Son of Deep Stops *or* Waiting to be merged with the mother thread...

[dmaziuk]

so...were're back where we were with enough less name-calling to remain open

Just give it time

 

[David Doolette]

ummm... "work on the bottom and cold during decompression"??? The during deco part was a misspoke thing right?

It seems to me that cold sans work would be a much worse case than cold with work regarding deco needs... just postulating.

Of course work followed by cold not working during deco would be really bad.

Yes, those last were the conditions of NEDU TR 11-06. I must need some additional punctuation in my earlier post.

David

 

[lowviz]

so...we're back where we were with enough less name-calling to remain open

If you mean nobody's mind was changed by the arguments, you are correct. However, several insights have been given/slipped out along the way and that is the real value of continuing. (for me)

It would be most helpful if the experts could assign a single numeric value to a particular profile which directly relates to deco burden or as the French say, "exposure". Total deco time seems to be an imperfect predictor. UWSojourner pointed out to me that total deco time is, in effect, very similar to my "exposure" estimate.

Using the old tables, 70 feet for 70 minutes is the same as 120 feet for 30 minutes. Both require 14 minutes of deco. Bubble theory seems like it should say no, they are different, the 120 dive is bigger. I have to start poking around in the new dataset that Dr. Doolette offered. All suggestions/criticisms welcome...

 

[Ayisha]

The stops are all shallow - and one had its stops offset further by an average of 10 ft - all still shallow. No deeps stops anywhere to be found or seen.

And yet a statistically significant number of participants got bent with these "shallow stops". So it is obvious that beginning the stops deeper while not increasing the overall decompression time or time spent shallower would have exacerbated the decompression sickness. Throwing in your deep stops with the same run time would have likely been "disastrous", as you like to say.

If that were not the case and you were fully confident in your VPM-B program, you would not be working on your new improved model, VPM-C. Miraculously, this VPM-C program will likely be somewhere in between bubble models and diffused gas models, and will graph like the most popular GF representations...

 

[rjack321]

Using the old tables, 70 feet for 70 minutes is the same as 120 feet for 30 minutes. Both require 14 minutes of deco. Bubble theory seems like it should say no, they are different, the 120 dive is bigger. I have to start poking around in the new dataset that Dr. Doolette offered. All suggestions/criticisms welcome...

All factors inclusive, deeper is riskier. There's a definite "knee" in the survivorship curve past about 220-240ft

Finding measurable differences between 70 and 120 and 14 and 14 is going to be next to impossible as those types of small differences are going to get lost in the inherent individual variation. Some people could get away with no deco at all for those

 

[dmaziuk]

Hmm... so you're looking at roughly half the time at double the pressure. One wonders how on-gassing depends on the pressure differential in different models...

EDIT: sorry, brane fart. Not double the pressure.

 

[Dr Simon Mitchell]

No, not cherry picking. You said VGE were not correlated with DCS.

Simon and I have acknowledged, dozens of times on these threads, that "The detection of bubbles in any individual is not diagnostic for decompression sickness (DCS)." The truly bizarre part of this argument is that you are quoting something I actually wrote.

Our point, and the one that makes you uncomfortable, is that if a schedule is dived multiple times, and the median peak VGE grade is, say, 3 or greater, the correlation of VGE and DCS suggests the schedule has a relative high risk of DCS compared to a schedule that results in lower VGR grades.

Simon and I have acknowledged, dozens of times on these threads, that "The detection of bubbles in any individual is not diagnostic for decompression sickness (DCS)....

 

[rjack321]

Hmm... so you're looking at roughly half the time at double the pressure. One wonders how on-gassing depends on the pressure differential in different models...

EDIT: sorry, brane fart. Not double the pressure.

3.1 vs 4.6 ata
So you're holding deco time constant
But going about 48% more atas deeper
And get less than half the bottom time
If depth were all equally stressful you'd only have 48% less bottom time when you actually have 42% less BT.

In other words, you're illustrating how even within recreational depths still 50ft deeper is 6% more stressful from a gas loading perspective. A bigger depth difference would magnify this divergence.

 

[Dr Simon Mitchell]

VGE are associated with profile stress only, but not correlated

I don't think you understand this matter.

You are fond of citing the VGE consensus document.

Go and read it. As David (who is an author on it) has categorically told you, it clearly states that VGE grades are correlated to risk of DCS.

Simon M

 

[rossh]

And yet a statistically significant number of participants got bent with these "shallow stops". So it is obvious that beginning the stops deeper while not increasing the overall decompression time or time spent shallower would have exacerbated the decompression sickness. Throwing in your deep stops with the same run time would have likely been "disastrous", as you like to say.

If that were not the case and you were fully confident in your VPM-B program, you would not be working on your new improved model, VPM-C. Miraculously, this VPM-C program will likely be somewhere in between bubble models and diffused gas models, and will graph like the most popular GF representations...

No .... deep ..... stops..... Extended shallow were all that got used in the nedu test. First stop in the nedu test.is12 minutes at 70ft ??

Obviously trying to invent some relation between a 12 minute stop at 70ft, vs a 1 min stop at 110 ft, is just plain fictitious.


Why new models? Because the current ZHL side is worn out. the GF method is abused to excess, and needs fixing.



Commercial footnote: We make a program called MultiDeco. It has most of the current deco models and variations available for you to choose from. Your welcome to choose any model, and to do as much, or as little deco time as you want - its your choice.