, ask the question in a simpler fashion or ignore it.

RC. In light of the abilities Google Translate, can I please ask you to post your smaller posts in Polish (or type it up and then use GT to get the translation and compare it to what you are trying to say) as this might alleviate some of the language problems. This is an English language speaking forum.

Regards
 
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