1st deep dive (Nitrogen Narcosis?)

[Bubbletrubble]

I've seen that info. But for the primary location where I do my AOW classes doing the deep dive as the first dive of the day on the second day makes more sense. The lake is at altitude (3250ft), the next two dives I do are search and recovery and Buddy skills and assist. Doing the deep dive at 8:30 am and getting it out of the way because I do it as multilevel dive as well and ends up being 45-50 minutes has us oiut of the water by 9:45 and gives us a good 2 hour or more surface interval. The next two dives require alot of attention to detail as well as being physically challenging.

I would not want to have student do a deep dive after them. they are relatively shallow and the final one has a good deal of surface work. In addition it is a popular site and once other groups get there we have others doing their deep dives and still doing vertical descents which quickly turns the vis to crap. I'd rather just have to deal with darkness and not rototillers mucking things up. Also I want all their wits about them and a good night's sleep helps with that. And we dive with tables and they are much friendlier with forward profiles. I do cut tables as well on v-planner.

The final reason is the dives are setup to build on each other skills wise, I offer Advanced Skills, Uw Nav, Night Low vis, Deep, Search and Recovery or Wreck if they want to pay extra to get to a site where we can do them, and Buddy Skills and Assist.
These are the only dives I offer for AOW. Anything else is a different course or class.

@Jim Lapenta: You've listed some reasonable practical/logistical reasons for doing the deep dive first in the day...and adhering to forward profiles. Your previous posts in this thread seemed to imply that reverse profiles increase the incidence of DCS. I wanted to clarify that that isn't the case. I apologize if I misunderstood what you were trying to say.

FWIW, I don't believe that some of the larger instructional agencies are teaching OW students that reverse profiles are bad, per se.

 

[all4scuba05]

and suddenly I heard a voice that I'd never heard.

in my pants pocket ... and the fabric got tight ... I hear a female voice !

I don't even have to rearrange your words. Thanks for the laugh!!!

 

[T. Bix]

However, I have been underwater and actual heard people talking on the surface from a surprising way away...only once and it scared the heck out of me. At the time I did not know what was going on. They were talking next to the side of a boat, and yelling... suspect the hull carried the sound into the water.. but don't actually know.

Right on the mark! I was diving in Oahu a couple of months ago and during the dive I heard fairly distinct rock music, I thought I must be imagining it. I tried to reason through it but couldn't. I knew I wasn't narc'd but just couldn't get my brain around it. I was bothered by this strange noise during our entire surface interval until I asked the boat captain what he usually did while divers were down.......... You guessed it he likes to jam out!! What a relief at least I wasn't hearing opera :serenade:

 

[SkimFisher]

I can honestly say I've never felt narc'd before and I've been below 100' quite a few times. I'm not saying I wasn't narc'd in some capacity - but never felt loopy, happy, anxious, panicked - none of that stuff.

 

[Diver0001]

I can honestly say I've never felt narc'd before and I've been below 100' quite a few times. I'm not saying I wasn't narc'd in some capacity - but never felt loopy, happy, anxious, panicked - none of that stuff.

I went on a chamber ride a couple of years ago and it's a worthwhile experience. One of things that diving in a chamber does is make you acutely aware of the narcosis, much more aware than you'll ever be in the water. I don't know how that works but it does.

Prior to making a chamber dive I'd done many hundreds of deep dives and never felt particularly narced either. After that experience, however, I realized that I just wasn't as aware of how it really felt as I could have been. Something about being in air instead of in water made me able to put my finger on the feeling better.... Since doing that chamber dive I've found that I can "feel" the narcosis better. It isn't any worse than it ever was but I'm able to filter it out better.

I don't know if you would have the same experience as I did, but it might be an interesting thing to try. If you ever have a chance to take a chamber ride I'd recommend it.

R..

 

[DCBC]

I went on a chamber ride a couple of years ago and it's a worthwhile experience. One of things that diving in a chamber does is make you acutely aware of the narcosis, much more aware than you'll ever be in the water. I don't know how that works but it does.

