Riding Blind with your DSMB reel

[JohnnyC]

Once you descend past 80 feet, most everyone is incapable of using the system "as designed". People rail about the possibility of a PDC failure, yet the human brain fails all the time and consistently so with depth. Denial is not a good strategy in dealing with this. In short, the system can't be reliably used by the average diver. Ergo, the system fails regularly in it's execution. It's too much for the narced mind to deal with and keep up with all the other tasks.

You can contend that a bomb is safe as long as you can run fast enough when you set it off. But when people are regularly injured while trying to follow those instructions what do you do? Blame the people or stop using that bomb? Too many people are being injured with RD for me to ever feel comfortable with it's use. Playing Russian Roulette is not my idea of fun.

It's clear that you don't have a solid understanding of Ratio Deco. He's a general refutation based on the simplest form.

Let's use a 1:1 ratio, good for 45m for 30m just as a baseline. You're not doing ANY real math below an END of 9m/30ft. I don't know a single person who gets narked at 9m. Literally no one I've ever dived with has reported symptoms of nitrogen narcosis that shallow. At MAX depth, your END is 26m/85ft. If you can't take roughly 3/4's of that as your "deep" stop (which puts your END even shallower), you should not use Ratio Deco as an ascent strategy. Now why do I say all of this? Because using Ratio Deco REQUIRES using standard gasses!!!!! In this case, 21/35. 35% helium makes you pretty clear headed at the depths where the 1:1 ratio is functional, at the depths where you actually figure out that you've got 15 minutes worth of stops to spread over 21m-9m, and another 15 at 6m. That's literally as difficult as the math is.

Again, if you cannot dive within the framework that the system was designed for, you should not be trying to shoehorn your diving into that system. It doesn't work, it breaks, which is why boulderjohn's friends got bent. They were not capable of diving within the system.

Who are these people "regularly" getting bent by using Ratio Deco correctly? The system cannot be used by the "average" diver because the "average" diver still needs some 19 year old 100 dive DM to hold their hand. And the "average" diver still gets bent riding a Suunto to the NDL. The diver who is using Ratio Deco shouldn't have any problem with any of it. Seriously, it's not rocket surgery, it's 3rd grade math in 30 feet of water, and it's the ability to maintain a reasonable ascent rate.

You are missing the fact that the human brain and their ability to do these computations is very much a part of the system, just as the processing unit in a computer is part of the system.

No no, you're missing the fact that your friends screwed up the system. The math is not hard, and if they were incapable of doing the VERY basic math required at such shallow narcotic depths, they shouldn't be trying to use a system they do not understand and are incapable of using correctly.

 

[The Chairman]

It's clear that you don't have a solid understanding of Ratio Deco

People regularly get hurt using it and trying to use it. People very seldom get hurt using a PDC or tables. What more do I have to understand? A good friend is missing three fingers from playing with homemade gun powder. Guess, what? I understand just enough about homemade gunpowder to stay the hell away from it.

Here... let me fix this for you:

they shouldn't be trying to use a system

that doesn't work ALL of the time.

 

[PfcAJ]

People regularly get hurt using it and trying to use it. People very seldom get hurt using a PDC or tables. What more do I have to understand? A good friend is missing three fingers from playing with homemade gun powder. Guess, what? I understand just enough about homemade gunpowder to stay the hell away from it.

Yes yes, stick your head in the sand rather than explore the possibility that maybe...just maybe... you're wrong.

 

[JohnnyC]

People regularly get hurt using it and trying to use it. People very seldom get hurt using a PDC or tables. What more do I have to understand? A good friend is missing three fingers from playing with homemade gun powder. Guess, what? I understand just enough about homemade gunpowder to stay the hell away from it.

Here... let me fix this for you: that doesn't work ALL of the time.

​

Who?! Who is regularly getting hurt using it or trying to use it?! Who is getting hurt? If what you say had ANY basis in reality, it would be ALL OVER every dive forum on the internet and it's just not the case!

Blaming a system for hurting people, who don't know how to use it in the first place, isn't the fault of the system! It wasn't the Optima that killed Wes Skiles, it was the fact he didn't know how to use it!

 

[Bennno]

A good friend is missing three fingers from playing with homemade gun powder. Guess, what? I understand just enough about homemade gunpowder to stay the hell away from it.

And you're blaming the gun powder and not your friend?

 

[boulderjohn]

If they aren't able to keep track of their average depth correctly (which you admitted they didn't), if they cannot perform a proper ascent correctly (which you admitted they didn't), if they miscalculated their decompression obligation (which you admitted they did), I'm still not clear on how their mistakes are the fault of a system that they were clearly using outside of the parameters of the design. If they can't do it correctly, they shouldn't be using it.

