Manual calculation for accelerated deco

[lowviz]

I think that he does count. Riding Blind with your DSMB reel

I see three clear divisions. Those who are coming up with entirely new ideas based on testing and observation, those who are modeling 'accepted' deco theory in various ways, and those who just dive the results of either of the first two scenarios on faith.

 

[Dan_P]

That's why I went to Jarrod Jablonski for that information--or doesn't he count?

My point is I don't have trot with a notion that "there is no science behind it".
I'd be hard pressed to believe a Jarrod Joblonski would come out with such a statement, especially because that would inherently imply that the algorithms it resembles, have no science behind them either.

Further, RD doesn't just "approximate what DecoPlanner would do".
Beside the fact that RD outdates DecoPlanner, it takes into the equation a great deal more practical aspects of diving than does any other solution hence or presently in existence.
Simply portraying it as a crude approximation of an algorithm, using certain gases, is a rather unprecise formulation that underplayes key aspects of it's application.

As is presenting a view that it's a set-in-stone prescription for ascending.

That's my point.

For an answer to what the difference between GUE RD and UTD RD is, I wouldn't even bother.
UTD chose to keep using and updating it. GUE didn't. The end.

 

[boulderjohn]

Further, RD doesn't just "approximate what DecoPlanner would do".

I depends upon which version you are using.

In our conversation, Jarrod (GUE) stressed that RD does indeed replicate what a software program like DecoPlanner would do. In fact, he said students creating a RD plan in class must check it against a DecoPlanner schedule.

In total contrast, when I took my Ratio Deco class from Andrew Georgitsis and learned the UTD version of RD, another UTD instructor in the class ran each of the RD profiles we created through a variety of established decompression software programs, and they never matched. That fact was celebrated. Andrew said that UTD's Ratio Deco created a "proper" ascent profile, and the fact that those profiles did not match anything created by established decompression software demonstrated that those programs were all wrong.

So what was the science behind that?

Well, I first tried to take the Ratio Deco class from Andrew via a webinar, but we only did the first part. I had to wait until much later to take it from him in person. During the webinar, a woman asked him for the science behind it. He said, "You have to have faith." "Faith in you?" she asked. "Yes," he answered.

Since my UTD group was doing all of its diving at altitude, I was concerned about the fact that we were making no adjustments to the standard RD formula for our diving. Andrew insisted that there was no need to adjust RD for high altitude diving. I asked him for the basis of that claim, since all other algorithms do adjust for altitude. He told me that he dives at Lake Tahoe without adjusting Ratio Deco, so that proved that no adjustments are necessary. (That conversation was the actual reason I talked with Jarrod to get the GUE perspective. His perspective, by the way, was that since Ratio Deco had been developed in accordance with DecoPlanner at sea level, it could not be used at altitude without adjustment. Since they did not dive at altitude, they did not have any means of adjusting it.)

 

[PfcAJ]

My point is I don't have trot with a notion that "there is no science behind it".
I'd be hard pressed to believe a Jarrod Joblonski would come out with such a statement, especially because that would inherently imply that the algorithms it resembles, have no science behind them either.

Further, RD doesn't just "approximate what DecoPlanner would do".
Beside the fact that RD outdates DecoPlanner, it takes into the equation a great deal more practical aspects of diving than does any other solution hence or presently in existence.
Simply portraying it as a crude approximation of an algorithm, using certain gases, is a rather unprecise formulation that underplayes key aspects of it's application.

As is presenting a view that it's a set-in-stone prescription for ascending.

That's my point.

For an answer to what the difference between GUE RD and UTD RD is, I wouldn't even bother.
UTD chose to keep using and updating it. GUE didn't. The end.

It doesn’t outdate the buhlmann algorithm.

And the entire point of RD is to mimic the output of an algorithm. Otherwise you’d have no baseline to compare it to (which seems to be increasingly what UTD is attempting).

 

[victorzamora]

UTD chose to keep using and updating it. GUE didn't. The end.

This might be the funniest thing I've ever read on Scubaboard.

 

[Dan_P]

In our conversation, Jarrod (GUE) stressed that RD does indeed replicate what a software program like DecoPlanner would do.

This was after the guy who made RD left that outfit, yes?
Shocking.

Again, DecoPlanner was made after Ratio Deco. The chronology doesn't fit your anecdote.

Now, I'm not going to pretend I was present in the situations you mention - my point is that there are other aspects to ascending than just decompression, and that simple fact is left out of too many conversations, considerations and indeed this very string. In spite of the fact that they're extremely important (at least, I think they are).

