Deep Air - Here we go again....

[muddiver]

This a thread in the technical diving subforum. Most agencies now a days agree that diving air beyond recreational limits has to great of a risk and therefore recommend trimix.

I think doing something recognized as dangerous when there is a safer option is by definition stupid.

Yes, and one of the agencies that I have studied through even goes as far as to state that their certification is only good to 100 fsw due to the effects of narcosis beyond that depth. I don't completely agree with that because I have been deeper than 100 fsw on air for recreation (and work) and I did not notice any serious effects.

On the other hand a majority of agencies still use the old "recreation limits are to 130 fsw" which originated from the operational limit of the old double hose regulators. That completely ignores the physiological effects of Nitrogen because it extends the use of air into the limits of narcosis.

Trimix is still considered an extreamly advanced form of diving and I do not see the main stream scuba agencies moving to teaching its use deeper than 100 fsw where it should be.

 

[Slamfire]

Your statement "if you don't dive trimix you're stupid" makes it seem as if "black suited DIR/Tech Diver"s say helium must always be used (which is what I meant by picking certain parts, removing the qualifying statements, and applying them indiscriminately). Those posts you quoted are clearly in the context of deep dives.

Good clarification. Which brings me to something that's bugged me for a while. The last time I read UTD training standards they had 100 as the max END. I know the document is written in the context of training, but wouldn't that also imply that according to this training anybody going below 100' should be on He? I've always thought this is too conservative. Why would I have to pay a $70 gas fill to go photograph cloud sponges at 124' when I can get a 28% fill for $15?

To be fair I asked a local UTD instructor about this and his reply was that he does not feel comfortable dictating to people what their max END should be. I am not DIR trained. I chose to go TDI partly because of things like this low END comfort level. I routinely dive with DIR (GUE/UTD) trained people. And I have to say, in the real world we do not have the kind of animosity reflected in this thread.

One of my GUE trained DIR diver buddies recently told me that when he dove Truk Lagoon he did it on air. I chastised him saying that's not DIR. To which he replied that he was not going to pay the prices of He at Truk. I have no idea how long ago his deep air dives were, but I thought it was interesting to note that on his SB profile he also had TDI as one of his certification agencies. Which makes me think he probably also had deep air training.

I think DCBC's point is not that air is superior to He, or even that He is bad, but rather that deep air training can be a good thing.

 

[Blackwood]

The last time I read UTD training standards they had 100 as the max END. I know the document is written in the context of training, but wouldn't that also imply that according to this training anybody going below 100' should be on He?

To my understanding, the characteristics that went in to establishing standard bottom* gases were: ease of blending**, 1.4ATM maximum PO₂, and 100' maximum END (it ranges between 90 and 100 at MOD for the various gases).

So yes: that's the training, and I believe your reading is correct. However rigorously students adhere to it outside of training is a subject for them and their team.

I don't know about UTD's policy towards instructors, but I was told by a GUE instructor that he is expected to respect the maximum END at all times (excepting emergencies), not just while teaching. In fact he can lose his job if he's reported intentionally breaking it.



* I suppose it's worth noting that the deepest standard decompression gas reflects a 1.4ATM maximum PO₂ and 112' maximum END.
** This dates back to when the only way to get trimix was to putting Helium in their cylinders and topping them off with banked gas.

 

[MaxBottomtime]

Umm, she would be about 60 now.

My fiancee is 61. Some things get better with age.

 

[Slamfire]

I don't know about UTD's policy towards instructors, but I was told by a GUE instructor that he is expected to respect the maximum END at all times (excepting emergencies), not just while teaching. In fact he can lose his job if he's reported intentionally breaking it.

I never said that he breaks the 100 max END. He didn't even say that it was ok to break the max of 100 END. All he said was that he was not comfortable telling people what their own personal max END should be. If there were a diver who was not confident in himself going below an 80 END, he wouldn't feel comfortable imposing a personal END of 100. He was also replying to me. Me not being a student of his or UTD and the instructor being fully aware of that.

So yes: that's the training, and I believe your reading [re the max 100END] is correct. However rigorously students adhere to it outside of training is a subject for them and their team.

