Ratio Deco

[PfcAJ]

I've clearly explained how gue uses ratio deco and how it's different. I've clearly explained where gue gets its numbers from. I'm just repeating myself at this point.

S curves, oxygen window, and deep stops are not supported by decompression science literature. You're confusing science with pseudoscience, right along with blood cell dust.

the examples shown of folks getting bent using AG's methods aren't good enough for you. That's fine. You can continue to "ignore" things like altitude and not track repetitive dives with accuracy (we all know that total inert gas washout takes longer than 1hr).

But dont pretend like what you're teaching or advocating is 'scientific' or smart. It's not.

 

[ajduplessis]

The UTD RD thing is potetially dangerous! Yes, I added a ton of suger to this statement.

 

[Slamfire]

I have a friend here in the lower mainland. He is UTD Tech Gold certified. He got bent twice on 21/35 + 50% RD profiles. These were inner ear hits, almost exactly 1 year apart from each other. He now stays above 130ft and within min deco. These were sea level dives in the lower mainland.

 

[LiteHedded]

I have a friend here in the lower mainland. He is UTD Tech Gold certified. He got bent twice on 21/35 + 50% RD profiles. These were inner ear hits, almost exactly 1 year apart from each other. He now stays above 130ft and within min deco. These were sea level dives in the lower mainland.

i'm sure it was his fault and not the profile.

 

[Adobo]

I have a friend here in the lower mainland. He is UTD Tech Gold certified. He got bent twice on 21/35 + 50% RD profiles. These were inner ear hits, almost exactly 1 year apart from each other. He now stays above 130ft and within min deco. These were sea level dives in the lower mainland.

What was different about your friend's dive profiles? Did he follow a ratio deco guideline instead of a traditional algorithm to determine his deco obligation (and was ratio deco showing something different than what buhlmann or VPM was saying)? Or did he implement S curves as opposed to a more linear type of distribution of his stops? Did he do both?

Because if he did neither, I don't know that we can necessarily attribute the bend to ratio deco. Am I making any sense?

---------- Post added July 23rd, 2015 at 10:24 AM ----------

I think the articles give a good background and the science around RD, you did read it and not just watch the video, right? I'll try to dig up more of the study, based on Buhlman, incorporates S curves and more details. I believe there is a chart that shows the variance between Buhlman and RD. Yes, John mentioned 6 of his group, I recall that long post awhile ago that, as I've asked you before, couldn't be solely attributed to RD. So, for the forth time, you say it's dangerous, it hurts people.....proof? You still haven't answered where GUE has developed and proved RD? Is it impossible for you to say you don't know something. I don't know how GUE did, I don't know where AG got his idea.

Where has it been said that RD doesn't cover decompression algorithms? Again, you are under the misconception that there is no algorithm.
Also, you say "posters", no, one poster, John, and again that was a long post and again it's anecdotal. Still waiting for your "LITERALLY" published data of accidents attributable to RD.

I don't know if I am reading the same article you are. The one I see is devoid of any actual detail regarding the "study". 30 divers not getting bent when using ratio deco - that in of itself is not science, is it? I mean, there is no explanation of what blood cell dust is (first time I have heard of it, though to be fair, I am not all that versed on decompression), no details on how they determined that there was no "activation of the immune system" and no details of how they determined bubble formation and how those bubbles were eliminated. And certainly, I don't know what qualifies as "showing massive advantages" when implementing ratio deco.

I mean, were they able to test both groups for these indicators after each and every dive? For 60 divers? For 5 years? I tried to find the video on line hoping the video had all these details. Sadly, all I could find was another short clip by Andrew which again was missing the pertinent details. Maybe you can provide the link because I can't seem to launch it from the PDF.

At any rate, I personally am willing to give this ratio deco thing the benefit of the doubt but, none of the materials you have provided so far seem to have any information that supports the idea that ratio deco is valid outside of the areas where ratio deco intersects with other deco strategies.

