You are absolutely correct. Most don't care. I don't think this thread will hold much interest for them. Do you? There are plenty of threads on this board to interest them.
NDL
- Thread starter Uncle Pug
- Start date
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You are absolutely correct. Most don't care. I don't think this thread will hold much interest for them. Do you? There are plenty of threads on this board to interest them.
I certainly have no interest in rushing anyone into technical diving or anything else for that matter. This thread though is (or was) about the significance on the "NDL" and other factors that can effect it. Do you remember being warned to avoid certain profiles in your OW class? You should have been told to avoid profiles like "saw tooth", "bounce dives" and so on. That's in part what we're talking about here. It seems though many throw it all away and only keep the NDL. Knowledge is power so they say.
I certainly would never try to make you do anything. Why don't you like it that we're talking about diving? There is a travel section on the board. They won't tire you with dry talk about decompression theory.
You won't gain skills without putting some thought into what your doing. It takes some effort to build skill not just breathing underwater. I know lots of people who have been diving for many years. They show off their computer printouts at parties. I see the rapid ascents from 80 ft to find the boat and the immediate ascent back to depth to use up the remaining gas and bottom time. Do you think that ascent and descent can effect teir effective NDL? The OW text says so. Far be it from me to interupt their fun and rush them by suggesting that I wouldn't dive that way.
If trading information and ideas is rushing people then yes many of us are guilty. What would you like to talk about?
I don't think there is a problem.
There are smoking and fitness threads on the board. It sounds like you may have something to contribute there.
I know what you mean. Didn't you just participate in a thread praising NAUI for adding a "deep stop" to their program? Sounds like part of what we're talking about here. Does it make for a better profile? Does it make the NDL a better NDL? Does it reduce bubbling? Sounds alot like what we're talking about here. Are you saying that the NAUI deep stop is rushing folks toward tech diving? Are they being snobs about it?
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I said...
BTW, I sent a get well e-mail today to a guy who, last I heard, was still walking with a cane a month after a dive where he stayed within the limits of his computer.
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You make it sound like it was just bad luck or that some one else did it to him. Nothing in life is completely certain but I think there are a number of things he could have done differently that may have resulted in a better outcome. Given the way things turned out it might be worth a try don't you think?
I said...
BTW, I sent a get well e-mail today to a guy who, last I heard, was still walking with a cane a month after a dive where he stayed within the limits of his computer.
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You make it sound like it was just bad luck or that some one else did it to him. Nothing in life is completely certain but I think there are a number of things he could have done differently that may have resulted in a better outcome. Given the way things turned out it might be worth a try don't you think?
Uncle Pug,
I would suggest that you limit these subjects to a diving forum.
I would suggest that you limit these subjects to a diving forum.
Actually Mike, I am not sure you do. I have no problems with NAUI's acceptance of the rule of halves... heck, I follow a profile more conservative than even that when I dive deep. I was worried that someone would just take offence that I disagree with them. Please dont twist my words to make a point. Its not nice.
I do have a problem with the attitude towards the NDL. They were developed with more resources than we have available to us and more than that... they just work. That someone just blithely states that they are not useful or don't exist just blows my mind. Sure, I understand (and agree) with the premise the Pugster was taking it with, but others have taken it FAR over that edge. The problem ISN'T with the NDL... it's with the diver. Why throw out the concept instead of just teaching the diver to dive it responsibly? Why throw out computers instead of using them as a tool.
Take fer instance your diver with the ascent/descent problem. That is the best use of this device. Now YOU and I can look at a diver we have never been in the water and advise them on how to dive safer. I know for a fact that I used to blow off safety stops ans ascended way too fast until I got my computer. I would feel ashamed to show some of my early dive profiles... but the computer showed me my errors. Where was my instructor? I didn't have one at the time... but the computer gave me a way of analyzing my own dive profiles and CHANGED THE WAY I DIVE. You can dismiss the technology all you want... it is useful and is here to stay.
