trimix training

[Scared Silly]

I plan to take a normoxic trimix class in the

next year and remember doing my AN/DP dives where I was narc'd but good at 140'. We were still on the line - well I was but the instructor had left it. I was not leaving it, I knew I was narc'd and felt like the drunk who was hanging on to the lamp post cause if he did not he was going to fall down. It took a few minutes before I felt like leaving the line. So I guess for me - been there done that.​

BTW I did have enough sense to signal my instructor, get his attention, note that I loopy, and stay on the line. So I guess I was semi functional narc'd diver.

Given the possibility of having to use air in an OOG emergency,

I too would like to have an example of this scenario.

 

[nimoh]

I plan to take a normoxic trimix class in the

next year and remember doing my AN/DP dives where I was narc'd but good at 140'. We were still on the line - well I was but the instructor had left it. I was not leaving it, I knew I was narc'd and felt like the drunk who was hanging on to the lamp post cause if he did not he was going to fall down. It took a few minutes before I felt like leaving the line. So I guess for me - been there done that.​

BTW I did have enough sense to signal my instructor, get his attention, note that I loopy, and stay on the line. So I guess I was semi functional narc'd diver.





I too would like to have an example of this scenario.

I like your signature line....did you write that hanging on the line at 140'?

 

[Wookie]

I was amazed to learn that deep air deco is much shorter for the same dive on 21/35, given the same deco gas. There is a lesson to be learned, but I don't know how valuable it is.

 

[Adobo]

Given the possibility of having to use air in an OOG emergency, I have a hard time seeing how anyone would want to do a basic trimix course without first having dove air at those depths. For more advanced trimix classes, it probably has little to no relevance since as you get into the deeper 200' range, certainly past 240' or so, the risk of tox makes air far less relevant. As for the idea that you can't remember what you learned/did at 180' on air...



Much like EtOH, everyone responds to narcosis differently... but you should at least consider working up to it, as you (a) might be surprised at how functional you are, and (b) may one day find yourself going to 180'+ on air for an emergency and that's not the time to wonder whether it's as horrible as you've been told.

Why would anyone accidentally find themselves at 180 on air? If someone is resolved to use trimix in deep dives (lets say for the sake of discussion that "deep" is a dive that exceeds 130ft), if there was an out of gas emergency while they are still on backgas, they would share trimix, right? And if they are diving air, then the dive would be shallower than 130ft, right?

 

[mathauck0814]

Why would I have the possibility of having to use air in an OOG emergency? On a 180' dive, the choices based on what me and my teammates are carrying would be 21/35, EAN50 and O2, and I have no intentions of finding out what the latter two are like at 180'

So you're saying that if 21/35 weren't an option you'd simply refuse to dive? I'd also much prefer to have a little helium in the mix, but it's hardly impossible to manage deep air diving.

---------- Post added July 19th, 2013 at 01:54 PM ----------

And if they are diving air, then the dive would be shallower than 130ft, right?

Well, technically PPO2 of Air is 1.4 ~187fsw...

 

[Adobo]

So you're saying that if 21/35 weren't an option you'd simply refuse to dive? I'd also much prefer to have a little helium in the mix, but it's hardly impossible to manage deep air diving.

---------- Post added July 19th, 2013 at 01:54 PM ----------



Well, technically PPO2 of Air is 1.4 ~187fsw...

The sensibility of deep air diving is a different topic though.

The question here is, what is the point of doing deep air training as part of a trimix class? Or what is the point of having a pre-requisite for deep air training prior to being able to take a trimix class?

 

[mathauck0814]

The topic of the sensibility of deep air diving is a different topic though.

The question here is, what is the point of doing deep air training as part of a trimix class? Or what is the point of having a pre-requisite for deep air training prior to being able to take a trimix class?

Right - my take is that it's better to have some experience with real narcosis (PPN2 ~4.0) as it can be managed (not overcome, but managed). Helium is only going to get harder to get. As we found out in San Diego last summer, when there's no Helium around to be had - it doesn't matter whether you can afford it or not. So does that mean you're simply not going to dive? I'd rather have some experience to give myself an option rather than just be forced to the sideline.

Whether you get experience in a course or not, I suppose I don't have an opinion on. I do think it's a valid teaching tool (as I said in my first post on this thread) to do two dives to the same deep site to note the difference.

 

[elan]

I do not personally see any value on doing deep air to feel narcosis. I start recognizing it around 50ft be it cold or warm water. So diving to 100ft on Nitrox and then on trimix will give a good idea about the difference between the two. And I do not believe those who say they are not narced at 100ft

 

[Dr. Lecter]

I too would like to have an example of this scenario.

Sure thing: you get separated from your team due to current and low viz on a large wreck in the 180'-240' range, have one of the various problems that can cost you a lot of gas quickly (free flow, injured hose, take your pick) and run into someone like me with double 130s of air and 50% and 80% deco mixes. Is it unlikely to happen? I hope so, for your sake. Is it a real possibility? Yes.

"Rarely is closer to always than it is to never. Always plan for the rare things."

Don't worry though, I'd be happy to offer you the 80% if you're too good to breathe air. You won't use up much of it

Why would anyone accidentally find themselves at 180 on air?

Other than what I just said above, there are dives where you and your buddy may not plan on going deep and therefore both take air, but for some reason one of you is forced lower than intended (downcurrent, sudden wing failure, health issue, wrong/bad gas, take your pick). Are you going to sit at 130' and wave/wait, or go down and help?

 

[Ste Wart]

Interesting topic.

After a poor Normoxic course, I decided to really vet the next instructor I would have in technical diving. So after a few conversations with the potential candidate, I agreed to the hypoxic course, but asked to to a deep air dive to 55m together beforehand. He agreed.

We did the dive and when we entered a large tunnel, the slight darkness (Egypt, Blue Hole if you want to google) got me narced. He sparked me out of it, we successfully finished the dive and deco. Afterwards I then signed on the dotted line for the course.

Because of the bad course and narc incident I insisted that we do a couple of dives at 50m on air during the hypoxic course. My reason for this is that I wanted to know where my skill set lay. Was it in my short term memory or had my lizard brain ingrained it? Thankfully the latter was the case. And despite the natural fog that occurs at those depths my natural OCD and skill practice allowed me to complete the dives safely.

Flash forward: I have since stopped warm water diving and now dive primarily in the UK. Without question I will use mix below 40 metres. However I was grateful for the experience. Now at least I can say that I can do deep air dives and have reasons based on my own physiology, rather than internet dogma, as to why I do not wish to do them again.