If you can't run a given ascend while maintaining an average of some specific ppO2, say of 1,2, one might in some perspective reasonably fairly argue it's not really a "proper" ascend strategy at all, wouldn't you say?
1) you can't dive it on a rebreather, and 2) if you could, you wouldn't be able to run it anymore if you bail out from that rebreather, and 3) you can't run it as a team if one member is on open cirquit and the other is on closed cirquit.

Is that what someone was referring to in a given situation ages ago? Maybe some student wasn't getting the whole picture, and the instructor, tongue-in-cheek, just said "trust me". Who knows.
I know that's no argument for or against, but by the very same mechanism, neither then is the initial narrative about "faith".

In fairness, I could turn any and all of these arguments around and ask you how you know whichever algorithm you subscribe to, is "optimal"?

How you figure out if your computer has accounted for external factors reasonably, how you ascertain that none of the divers you train ever "follow" the computer blindly?
That your gear, diver training/capacity and knowledge, depth, gas availability, bottom time and ascend framework all add up?

And then there's the ease of planning, pre-splash, and carrying out adjustments in-water.

To say RD is simply a crude attempt to repliate or approximate some algorithm, seems either ignorant or intransparent.

As for the altitude thing - if you know or believe altitude is a factor, account for it. If you believe or know cold is, you account. If you feel dehydrated or exhausted, you account. Not your computer, but you.
So your computer isn't functioning right because it can't adjust for the temperature impact, if any? That's the extention of the logic you're presenting.

Further yet, consider the implications of what you're saying.
At 2.000m, you're looking at ca. 0,8 bar.
That means the delta relative pressure difference on ascending from 3m to 2m across sea level (1,3 bar at 3m) and 2.000m altitide (1,1 bar at 3m), is less than 1,5%.
The impact of that on an ascend is about as significant as a burp.
If that little difference is what's winding you up in terms of decompression, you'd never do a repetitive dive, ever. Or dive in cold water, for that matter.
Besides, you're talking about, say, making a pressure drop from 6,0 bar to 1,0 bar versus making a pressure drop from 5,8 bar to 0,8 bar. The total difference is still 5,0 bar. Saying there's a difference in those two dives in terms of bubble propagation equals actively advocating the significance of Boyle's Law on micronuclei (read: deep stops).

It's a matter of fixation, that whole anti-RD buzz.

 

[lowviz]

...//... As for the altitude thing - if you know or believe altitude is a factor, account for it. ...

Are you freaking serious? THAT is physics, pure and simple.

If not accounting for another baseline atmospheric pressure is not something of the least question to you, then you best return to the rank basics of decompression theory.

 

[Dan_P]

Are you freaking serious? THAT is physics, pure and simple.

If not accounting for another baseline atmospheric pressure is not something of the least question to you, then you best return to the rank basics of decompression theory.

You gave up on scrolling too soon.

Further yet, consider the implications of what you're saying.
At 2.000m, you're looking at ca. 0,8 bar.
That means the delta relative pressure difference on ascending from 3m to 2m across sea level (1,3 bar at 3m) and 2.000m altitide (1,1 bar at 3m), is less than 1,5%.
The impact of that on an ascend is about as significant as a burp.
If that little difference is what's winding you up in terms of decompression, you'd never do a repetitive dive, ever. Or dive in cold water, for that matter.
Besides, you're talking about, say, making a pressure drop from 6,0 bar to 1,0 bar versus making a pressure drop from 5,8 bar to 0,8 bar. The total difference is still 5,0 bar. Saying there's a difference in those two dives in terms of bubble propagation equals actively advocating the significance of Boyle's Law on micronuclei (read: deep stops).

So, is Ratio Deco not emphasizing deep stops enough, is that your point?

 

[boulderjohn]

his was after the guy who made RD left that outfit, yes?

You did mean to say after he was fired, didn't you?

 

[boulderjohn]

Further yet, consider the implications of what you're saying.
At 2.000m, you're looking at ca. 0,8 bar.
That means the delta relative pressure difference on ascending from 3m to 2m across sea level (1,3 bar at 3m) and 2.000m altitide (1,1 bar at 3m), is less than 1,5%.
The impact of that on an ascend is about as significant as a burp.
If that little difference is what's winding you up in terms of decompression, you'd never do a repetitive dive, ever. Or dive in cold water, for that matter.

Busy now--get to it later.