If such student were not exposed to any other training agency, then going below 100' without breathing He would effectively be diving outside the parameters they trained to. In this situation I can see DCBC's point that having some deep air training would be helpful. After all the commonly accepted max depth of non-technical recreational diving is 130', not 100'.

 

[Mark Michaud SELAUSAR]

You Sir are mistaken. Thousands of commercial divers are working deep air as I type this.

Most of the deep commercial guys (a bunch) I know would rather dive air til they can't. Helium comes in after that. Each give a long list of the downsides they encounter using helium too shallow, when air can still work. I have to guess there is something to what they say.

Me, I don't go much past 150 anyhow. Usually 32% to 120 and then a nitrox mix that puts me at 1.4 ppo at max depth.

 

[Blackwood]

I never said that he breaks the 100 max END. He didn't even say that it was ok to break the max of 100 END.

Sure, I just thought it was interesting. Completely different subject matter (GUE not UTD, and Instructor Corps not Students).

If such student were not exposed to any other training agency, then going below 100' without breathing He would effectively be diving outside the parameters they trained to. In this situation I can see DCBC's point that having some deep air training would be helpful. After all the commonly accepted max depth of non-technical recreational diving is 130', not 100'.

I don't know about that.

It seems to me the relatively few people who train with GUE and UTD do so because they agree with the philosophy, not because they stumbled across a shop and decided they wanted to get certified. Someone who puts enough thought into going with either of those agencies is likely going to put the same level of thought into their actual diving and not expressly rule something in or out because of their training history.

I was trained with 100' maximum END, but am willing to plan deeper depending no the circumstances.

 

[rjack321]

After all the commonly accepted max depth of non-technical recreational diving is 130', not 100'.

Doing something minorly stupid in a single tank no-stop context is probably not going to be fatal (running out of gas and embolism excepted). Doing something stupid at much greater depth or END in a decompression situation with a pile of additional gear and gases which also have the potential to kill you is much more serious situation which also requires much clearer thinking.

 

[Sloth]

Every tech diver I know has their own personal END that they are comfortable with. Some are ok with END's beyond recommended ranges. All of the tech divers I know have a very well grounded understanding of these risks. If they choose to dive beyond safe diving limits then that is on them.

For me, my personal END is 110 if I am not doing any wreck penetration. If I am doing some form of wreck penetration then I like to have an END around 90 or 100 at the max. Some divers will extend their own personal END to greater depths outside of training recommendation.

Regardless, all divers getting into technical diving should not be mislead by their instructor to the inherit risks of deep air diving. Their is no such thing as training a diver to dive deep on air. Everyone has their own susceptibility to nitrogen narcosis which can be buffered by repeated air dives. Unfortunately due to the denial effects of narcosis each diver is their own worst judge of whether they are narced or not. The only thing an instructor can do is point out that they may be too susceptible to narcosis to dive deeper. Unfortunately, there are two problems with this. First, if the instructor is judging diver A's susceptibility to narcosis at depth and he is on air then his judgment is also suspect. Second, each individuals susceptibility to narcosis is variable and can change day to day.

In a nutshell, an instructor teaching someone to handle narcosis is like a drunk teaching someone to handle their alcohol.

 

[Slamfire]

Another thing that bugs me a bit about pushing He diving at say ...110' is the possibility of monetary benefits/motivation on the part of the LDS doing the training. Even if they say the profit margin is lower than regular nitrox fills -- 5% profit from a $70 trimix fill is still more money than 15% profit from a $15 nitrox fill. We're all familiar with the criticism GUE has gotten because JJ is affiliated to Halcyon, so there's no point in me going deeper into that.

The DIR philosophy has so many great points. One that I like very much is that of the "thinking diver" that doesn't allow his computer to plan the dive for him and replace his brain while diving. Question whatever the computer is spitting out and make sure that whatever it is saying makes sense. Similarly, why should I blindly follow or accept training standards that may not make full sense to me. Diving He at 110' doesn't make much sense for me, and as I said before, it is one of the reasons why I chose not to train through UTD.