Of course. If I believe Dr. Deco it's never just bad luck. What I understand from Dr. Deco is that if you follow the tables to the letter and don't do anything to pre-dispose yourself to DCS (heavy work on the bottom, heavy post-dive lifting etc etc - he has a nice list) then the chance of a DCS incident is virtually zero. In fact I think he said something to the effect of "zero, nada, zilch....." He wasn't saying that it doesn happen often, he was saying that it doesn't happen *at all* in the lab. Thats the way the NDL's were set (as I understand it).
Which means that all "undeserved" hits should be explainable in theory. My (superficial) reading of incident reports is that the causes are more often than not, unfinished deco (at least in western Europe). For example, doing stupid things like what Seajay did and then running out of air before finishing deco, which thankfully didn't happen to him but it wasn't far off..... Or wannabe tekkies who are experimenting with unplanned or incorrectly planned deco because they bought doubles and a BP/wing and they think that makes them invulnerable. Fast ascents, "riding the computer" without thinking about your profile and so on probably account for a portion but in my reading, not for the lion's share; at least not where I live. In short all the things you warn students about at the OW level.
Your comment that people remember the NDL and forget the rest is right on the money (I think this is also what UP was trying to say). But this is logical. I mean, how can you train divers who don't care about this stuff to remember "the rest" too? The variables are too numerous and the list of do's and don'ts is too long for most casual divers to (want to) remember. After a few months dry you're lucky if someone remembers to watch their NDL and acent rate let alone the rest. You should ask your friend what he thinks he did wrong. I'd be willing to bet that he won't know and he'll just write it up as "undeserved", while we're learning from Dr. Powell that the idea of "undeserved" is a sort of urban myth.
I obviously don't have any quick-fixes for this either. If I did I'd be rich and famous. What I can see, however, is that most people don't care about this stuff and that like it or not most puddlestompers are going to switch their brains off under water and "ride the comptuer".
Maybe part of the solution is to make computers "zig zag" aware and to air integrate them to sense "heavy work on the bottom", which Dr. Powell suggests is one of the major contributing factors to unexplained DCS. mMaybe part of the solution is to convince OW students that even ONE little bounce is going to kill them so they're afraid to make zig-zags. Maybe part of the solution is to teach computer usage at OW level to address the issue that most people buy a computer before they've been trained how to use it. And maybe part of the solution is to teach a rock-hard maximum of 3 normal ascents per day (maybe even build this into the computers).
But I don't think that the solution is to insist that the puddlestomping public should gain a large base of deco theory so that they can apply their own lateral-thinking in a wide variety of new situations. Some divers will want to learn it but I think that's asking a lot of people who are just out to have some fun and want to know how to do that without too much risk.
And the chances of a DCS incident are about 10000:1 IIRC (deserved and "undeserved") so *anything* you do to try improving this is likely to be statistically insignificant.
Your turn.
I didn't dismiss any technology and I never suggested that NDLs be ignored. What I am saying is that the NDL doesn't in itselfe garantee safety regarless of the profile within the NDL. NDL alone, IMO, isn't enough. The NDL's were developed within certain other constraints like foreward profiles and ascents of a certain speed. I think divers forget that part.
That may be true for a single dive or a limited number of dives in a series. Table testing is less certain for multiple dives over multiple days. The recommendation there is to ease off, skip a day or whatever. Maybe more diver freindly profiles will help too.
Don't forget rapid ascents. They show up in a large percentage of dives that result in injury.
I will ask him. I am very interested in what he thinks since he and I have dicsussed this a little in the past and he knows my take on it.
I'm not looking for a solution.
And the chances of a DCS incident are about 10000:1 IIRC (deserved and "undeserved") so *anything* you do to try improving this is likely to be statistically insignificant.
Your turn.
I don't know if we know what the chances are. The DAN report states that they don't know how many dives are conducted or how many active diver there are. They only know the number of DCS incedents reported. But for the sake of argument lets say your 10000:1 is correct. Do you think it's statistically insignificant to the one? Is it statistically insignificant if it could be easily avoided?
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