Slow tissue on gas from stops

[Patoux01]

I've shown that I don't depend on a certain deep stop level, and besides, UTD doesn't even require the use of Ratio Deco in technical classes, so what's your point?

I have a question. If UTD doesn't seem to give a damn about making people use RD, why did it spend so much on showing the world RD is best (and failed) ?

 

[Dan_P]

Because to me, your arguments remind me quite a bit of the tactics so brilliantly described in Conway's and Oreskes' "Merchants of Doubt"

If that's a hidden agenda, it's in pretty plain sight.

I have a question. If UTD doesn't seem to give a damn about making people use RD, why did it spend so much on showing the world RD is best (and failed) ?

I don't think it's about whether or not UTD gives a damn, to be fair. I don't know what to tell you;

I'm just saying an instructor with UTD is not obligated to use RD on technical dives, and it's possible for a student to take a UTD-class and not use RD.
So deep stops aren't synonymous with UTD and I don't have an economic dependency on maintaining any certain deep stop emphasis.
I think a lot of people have gotten that bit wrong...

But, that's all UTD and RD.
I feel this discussion is a bit broader than that.

 

[Storker]

If that's a hidden agenda, it's in pretty plain sight.

[...]

I don't have an economic dependency on maintaining any certain deep stop emphasis.

I told you what your style of arguments reminded me of, I never accused you for having a hidden agenda.

And I can't remember anyone - except you - bringing up accusations of you having an economic interest in deep stops or ratio deco.

Again:

 

[RayfromTX]

Dan
With all due respect sir, you are perhaps too close to this discussion. As an outside observer, it seems obvious to me that the only thing you are convincing anyone of is that you are determined to have the last word and that while you seem to have retreated on the major points to a place where we are wondering what you are still arguing about, you remain willing to find something to argue about. It has come to a place where it is like that bad movie that I've spent 90 minutes watching, convinced it was just about to take a twist that makes that investment of time worthwhile but in the end I realize that there was no more there there.

On the upside it is great to see that this topic can be discussed with civility. When RH was banned from the thread, that ended the name calling and accusations. That is a very good thing because all of the participants are well educated, intelligent and worthy of our respect. I suspect that anyone here could teach me and each other much. Thanks for keeping the discussion out of the pit. Now, there is another even higher place that we could take discussions like this where we only speak with respect to each other and only when we have something additional to add but I rarely see that happen online unless the participants are all acquainted in real life. Those discussions build into a sum that is greater than the participating points of view. Here's hoping we get there.

 

[PfcAJ]

Which solution do you use that sorts it out?

I plan my dives without the deep stops? That’s fairly obvious.

The first example is the most obvious to me. You can plug in a pair of gradient factors that don’t stop you as deep as say vpm2, and still use 50% as a deco gas.

Even for ratio deco rule of thumb type ascents, it’s super easy to modify the plan to eliminate time spent before the gas switch. Maybe on a 240’ Dive for 25mins, instead of 30fpm to 75% avg depth, then 10fpm from there till 50% avg depth, then 5fpm from 50% to the 1st switch, change it to 30fpm to 50% and then 10fpm to the 1st switch. Whatever mirrors non deep stop gradient factors. I’m not even looking at deco software but it’s clear the approach #2 skips time spent dilly dallying before you get on a deco gas and is still easy to remember.

It’s not even difficult.

 

[boulderjohn]

I'm just saying an instructor with UTD is not obligated to use RD on technical dives, and it's possible for a student to take a UTD-class and not use RD.
So deep stops aren't synonymous with UTD and I don't have an economic dependency on maintaining any certain deep stop emphasis.
I think a lot of people have gotten that bit wrong...

When did this change?

When I took my tech diving classes through UTD, I was absolutely required to use Ratio Deco. A key part of my training was why ALL other algorithms were wrong and ONLY Ratio Deco provided a "proper" ascent profile. Those others were demonstrated to be wrong solely on the basis of the fact that their profiles were different from the UTD Ratio Deco profiles, which were assumed to be perfect.

 

[Dan_P]

When did this change?

When I took my tech diving classes through UTD, I was absolutely required to use Ratio Deco. A key part of my training was why ALL other algorithms were wrong and ONLY Ratio Deco provided a "proper" ascent profile. Those others were demonstrated to be wrong solely on the basis of the fact that their profiles were different from the UTD Ratio Deco profiles, which were assumed to be perfect.

I'm sorry, but while I have respect for you and follow with great curiosity and pleasure most of your posts, as so very often when you talk about RD, I can't relate. Probably that's because I simply cannot recognize the methodology, attitude, content or relation to Standards and Procedures in what you're describing.
Granted, things may have changed, so I'm not saying you're wrong.
But if the assumption is that the above is representative of today, I can confidently say that's an incorrect assumption.
But, to answer your question; if there was a change, I don't know when it was.

I plan my dives without the deep stops? That’s fairly obvious.

The first example is the most obvious to me. You can plug in a pair of gradient factors that don’t stop you as deep as say vpm2, and still use 50% as a deco gas.

