Helium penalty

[rossh]

Not from that diagram they can't. All you have indicated in your diagram is the approximate first stop depth for different GF Lo values. The true measure of "deep stoppiness" of a decompression profile is depth and time, because Ross, tissue gas uptake (especially in slower tissues) takes time.

Using Table 1 from the NEDU study and your own program, decompression stop time at 18m or deeper for the NEDU test profile (52 m for 30 min on air):

NEDU deep stops profile = 29 min
ZHL16-C GF 60/77 = 3.5 min

You will have to explain to me the basis of your belief that 29 vs 3.5 minutes are somehow an equivalent amount of deep stopping in which tissue gas uptake by slower tissues would be the same or similar.

Simon M

Simon. You just conceded to the reality that the Nedu study A2 profile is NOT a "deep stop", but is in fact a multi-level ascent plan. That's a point I have made a thousand times, and you kept denying.

When the first stops equal or exceed the actual bottom time, then its a multi-level dive.

No deco program or model will make or suggest a 29 min deep stop. Deep stops are a few minutes only. The Nedu program used a profile that tried to emulate something by magnifying it ten (10) times normal. This is clearly beyond "sensible bounds", and highlights the absurd and unrealistic levels the Nedu test used to create a biased outcome.

This confirms another point, that the Nedu A2 profile is a hand made creation, and NOT a product of some imaginary bubble model. We knew this already because the project designer (Gerth) was on video some 16 years ago, giving a pre-test briefing describing how and why the ascent deliberately inserted this unnatural feature.

Thank you for finally realizing the Nedu test is not representative of tech profiles or deep stops. You can argue about extra on gassing in the nedu test, but the amount in the test is not realistic or relevant to real diving conditions.

A diagram to show this...

[Mal]

it looks like Christmas is upon on us ... assuming this thread will follow the path of many others of a similar vein, please can I remind all posters that you should “play the ball and not the man”

thanks
Mal

[cathal]

To save us all again from this never ending circular argument,give us one peer reviewed paper that supports and or validates your theory Ross. As thats what Simon has done.

[Chimp]

I just can’t see what the argument is about anyway? Why has it become so personal? So far as I can tell (and I’ve followed a fair bit of this ‘debate’ over the last while here and in other places), the good doctor is simply saying that the limited amount of evidence we have (based on real testing on real divers by real scientists in real controlled conditions) suggests we might be having less efficient deco by making a first stop too deep. Why has one person taken such a vehement exception to this? Simon reiterates time and time again that he is not saying we should abandon bubble models completely at this stage or even that we should not continue with deep stops, but simply brings to our attention, in an accessible way for the ‘ordinary’ diver, the evidence available thereby allowing us to make our own mind up on what is after all still a game of chance/statistics (the first thing I was ever told when I started diving; “if you want 100% safety don’t get in the water”). Decompression theory is just that; theory. It’s not yet an exact science that can be reduced to algorithms and mathematics (and probably never will be given that we are all unique).

My own opinion (not that it matters of course) is that I’ll take hard evidence from human trials over theory based on gel models any day. That’s why I currently run 50/75. I am open-minded though and happy to follow any new evidence in future as and when.

[rossh]

To save us all again from this never ending circular argument,give us one peer reviewed paper that supports and or validates your theory Ross. As that's what Simon has done.

You asked, so here it is.

It is not a "my science vs your science" argument. Problem is, and continues to be Simon's interpretations of the papers and his opinion of them that he pushes onto us. Yes, the "ball" here is one mans opinion.

As can be seen in just one example of the previous post above, he (and those who precisely follows his opinion), are working from a false premise, and that fallacy position is easily shown up. Simon's false interpretations of the papers are the issue, and which he uses to create a false narrative and promote invalid understandings directed at divers. The nedu test is the central deception in all this.

He goes to great effort to disseminate these falsehoods, on youtube, and through public conferences, and getting into agency training, and using junk science measures and marketing graphs. He does all this to push his personal desire to change deco into what he wants.

Now, If you lot want to go on a search of the holy grail of deco, then go right ahead - fine by me. But please stop lying to yourselves with phony justifications. Please stop lying about the success of the deeper stop models and methods. Please stop distorting deco theory to fit that phony narrative.

[cathal]

You asked, so here it is.

It is not a "my science vs your science" argument. Problem is, and continues to be Simon's interpretations of the papers and his opinion of them that he pushes onto us. Yes, the "ball" here is one mans opinion.

Ross , this is not what what I suggested in my post above. I asked for you to have your theory peer reviewed and published so that we can take comfort from the fact that subject matter experts have independently validated your hypothesis to date, which I note has yet to happen.

Now, If you lot want to go on a search of the holy grail of deco, then go right ahead - fine by me

Its in our own interest to do so Ross

But please stop lying to yourselves with phony justifications. Please stop lying about the success of the deeper stop models and methods. Please stop distorting deco theory to fit that phony narrative.

Ross just get your theory peer reviewed and published so that we can take comfort from the fact that subject matter experts have independently validated your hypothesis to date

[jturner]

It is not a "my science vs your science" argument. Problem is, and continues to be Simon's interpretations of the papers and his opinion of them that he pushes onto us. Yes, the "ball" here is one mans opinion.

I do find it very strange that the original authors of the studies don't seem to have any problem with his "interpretations of the papers and his opinion of them", often agreeing with his summaries. And yet here we have you, claiming it's all a distortion. I'm afraid I'm with cathal on this - compose an paper that examines his analysis and indicates the errors and demonstrate how the studies should have been interpreted and get it published so we can see that it isn't just your internet opinion based on your own belief, but rather, a more correct and accurate understanding of decompression theory and physiology.

[simon mitchell]

Simon. You just conceded to the reality that the Nedu study A2 profile is NOT a "deep stop", but is in fact a multi-level ascent plan. That's a point I have made a thousand times, and you kept denying

Ross, the NEDU profile has been published and in the public domain for more than 10 years. There is no revelation here. The authors have explained the rationale to you many times, but you, of course, are free to call it what you like.

In equating the NEDU deep stops profile with GF60/77 you have demonstrated that you don't understand gradient factors; which (among many other things) stands alongside your previous insistence that tissue blood flow is not a critical determinant of gas uptake and elimination as a warning to everyone that your knowledge of this field is extremely limited.

I do find it very strange that the original authors of the studies don't seem to have any problem with his "interpretations of the papers and his opinion of them", often agreeing with his summaries. And yet here we have you, claiming it's all a distortion.

Quite (and thank you). The truth is that Ross's claims about me are essentially 100% projection. How on earth would I survive among my peers and as editor of the discipline's top ranked scientific journal if even a tiny proportion of his claims about lies and distortions about a subject of such central importance to the field were true? My only agenda is accurate portrayal of the science to the technical diving community of which I am a part.

Simon M

[Tewdric]

Ross - I’m not sure these arguments are doing you that much good. You’ve achieved a massive amount in diving as far as I can see, but this is a blind alley. You OK?

[shapeshifter]

Simon,

I'm curious about your statement above, "This is why whole body washout of nitrogen is slower than helium".

I can only imagine that this would be measured by monitoring expired gas composition in the hours following a dive but I haven't been able to find anything in the literature.

Do you have any references I could look up?

Thanks
David