But does the model reflect *exactly* what is happening to the divers body, or is it just a close enough approximation?
Measure with a vernier, chop with an axe. Thats diving.
"re-assessing deco profiles and deep stops", plus other bits..
- Thread starter ebt
- Start date
But does the model reflect *exactly* what is happening to the divers body, or is it just a close enough approximation?
Measure with a vernier, chop with an axe. Thats diving.
anarchista
New Member
GLOC
real name: Gareth Lock!
RC,
There are some great models out there for lots of things, but have the models been validated.
The problem with some of the more novel (and maybe accurate) models is that they need a large statistical base to be proven. Until that is the case, then people will obviously be sceptical about them.
Regards
anarchista
New Member
Boot from ppO2 1 on the surface, instead of pure inert gas, ppO2 will not increase, it is the base, which has long been known.
Classic example Buhlmann.
greet rc
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GLOC
real name: Gareth Lock!
Would you not be in a situation where you did a descent to 50m or deeper at 20m/min the ppO2 would be higher than you could metabolise it down? I don't know, I am an OC diver...
Are you saying that Buhlmann is validated or not before I answer...
Regards
Not if you're using dil that doesn't contain oxygen.
Assume you're not metabolising oxygen. You go down, the loop compresses, the ppO2 rises, but then you breathe in, the ADV triggers and adds inerts to restore the volume. After every breathing cycle, the loop volume is the same (V), you didn't add oxygen (so nO2 is the same). pO2=nO2RT/V is the same.
You have the solenoid or CMF or manual add to compensate for metabolisation.
This is generally considered a Bad Idea
I haven't heard or read any evidence of that.
Not only that but,
You're then using as an example, like, the one model (these days) that doesn't want you to do deep stop?
Really?
:boggle:
Cheers,
Matthieu
Assume you're not metabolising oxygen. You go down, the loop compresses, the ppO2 rises, but then you breathe in, the ADV triggers and adds inerts to restore the volume. After every breathing cycle, the loop volume is the same (V), you didn't add oxygen (so nO2 is the same). pO2=nO2RT/V is the same.
You have the solenoid or CMF or manual add to compensate for metabolisation.
This is generally considered a Bad Idea
I haven't heard or read any evidence of that.
Not only that but,
You're then using as an example, like, the one model (these days) that doesn't want you to do deep stop?
Really?
:boggle:
Cheers,
Matthieu
Mark Chase
ATB=AlwaysTalkingBollocks
Hasn't all recent testing found deep stops to be a bad idea? extending shalow deco at best and extending the suceptabuility to getting bent at worst?
Prety much every one is shying away from the very deep stops so fashionable in the 00's. I remember pointing out to a few of my GUE buddies their deep stops were below 0 GF. Still i fell for the hype and ran 10/90.
All the old rhetoric about "get the deep stops right and you can ignore the shallow stops" (GI III) turns out to be just bollocks. Do deep stops and you need to add time to the shalow stops.
Thease days i am running 25/90 and thinking about altering that to 30/90 with the more I here about deep stops being not so good afterall.
I am prety sure Buhlman was the ONLY model that was validated through testing
Theres also the Comex tables (only ones properly tested for helium) but they would massivly increase the deco we normaly do so not many are usng them.
ATB
Mark
anarchista
New Member
Would you not be in a situation where you did a descent to 50m or deeper at 20m/min the ppO2 would be higher than you could metabolise it down? I don't know, I am an OC diver...
Are you saying that Buhlmann is validated or not before I answer...
Write the truth which is not widely known.
The technique pure gases remain constant ppO2 .
The closed loop of a large excess volume of the breathing bag, ppO2 little increase. do not exceed 1.5-1.7 (By the ratio between the total volume of the circuit, divided by the rigid volume of the circuit).
Only in pure gases technique.
The speed of 20m/min compression is too high due to the effect described by Professor Gulyar. the link is in the discussion of hypoxia
For YD gave the settlement discussions in a tension in the tissues, from which it is clear that even the NX 50 increases the saturation in increments that are controlled decompression below the surface.
You see that ppO2 remained stable.This is generally considered a Bad Idea
I know a couple of solutions that eliminate the problem of flushing at any depth.
Why is this a bad idea?
Polish Dr. med J.Kot working in hyperbaric therapy, presented material on deep stops. Advantages appeared at longer exposures. Which is in line with new models for rapid tissue.
That's as much as I can say.
rc greet
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Totally agree, Mark.
Not so recent research, but yes.
And while other models have been pretty well tested (the Navies' ones), Buhlmann may be both the most tested and the only one for which all the data is readily available (that's why it's so popular). Note that this testing did not include diving below 100m or trimix, AFAIK. Also Buhlmann + GFs is not Buhlmann.
At best it's solving a non-problem. At the low low cost of adding real and obvious ones.
Simply because you allegedly have unspecified solutions to those doesn't make it a problem worth solving.
Why not solve real existing problems instead?
I did indeed hear that this may be the case, but this "as much as I can say" stuff is bollocks.
Serious scientific work include publication. So put up a link otherwise it's just blahblah.
Cheers,
Matthieu
Not so recent research, but yes.
And while other models have been pretty well tested (the Navies' ones), Buhlmann may be both the most tested and the only one for which all the data is readily available (that's why it's so popular). Note that this testing did not include diving below 100m or trimix, AFAIK. Also Buhlmann + GFs is not Buhlmann.
At best it's solving a non-problem. At the low low cost of adding real and obvious ones.
Simply because you allegedly have unspecified solutions to those doesn't make it a problem worth solving.