So, to summarize what you are saying, if a diver is not certain he or she can accurately maintain a running average of their average depth, might be capable of making errors in their ascent rates that that they might fail to account for when they plan their ascent profiles, might make mental errors calculating that profile, and might add times inaccurately as they do their stops, then they should not be using ratio Deco. I agree.

On the other hand, when I was in that system and being forbidden even to carry a computer in its full working mode, we were told that we should not use computers because they are capable of making errors, and the clear implication was that our minds are not capable of making such errors. So there seems to be a contradiction in that teaching point.

this discussion reminds me of Irwin Mainway arguing that it was perfectly OK for children to play with broken glass--after all, if they are too clumsy to handle it safely, it's not the fault of the broken glass.

Watch Consumer Probe: Irwin Mainway from Saturday Night Live on NBC.com

 

[boulderjohn]

Who?! Who is regularly getting hurt using it or trying to use it?! Who is getting hurt? If what you say had ANY basis in reality, it would be ALL OVER every dive forum on the internet and it's just not the case!!

Well, it would be about half the people I used to dive with when I was trained to dive that way. Back then I happened to mention this in a ScubaBoard thread, and I got a message from the agency with which I was then training telling me that if I mentioned it again I would be reported to PADI for disciplinary action for writing something disparaging of an agency. (PADI professionals are forbidden to publish disparaging remarks about other agencies.) That was the final straw that made me drop out of that agency.

I just finished doing trimix certification for someone who used to dive with that group back when I was with it and for a while after. He quit because of this, feeling it was too dangerous. While he was training with me, he said that the only people he knew in his life (with lots of dives) who ever got DCS were in our group doing Ratio Deco.

 

[PfcAJ]

Well, it would be about half the people I used to dive with when I was trained to dive that way. Back then I happened to mention this in a ScubaBoard thread, and I got a message from the agency with which I was then training telling me that if I mentioned it again I would be reported to PADI for disciplinary action for writing something disparaging of an agency. (PADI professionals are forbidden to publish disparaging remarks about other agencies.) That was the final straw that made me drop out of that agency.

I just finished doing trimix certification for someone who used to dive with that group back when I was with it and for a while after. He quit because of this, feeling it was too dangerous. While he was training with me, he said that the only people he knew in his life (with lots of dives) who ever got DCS were in our group doing Ratio Deco.

The rest of the story is important here regarding altitude.

Again, if your RD doesn't equal the tables you're wrong.

 

[boulderjohn]

The rest of the story is important here regarding altitude.

Again, if your RD doesn't equal the tables you're wrong.

You are correct--the dives we were doing were at altitude, and the agency contended (and still does, I believe), that altitude does not matter.

On the other hand, the only instructor I know for the "other" agency also teaches that altitude does not matter, and RD does not have to be adjusted for it. In saying that, he is out of step with Jarrod Jablonski who told me specifically that altitude does matter and RD should not be used at altitude because it has never been tested there.

 

[boulderjohn]

By the way, there might be a simple reason that discussions about DCS and RD are not that prevalent: there is not as much of that going on as ScubaBoard readers might expect.

When I made the decision to leave UTD and RD behind, I crossed over to do tech training through TDI in South Florida. There is a lot of diving going on there. When I talked with my new TDI instructor there and told him that my background was with UTD, he had no idea what I was talking about. He asked me if I didn't mean UDT, another tech agency in that area run by Bob Sheridan. I told him the origin of the agency. He had a vague memory of having heard of GUE and DIR, but he did not really know anything about them. He had never heard of ratio Deco, and I had to explain the concept to him. I was amused in reading the TDI materials, because there were sections that were obvious attacks on DIR and George Irvine especially. My instructor had no idea, and I had to show him the DIR materials that were being attacked so he could see the references.

In a month of diving, with maybe 15 days of diving with several different operators and boats, and with an untold number of tech divers who were also on those boats, I found exactly one person who knew what GUE was, and I found no one who had ever heard of UTD. Bob Sheridan was amused--he had never heard of it and was gratified to learn that his UDT was well known enough that people were often correcting me when I named UTD.

In the years that followed, I have done hundreds of dives, both recreational and technical, in that area. By far most in the last years have been through an operation that identifies itself as a GUE Instructor Development Center. When its employees dive, they all use computers to plan and expecute the dives. On the tech dives, the DMs go around to talk to each group of divers to ask for their planned run times, and I almost always watch the process out of curiosity. I don't recall ever seeing anyone on any of those dives who was not using a computer, so I assume there was no RD being done by anyone.