 

[boulderjohn]

I Yes, John mentioned 6 of his group, I recall that long post awhile ago that, as I've asked you before, couldn't be solely attributed to RD.

You do realize, don't you, that there is a logical problem in this thought seqeunce?
1. No one has ever been bent using ratio deco.
2. In the cases in which divers were bent using ratio deco, something else had to be the cause, because you do not get bent on ratio deco.

It is called begging the question, the fallacy in which the conclusion is assumed in the premise. It is impossible to attribute any DCS case to ratio deco if you assume all ratio deco DCS cases must be caused by something else because ratio deco itself does not cause DCS.

Note that the qualifications regarding the degree to which the diver followed ratio deco perfectly or the degree to which a medical condition (like PFO) may have been a factor also applies to all other decompression programs. If you look at the rate at which DCS occurs using U.S. Navy tables, PADI tables, VPM, Buhlmann, DCIEM--any of them--the published rate of DCS incidents includes people who probably had PFOs or did not precisely follow the schedule. When a friend of mine got DCS on a set of dives we did (using ratio deco, BTW), we reported to DAN our precise dive profile, according to what it said in my wet notes. DAN was impressed--they said they rarely get anything that detailed. Of course, how accurate was it? How accurately did we hit the precise depths and times?

Any system like this is subject to the vagaries of human error. For several years after I stopped using ratio deco, I used VPM with a bottom timer instead. We would do the standard process of writing down the profile for the dive we planned to do plus two contingencies. In some environments, it is easy to hit your planned maximum depth or average maximum depth, but in others it is almost impossible. You can't really predict what you are going to do on a wreck, so you are always a little off to start with. Then you follow a precise plan up to the surface. How closely did you follow it?

The point is that all decompression algorithms that use a system like this are subject to human error, so all statistics on their DCS percentages include cases in which the diver had a PFO or in which the diver did not follow the plan precisely.

 

[PfcAJ]

I found this from UTD
http://www.dyk-dir.dk/1to3_rd.pdf

At the extreme side of things, 290' for 120mins on 12/60 with 3 deco gases (which is dumb to begin with from a gas management perspective) the difference between "ratio deco" and Buhlmann is absolutely absurd. Even the VPM difference is preposterous.

RD - 380mins
Buhlmann 20/85 - 719mins (I would sign up for this dive but would fiddle with the GF low and high a bit and add another gas which drops the time down to ~600-630mins and gives more options)
VPM - 500mins (I wouldn't sign up for that even with adding a 4th gas)

This is a REALLY big dive, and something that probably 99.9% of divers will never even approach, but serves as an example of the absolute nonsense UTD is teaching. Dangerous. Even with much shorter bottom times and shallower depths, the differences in ascent time between RD and Buhlmann is ridiculous.

 

[LiteHedded]

I found this from UTD
http://www.dyk-dir.dk/1to3_rd.pdf

At the extreme side of things, 290' for 120mins on 12/60 with 3 deco gases (which is dumb to begin with from a gas management perspective) the difference between "ratio deco" and Buhlmann is absolutely absurd. Even the VPM difference is preposterous.

RD - 380mins
Buhlmann 20/85 - 719mins (I would sign up for this dive but would fiddle with the GF low and high a bit and add another gas which drops the time down to ~600-630mins and gives more options)
VPM - 500mins (I wouldn't sign up for that even with adding a 4th gas)

This is a REALLY big dive, and something that probably 99.9% of divers will never even approach, but serves as an example of the absolute nonsense UTD is teaching. Dangerous. Even with much shorter bottom times and shallower depths, the differences in ascent time between RD and Buhlmann is ridiculous.

sign me up

 

[PfcAJ]

I've got a wheelchair on standby.

 

[Doppler]

The refreshing thing about reading this thread is there are more people (very experienced people) with unanswered questions than there are supplying answers -- well, what they believe to be answers -- and the folks posing questions are not buying any of them.

By the way, I'd say the ratio on that is about six to one.