For most people, a ride in the chamber is much less intimidating than an actual deep dive (it's not proactive but a reactive activity). I've found that mental attitude makes a huge difference in how individuals deal with narcosis. This is not to say that the narcosis can be avoided, rather it can be more manageable.

When stationed at DCIEM, I was involved in a number of scientific studies involving nitrogen narcosis. If I relaxed and "allowed" myself to go with the flow, I became much more affected by by narcosis. If I focused on the testing (deeply concentrating on the mission), my results were markedly improved.

I take all my OW students on a ride in the chamber. Like you, I'd highly recommend it to any diver.

 

[SkimFisher]

I went on a chamber ride a couple of years ago and it's a worthwhile experience. One of things that diving in a chamber does is make you acutely aware of the narcosis, much more aware than you'll ever be in the water. I don't know how that works but it does.

Prior to making a chamber dive I'd done many hundreds of deep dives and never felt particularly narced either. After that experience, however, I realized that I just wasn't as aware of how it really felt as I could have been. Something about being in air instead of in water made me able to put my finger on the feeling better.... Since doing that chamber dive I've found that I can "feel" the narcosis better. It isn't any worse than it ever was but I'm able to filter it out better.

I don't know if you would have the same experience as I did, but it might be an interesting thing to try. If you ever have a chance to take a chamber ride I'd recommend it.

R..

Interesting. Thanks for the info.

 

[gcbryan]

I think at the depths where it doesn't seem to affect you all that much it takes a while to become attuned to it. However, once you are able to pick up on it you can recognize it more easily after that.

It doesn't affect me any more or less than it ever did but I am able to realize that it's going on now much more easily than in the past. That's just because it's such a subtle thing.

You may not think you are experiencing narcosis at 100 fsw but you probably "feel" differently at 30 fsw and just attribute that to being back in the safety of the shallows after another enjoyable dive. Or as is the case here with one of our dives...you realize that the "magical" nature of the I-beams at 100 fsw is "magical" in part because of mild narcosis.

If I haven't been diving for a prolonged period, the first time I get back in the water I may not be 100% comfortable (subconsciously) and when I get to 100 fsw I actually get more relaxed. Sure part of this is just getting the dive underway and getting in the "groove" again but a large part of it is mild narcosis. At those depths I don't get the "dark" narcosis so it just has a soothing affect.

These are the subtle things that didn't initially occur to me as being narcosis. With more experience in general and with more experience with much greater narcosis at deeper depths I've become much more attuned to it at all depths. I realize it for what it is.

It doesn't affect me any more or less than it ever did but I am much more aware of it.

 

[Rhone Man]

I don't have as much experience at going deep as many others on the board, but I was always told (and have generally found to be true) that narcosis tends to come in the following in increasing stages:

• happy narc, euphoria
• paranoid narc
• tunnel vision narc
• hallucogenic narc

You are usually aware of the narcosis long before hallucinations kick in (only happened to me once, and it scared the bejesus out of me). It sounds improbably to me that you could be hallucinating at all at 98 feet, much less without experiencing prior symptoms.

Related: a lot of people subscribe to the "I didn't feel narc'ed at..." philosophy and this is of course true (that they didn't feel it). I was diving recently in Europe and the corrosive effects of narcosis on mental processes was brought home to me. Everyone else had SPGs denominated in bar, but mine was in PSI. No problem, I said - the maths is easy, I can do it in my head in a few seconds and I'll just convert. Well, on the boat it is really simple. At 125', it is suddenly a much more difficult piece of mental arithmetic...

 

[Satyre]

Actually, it's a rule.

You can't do the deep dive as the first dive of the *course*. You can, however, do the deep dive as the first dive of the *day* if you're conscientious and don't try to prop it in on day-1.

R..

As nobody has pointed this one out....

This is not a rule anymore. PADI sets that as a rule and soon after review it and it has been again allowed.
Have your instructor checking the Standards Update or get a newer version of the instructor manual.

Cheers