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

[victorzamora]

That's why VPM-B stops at +5 ,and even that has gotten to the end of useful range.

No, that's why YOU stopped VPM-B at +5. There's nothing fundamentally different about +7 except you not liking it.

 

[rossh]

Here's what I don't understand, Ross: VPM-B is based off of zero man-testing, has provably flawed theories it's based on, and causes a marked increase in VGE counts. You've said before that as dives get bigger, you have to add conservatism with VPM. You keep calling GF "over-inflated"....but I think that's some pipe-dream to think so. Some GF settings will produce longer deco times than some VPM-B conservatism settings. Many of the recommended GFs cause longer deco times than similarly recommended VPM ascents. Calling it "over-inflated" just because the deco it produces is longer is astonishing to me. You're arbitrarily calling one good and one "grossly over-inflated" without any data supporting you.

And then you call VPM-B "the most accurate...planning model we have." I honestly can't see how to agree with you. You have an abundance of evidence against that. There's an abundance of evidence that the fundamental principles are flawed.

almost every sentence I read here is wrong.......


There are no flaws in its VPM theory. ... Its based on first principles of science, its peer reviewed and published in Bennett Elliot, which is the bible of deco theory.


VGE is not indicated of DCS... this is the current peer position here: http://www.dhmjournal.com/files/Mollerlokken_ConsDevelopmentConference.pdf

Also ALL models make VGE, so trying to isolate VPM-B is a ridiculous nonsense.


The math in the way current GF is implemented causes it to have exponential growth errors beyond what trying to be achieved - go take a look at the source codes. Simple facts and truths.


"....here's nothing fundamentally different about +7 except you not liking it"


By that reasoning, you would claim +1000 was still valid. Except its not... +7 is not valid either. Its more than double that actual base model time.... and therefore no longer has context. That's why +7 does not exist,and anyone who claims otherwise, is just making stuff up.


.

 

[rossh]

It seems you're having trouble implementing gradient factors. Just use the flowchart below and you shouldn't experience the problems troubling you.

Its not coded that way.... it doesn't work that way..... go look at the code.

 

[cerich]

The problem we are discussing is how GF is patched onto the end of a ZHL, and in the current method, it becomes an exponential growth error, that obviously looses contact with what its supposed to represent.


In VPM-B anything past +5 is equally garbage. That's why VPM-B stops at +5 ,and even that has gotten to the end of useful range.

There is no such thing a VPM-B +7. You cannot buy a +7, you cannot make a +7, there is no planning program that allows us to view a +7. It does not exist. And yet by magic, it turns up in someones pretty colored, devoid of dimension, biased to shallow side, comparison chart. I wonder why they cooked up a non-existent data point to compare?

let's not go down that alley on the why again OK?

So to sum it up, we have a situation where possibly both widely used algorithms (GF and VPM) are tapped out as far as the useful range? Where, in your view, does the diver become the test pilot today? 20 years ago that was easy, exceed recreational limits... today there is a much more robust and deep data base.

 

[rossh]

let's not go down that alley on the why again OK?

So to sum it up, we have a situation where possibly both widely used algorithms (GF and VPM) are tapped out as far as the useful range? Where, in your view, does the diver become the test pilot today? 20 years ago that was easy, exceed recreational limits... today there is a much more robust and deep data base.

Here is a little history....

From 2003 onwards, the gold standard was VPM-B and it was used widely. Most in GF land tried to copy it and did dives just like it. In DIR land, they pretty much did the same thing. We have a very successful decade of dives on this approach, and records show this. More than half the world followed this approach in some format. VPM-B has been to great depths and used as is in many different dives successfully.


Things for fine, for a decade.



Then the DIR crowd got a little too confident, and started doing some things that were not right.





Then one day, a man came along and told us its all broken, but he said he knows how to fix it. Except he didn't ..... just made a big mess of things instead.

.

.

 

[lowviz]

The very essence of scientific progress is to perturb the system and observe the result.

 

[UWSojourner]

We all know you have fallen in love with GF Kevin.

Not love. Respect. I'm trying to respect the data as Dr. Pollock encouraged us to do. I'd prefer better data and a model that better reflects it. But GF is a pretty darn good tool and better reflects the current state of research than bubble models do.

If you want to keep using it ... and expect it to be taken seriously, then its time to fix the mistakes {yada, yada}..."

No need to. From this poll over at the Cave Divers, it seems it's already being taken very seriously. 86% use GF. Now, who's claims aren't being taken seriously? --- hmmmm.

 

[UWSojourner]

Except its not... +7 is more than double that actual base model time.... and therefore no longer has context. That's why +7 does not exist,and anyone who claims otherwise, is just making stuff up.

See VPM-B+7 compared to VPM-BE+5 (your method in your software). I doubt divers are going to buy your "+7 is fake" shtick.

 

[rossh]

VPM-B/E exists since 2004 and has been dived many times.


However, +7 does not exist anywhere...... it was cooked up. +7 was "invented" by Kevin so he could be "fitted" into an equally invalid set of graphs, that are deliberately biased to the shallow side.


Not quite the same thing. Real plans vs .....

 

[Storker]

when my operational range is covered by either model equally well, I'll take the simpler one.

From a purely practical POV, that's just fine. As long as the model fits experimental data both on the low and the high side of where you are, it doesn't matter (from a practical POV, that is) whether the model you choose has anything to do with reality.

To get back to my example: If you only want to know when the sun rises tomorrow, it doesn't matter whether your model thinks that the sun orbits the earth or the earth orbits the sun. You might run into problems if you want to know what happens a hundred years from now, or what happens on Mars, but if your only concern is when the sun rises tomorrow, you're good no matter which model you use.