Why not solve real existing problems instead?
I did indeed hear that this may be the case, but this "as much as I can say" stuff is bollocks.
Serious scientific work include publication. So put up a link otherwise it's just blahblah.
Cheers,
Matthieu
anarchista
New Member
You do not present any publications, to support argument.
Do you belong to a scientific society, involved in diving medicine or hyperbaric technique?
The first question Martin Parker on the SCR SMS oxygen chemically acumulated addressed, how ppO2 stabilize the ascent.
A similar question asked in the Aqua Lung Military.
You're not in the league as they are.
rc greet
Mark Chase
ATB=AlwaysTalkingBollocks
Just to clarify my thought process on Bhulamn
If we accept Buhlman as being 100/100 GF and we agree this is for young fit men in the navy, then this is our baseline for deco.
Again if we agree GF is a way of manipulating Bhulman to make it less aggressive for us older un-fit types then the question is why are we adding deep stops?
If we accept Bhulmans model then shouldn't we be running 80/80 rather than 20/80?
In my view we have added the deep stops with the purpose of mimicking VPM bubble model which is untested and has little or no validation outside a calculator.
The original VPM appeared to all about reducing deco and certainly the shallow stop times were impressive (or scary depending on your view point) but over the years it seems to me VPMB has fallen more in line with the final shallow deco times of Bhulman 100GF with a move toward more conservative settings on VPMB by users.
On bigger dives (100m+) we have divers using VPM for the deep stops and mimicking Bhulman for the shallow stops?
On the surface this looks to me like short shallow dives = aggressive deco and you get way with it, but when things get more serious you need to do proper deco.
I haven't had the balls to try it yet but I am starting to think 80/80 isnt such a bad profile.
Bend and mend we are told. But the only proof we have to go on is the crazy antics of Richard Pyle. And that gave us the much maligned VR3 profile.
ATB
Mark
when I dived the inspo I didnt do any stops, I followed the ceiling, as it moved I moved
When I run GF,s 15/85 I get out of the water feeling fine, If I run buleman without gf's I get out the water feeling like shit!!
very unscientific observations and the only time I have been bent is when I missed a deep stop, got a hit in my elbow so went back and did my deep stop (36m) and the pain/bend went away!!!!!!
very unscientific!
When I run GF,s 15/85 I get out of the water feeling fine, If I run buleman without gf's I get out the water feeling like shit!!
very unscientific observations and the only time I have been bent is when I missed a deep stop, got a hit in my elbow so went back and did my deep stop (36m) and the pain/bend went away!!!!!!
very unscientific!
I have been doing same and nicknamed this approach / theory Sudoku deco. Start out with something aggressive on your computer then fill in numbers on your stops based on the variables of watching the celling, your PPO2 drop rate while manually maintaining set point and the quality of the tunes on your ipod. If I come out fast it's fatigue, if I come out slow it's bouncy happy and no need for a nap, the exact GF will change based on those items and my state going into the dive aka fresh, tired, cold, dehydrated or other but I want to know a baseline to work from where I can then make my own decisions.
As an anecdote, due to some cell issues last year (they were over-reporting PPO2 by .2) for about 5 x 60M / 2H dives I was VERY sleepy after them and in hindsight realised I had defo been skipping deco, not an experiment to be repeated but for me at least I know less deco = fatigue.
anarchista
New Member
Janos
"Two sheds"
I thought Bulhman thought 100/100 was too aggressive and backed it off a bit?
-----
Personally:
1) I set a GF-low of 35, but I struggle to meet the ascent rates required. In practice I end up ascending slower than this and so a lower GF.
2) With a heated vest, and an underwater MP3 player, the downsides of doing too much deco are small. I saw a practical study over on the other place that showed that a GF of 75 lead to a lot less bubbling than 80. So much so that many of the participants of the trial moved to a GF-high of 75.
So I tend to programme the Shearwater to 30/80, but accept that I stop deeper than this, and I overstay the 6m stop for a bit of extra conservatism...
Janos
Janos
"Two sheds"
On the ECCR / MCCR debate, I dive a hybrid. It forces me to monitor my ppO2 religiously [1] but if I cock up then the solenoid fires and I swear at myself for not being as vigiliant as I should be.
Perhaps Bruce can invent a wirelessly controlled gizmo that applies an electric shock to a sensitive part of the divers body if ppO2 goes outside a certain tolerance. That would make my ppO2 control even better!
Janos
[1] - Ie with incense, chanting, and a few prayers.
Perhaps Bruce can invent a wirelessly controlled gizmo that applies an electric shock to a sensitive part of the divers body if ppO2 goes outside a certain tolerance. That would make my ppO2 control even better!
Janos
[1] - Ie with incense, chanting, and a few prayers.
GLOC
real name: Gareth Lock!
RC, I am a member of both UHMS and SPUMS. Can you send me the links?
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
Mark Chase
ATB=AlwaysTalkingBollocks
Totaly agree on tthe 100/100 being agressive but I am wondering if we should be running 75/75 tather than 30/75?
Why are we doing the 30?
What is a deep stop?
Doing a big profile like 80m for 40mins and running 30/75 we get 215 mins ascent time and a first stop at 45m
Running it 75/75 we get a first stop at 36m
So only 9m diferance? but we save 20mins deco for the same GF high?
So why are we bothering with the stop at 45m?
Isn't 36m still a deep stop?
I dont know the answer, but It does make me think I may be doing it wrong and for the all wrong reasions.
ATB
Mark
anarchista
New Member
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