Even for ratio deco rule of thumb type ascents, it’s super easy to modify the plan to eliminate time spent before the gas switch. Maybe on a 240’ Dive for 25mins, instead of 30fpm to 75% avg depth, then 10fpm from there till 50% avg depth, then 5fpm from 50% to the 1st switch, change it to 30fpm to 50% and then 10fpm to the 1st switch. Whatever mirrors non deep stop gradient factors. I’m not even looking at deco software but it’s clear the approach #2 skips time spent dilly dallying before you get on a deco gas and is still easy to remember.

It’s not even difficult.

Fair enough. I don't have a problem with how you dive.
I'm saying all the examples I brought up, are super easy for me to utilize in the same solution across all dives and I appreciate the use of RD for those things, among others. That's all.
I'm not saying or implying that I know RD to be superior to "your way", or trying to take a dig at you with that.

Dan
With all due respect sir, you are perhaps too close to this discussion. As an outside observer, it seems obvious to me that the only thing you are convincing anyone of is that you are determined to have the last word and that while you seem to have retreated on the major points to a place where we are wondering what you are still arguing about, you remain willing to find something to argue about. It has come to a place where it is like that bad movie that I've spent 90 minutes watching, convinced it was just about to take a twist that makes that investment of time worthwhile but in the end I realize that there was no more there there.

On the upside it is great to see that this topic can be discussed with civility. When RH was banned from the thread, that ended the name calling and accusations. That is a very good thing because all of the participants are well educated, intelligent and worthy of our respect. I suspect that anyone here could teach me and each other much. Thanks for keeping the discussion out of the pit. Now, there is another even higher place that we could take discussions like this where we only speak with respect to each other and only when we have something additional to add but I rarely see that happen online unless the participants are all acquainted in real life. Those discussions build into a sum that is greater than the participating points of view. Here's hoping we get there.

Hi Ray,

I'll leave it with this, then - I still feel there are open questions (even prompted within highly relevant reports) which are dismissed when asked or highlighted in these discussions.
I still feel that there are natural concerns about specifics within the studies we have available, which are dismissed in the debate.
I still feel that disproportionate perceptions of the concepts we're discussing, appear to me as common, online and -off.
I still feel that because I ask such questions or highlight such concerns, the perception is that it must be because I have some agenda. Even when showing how I do not have an agenda, somehow that's all of the sudden an argument (see strawman depiction above).

All of that aside, what I'm saying is: what I see is that deep stops have not been shown to be unsafe. "Probably suboptimal when overemphasised", sure. I don't have a problem with that - but that's different. And I think it's important to stress the difference.

I understand that you're saying about proximity, and in fairness to you, there is something to that. Of course, I don't think that makes what I'm saying any less valid, and I'd like to reiterate that I don't have an interest in maintaining any specific deep stop level per sé.

 

[dmaziuk]

The discussion is very interesting but going way over my head. I just do as my computer tells me and don't question it, however if would be interesting to learn a bit of the science. Are there any online resources that explain all this starting from the very basics?

There are Eric Baker's articles, VPM & GF for dummies on rebreatherworld, and various other bits and pieces like computer code, but I can't think of anything online that starts with basics and has it all in one place.

 

[tursiops]

I'm saying all the examples I brought up, are super easy for me to utilize in the same solution across all dives and I appreciate the use of RD for those things, among others. That's all.

So, first you say that your use of deep stops is for logistical convenience. I ask what you mean by logistics. You provide four examples, none of which require deep stops, but rather argue for RD. You are being inconsistent, and arguing for the sake of arguing. That is tiresome to the point of being irritating. I can only assume you are a sock puppet for Ross, except more articulate.

 

[UWSojourner]

Actually, it's a lot of charts to show how fact and figure can easily be misrepresentative of truth.

The new argument is "deep stops are not unsafe." Of course the double negative implies you're trying to support, with all the research out there, that "deep stops are safe."

Clearly that is not what the research is showing us. The clear message of the research out there is that the bubble-model-style, RD-style, deep stops reduce safety in a profile.

As deco obligations mount (i.e. real tech diving), the difference in profiles (i.e. deep stops causing more on-gassing in slower compartments) steadily increases. It's this difference that the NEDU concluded caused the increase in DCS in their study.

Throughout this "debate", many arguments have been tried:

• The study was flawed -- as people learned how carefully conducted the study was it just didn't gain traction.
• The profiles were too odd to have crossover value to tech diving -- but it was shown how close the failing profile was to VPM-B so this argument didn't take hold (for most).
• Bubbles in divers don't matter -- this was simply bizarre, but it was argued that all the bubbling being observed in those following deep stop protocols really didn't matter.
• It's all a research conspiracy of academics with an agenda -- not much to say about that one, but the public doesn't have a really high percentage of conspiracy nuts.
• Standard measures of decompression stress (i.e. time exposed to supersaturation) are invalid -- since almost all models (including VPM) use these measures that one didn't fly either.

And now we have (from a dive instructor) an admission that deep stops are less safe, but "not unsafe". I doubt many tech divers will be planning dives thinking, "I could have a safer profile, but I'd rather have one that's not unsafe." Doublespeak at best.