Ongoing discussion of Ratio Deco

[rjack321]

I am working on the excel version right now.

PM me a email address and I'll send it when I'm done. T1 only so far.

 

[lamont]

same comments could be made for:

"DecoPlanner, then shape the stops and add deep stops-- but not quite the same shape as an RD 'S-curve' -- more like adding minutes at the 70 foot stop, rolling minutes in from the 80 stop to 70 etc."

i don't know why decoplanner doesn't have a button to do that for you...

 

[Meng_Tze]

I think that any capable programmer, myself not being one, could write some code that would implement the RD diveplanner based on the specifications described in the ratio deco pdf. It's mainly simple math.

I could probably write simple web based application in php or perl on for profiles within 100 - 150 range.

But that would not give it scientific merrit, it would merely as you say be an application of some arithmetic. There is no RD algorithm, nor shall there be one in the very near future........heck RGBM is still under development...... and Dr. Wienke has been working on this, what 20 years or so? When was the last time there was a new compartment added to the buhlman algo? We keep learning about deco every time a (properly monitored) diver bends or clears a dive in a scientific setting, under controlled circumstances. To present deco, but more over RD as scientifically accurate....

To call something scientifically accurate you have to be able to repeat the tests, and more over be able to predict accurately what future outcomes will be based on your knowledge of the subject.

Yes the diver will come up safely if you give him enough fudge factor............but NO ONE has been able (or maybe it is willing) to say WHERE the line lies between too aggressive (guaranteed DCS) and just not aggressive......If this can be assessed and predicted on every dive with every person... then you have accurate science I am not saying there is no non accurate science (medicine), but that has been around for many centuries and is based in critical parts on scientific studies and accurate sciences (chemistry).... diving and especially deco profiling has not been around that long.........................it is coming I am sure, but we should not try to pass 'gut feeling', lucky shots, 'lets stay within the well established limits of known profiles' as as scientific....

It still is black magic

 

[lamont]

But that would not give it scientific merrit, it would merely as you say be an application of some arithmetic. There is no RD algorithm, nor shall there be one in the very near future........heck RGBM is still under development...... and Dr. Wienke has been working on this, what 20 years or so? When was the last time there was a new compartment added to the buhlman algo? We keep learning about deco every time a (properly monitored) diver bends or clears a dive in a scientific setting, under controlled circumstances. To present deco, but more over RD as scientifically accurate....

To call something scientifically accurate you have to be able to repeat the tests, and more over be able to predict accurately what future outcomes will be based on your knowledge of the subject.

Yes the diver will come up safely if you give him enough fudge factor............but NO ONE has been able (or maybe it is willing) to say WHERE the line lies between too aggressive (guaranteed DCS) and just not aggressive......If this can be assessed and predicted on every dive with every person... then you have accurate science I am not saying there is no non accurate science (medicine), but that has been around for many centuries and is based in critical parts on scientific studies and accurate sciences (chemistry).... diving and especially deco profiling has not been around that long.........................it is coming I am sure, but we should not try to pass 'gut feeling', lucky shots, 'lets stay within the well established limits of known profiles' as as scientific....

you are confusing a whole lot of things. i never claimed i wanted an algorithmic implmentation of RD or shaped-GF curves to make them 'scientifically accurate'. i also never claimed i wanted them fixed in stone and never be under any development. but without having a better specification for how divers are fudging their deco schedules then i don't see how you get to scientific accuracy. to be scientific you need to all agree about what you're talking about, and if you can't agree there can be no science. if you can agree what you're talking about it should be possible to do a concrete implementation. even if you don't agree what you're talking about it should be possible to do concrete implementations that differ and then get into a scientifically-oriented discussion over the concrete differences.

i do know the differences between precision and accuracy. all i'm calling for is more precision in the language being used to discuss decompression strategies. i'm not claiming that by being more precise in specification that it leads to more accuracy.

 

[cool_hardware52]

to be scientific you need to all agree about what you're talking about, and if you can't agree there can be no science. if you can agree what you're talking about it should be possible to do a concrete implementation. even if you don't agree what you're talking about it should be possible to do concrete implementations that differ and then get into a scientifically-oriented discussion over the concrete differences.

That's perfectly reasonable. Distile the rules down to an "equation" so there is a "finite" protocol to examine.

Tobin

 

[Meng_Tze]

@ Lamont,
I do not claim the things you referred to in your response. I was responding in general to this thread. Sorry if it came across as pointed to yourself

 

[limeyx]

' wrong, wrong, wrong attitude' according to Phil K.....

(I was out diving two days, so just catching up on this thread. )

Diving, what's that?

 

[limeyx]

same comments could be made for:

"DecoPlanner, then shape the stops and add deep stops-- but not quite the same shape as an RD 'S-curve' -- more like adding minutes at the 70 foot stop, rolling minutes in from the 80 stop to 70 etc."

i don't know why decoplanner doesn't have a button to do that for you...

EDIT: I have been informed that my post here was poorly worded. This was not supposed to sound like a slam on GUE for being lazy/profit driven, but that was not my intent.

Sorry for the confusion.

 

[grazie42]

Since it seems I have a whole host of people conserned for my safety (and sanity?) let me assure you that the day I dive a RD-profile is a long way off...unless of course it is similar to v-planner one...doesen´t look like that´s likely to happen any time soon

I´ve given this some thought (beware) and I guess my "just jump in" and "modify a plan" approaches really are the same thing and the division was just semantic(?)

You can just "jump in" with RD because all the constraints are given...
-What I do on recdives when I consider my options is to evaluate my status in relation to the constraints of the dive (desired profile/max time etc).
-The same thing is what people diving RD do, they evaluate their status and options against the constraints that RD sets for the dive (RB, max avg. depth, max time, max deco).

Just as on a recdive with new buddies you´d need to say "No deeper than 25meters and I like to take it slow from 12m and up and spend a minute or two on 9 & 6 meters as well" if thats what you want to do. With your regular buddy you´ll have a "standard depth" and a common ascent procedure that you use on every dive, you know eachothers SAC so you anticipate what profile changes do to your buddies status as well as your own and you almost always "turn the dive" simultaneously...

While it may seem to an outsider as if you and your regular buddy "just dive" and that you and your new buddy are planning a dive with limits on the changes you´ll allow, you´re really doing the same thing in both instances, the only difference being that the "constraints" are explicit in one case and implicit in the other...

The point of DIR & RD is to make as many things as possible implicit so that it "frees RAM" to focus on the important things (the stuff that sets a particular dive apart from the "general dive") and to make it possible to do not only with your regular buddy/team but with any DIR-team after a quick check that you´re "the same DIR". It means a redistribution of planning time and thought from "annuity" to "investment" to use NPV-terms...

Makes sense? Or am I just making more people cringe?

Edit: Apologies to those having to read the same stuff twice but there are different participants and the responses obviously do differ somewhat (noone´s called me "really dumb" here yet ) so I believe it worthwhile...

 

[rainman_02]

Because then GUE might have to actually do the same validations on it that are done on Buhlmann before they can sell it? Cheaper to sell something that someone else validated

A few months ago I found a big nasty error in Deco Planner. I emailed the support and never heard back. There's still an error in the program, and it seems no one cares. Scary.