Equivalent Air Depth question

[Celt]

Absolutely agree 1000%, the key words being "learn to manage".

That is not to say I recommend deep air diving. Certainly I preferred to dive, and would recommend, a helium mix, as there can be some circumstances where the narcosis factor could become the difference between life and death, especially if diving in 'adverse conditions' as some folks, even very experienced folks, unfortunately found out the very hard way.

After all, as Dirty Harry said, "A mans gotta know his limitations".

You can learn to handle narcosis without a doubt but like you say for people with helium available to them and the ability to pay, why not avoid narcosis completely and be able to make deep dives at will.

 

[Wibble]

Just posing a question….
Is diving whilst under the influence of narcosis similar to driving under the influence of alcohol?

Go back decades and it was common to "have one for the road". Go back decades and it was common to dive with deep air and high PPO2

 

[Celt]

Just posing a question….
Is diving whilst under the influence of narcosis similar to driving under the influence of alcohol?

Go back decades and it was common to "have one for the road". Go back decades and it was common to dive with deep air and high PPO2

That’s just talk, no one in there right mind would plan a deep dive on air like a trip to the pub. Planing was meticulous and discipline was critical. No way would you lose track of your time or gas like you’d read about on some rec dives today. A lot more planning went into diving in the past, and I still do it to this day. To give an example I’m heading off in an hour to check the buoyancy of my aquazepp as I’ve replaced the batteries but I wouldn’t chance diving it without a check. Everything that was done deep was first done shallow and practiced.

 

[Akimbo]

Absolutely agree 1000%, the key words being "learn to manage".

Somebody better tell thousands of US Navy First Class Divers that they wasted a few weeks of school because that was most of what we were learning. Do you think that the submarine F-4 was salvaged from 306'/93M in 1915 by divers on air that were superhuman or just well trained and experienced?

Of course they were narced and less efficient than todays saturation divers on Helium-Oxygen, but they got 340 tons of submarine back to the surface without loosing any divers.

 

[Bob DBF]

Is diving whilst under the influence of narcosis similar to driving under the influence of alcohol?

No. Narcosis goes unnoticed, as one is not having a pint on the bar before it occurs, and one will not feel any effects until something happens and one has to think. It goes unnoticed in recreational diving all the time.

Go back decades and it was common to "have one for the road". Go back decades and it was common to dive with deep air and high PPO2

Back decades ago, there was no choice in gasses so dealing with narcosis and high PPO2 was just a fact. It wasn't deciding to have one for the road, it was just the way of the road.

Back in the day, I was trained to dive deco, and narcosis management was just part of the training. I have always been a recreational Diver, although I have been paid on occasion, and any training I received back then was by a mentor rather than by the couple of agencies of the day. Those agencies only trained OW at the time.

 

[Kay Dee]

Absolutely agree 1000%, the key words being "learn to manage".

Somebody better tell thousands of US Navy First Class Divers that they wasted a few weeks of school because that was most of what we were learning. Do you think that the submarine F-4 was salvaged from 306'/93M in 1915 by divers on air that were superhuman or just well trained and experienced?

Of course they were narced and less efficient than todays saturation divers on Helium-Oxygen, but they got 340 tons of submarine back to the surface without loosing any divers.

Well Akimbo, I am not at all sure how to respond to your above post. I have to ask, is the first sentence and then the follow up question of yours simply rhetorical, or are you being sarcastic (which of course is fine with me), or is it actually posed for me to respond to / answer as it were? If posed to me then all I can say is that you seemed to have missed the intent of my post, and specifically the one liner of mine you quote, by a country mile, or actually by a few miles it seems. If not posed to me, then I obviously missed the intent of your post.

I mean surely you did not think that one line you quote of mine was aimed at you, or your navy / commercial mates that used to work deep on air? So I gotta ask, what part of "Absolutely agree 1000%, the key words being 'learn to manage'" did you not understand? After all I was agreeing with you 1000%, and agreeing with you that divers need to 'learn to manage narcosis', which you yourself stated could be done in your previous post.

So I gotta say, I am completely at a loss as to the the intent of your first sentence and why you state such as a response to the one liner of mine you 'seem' to be responding to, where I am agreeing with you.

As for the question, although I (and the navy) and any sane person consider 90 odd metres / 300 odd feet (very) extreme on air, why would I think that thousands of US Navy First Class Divers wasted their time learning to manage narcosis situations (as I am agreeing with you that it can be done)?

So Akimbo, if you think my post was a slur aimed at you, your swabbie mates or commercial diver pals that used to dive deep on air for work (or play), it was certainly not.

However, as to "A mans gotta know his limitations" I stand by that. And that limitation for me on a 'working dive' as it were was pretty much 65/66m on air (and not because of narcosis, but the 1.6 clock, given the deco still to come) with the occasional dip in my profile to 70m or so if need be, but beyond that I thought it prudent not to go (and I am not talking about in caves, but on wrecks). And again, to others reading this who also may misinterpret my intent, for the record I AM NOT RECOMMENDING DEEP AIR DIVING to anyone, especially in this day and age. But at times in the past “a man had to do what a man had to do”, and over the years I often found myself in that situation in various parts of the world - sometime for weeks at a time of deep diving - where helium simply was not available, so we learnt to adapt to the situation at hand. Not by choice, but by necessity.

 

[Kay Dee]

Just posing a question….
Is diving whilst under the influence of narcosis similar to driving under the influence of alcohol?

Go back decades and it was common to "have one for the road". Go back decades and it was common to dive with deep air and high PPO2

May I ask, is your question simply rhetorical or meant to be answered? If meant to be answered of course it is not (even remotely) similar as others have stated.

Now a question (well three) for you, given your question in the above, and that I hope is not too personal and if so feel no obligation to answer whatsoever.

How long have you been diving, have you done any deep air diving in your career, and who (what name) was the last agency you took a dive course, any dive course, with?

 

[Wibble]

May I ask, is your question simply rhetorical or meant to be answered? If meant to be answered of course it is not (even remotely) similar as others have stated.

Now a question (well three) for you, given your question in the above, and that I hope is not too personal and if so feel no obligation to answer whatsoever.

How long have you been diving, have you done any deep air diving in your career, and who (what name) was the last agency you took a dive course, any course, with?

It was supposed to be thought provoking and metaphorical. Obviously wasn't what you inferred.

My experience with narcosis is very much like being in a pub after a few pints. Some of the effects are slightly different, but the general point stands. I've been completely fixated on checking depth and gas and would have missed a team of synchronised mermaids performing in front of me.

As a result, I choose to not go through that as, just like driving a car under the influence, it's fundamentally dangerous especially around wrecks. Driving nowadays is simply no alcohol. Diving below 40ish metres / 130ish feet is pretty much the same; add some helium to dial the narc down. When on a rebreather it's helium in the mix from 25m/80ft down and rich helium below 45m/150ft.

Diving on deep air is something that might have to be done -- remote locations, lack of helium, specific task, emergency, etc. It's not something that should be done, especially in this age of rebreathers -- it's not the seventies. And certainly not if you want to remember the dive -- we dive recreationally for fun and often at great expense (e.g. Truk); narcosis certainly affects my memory. When ferreting around in a wreck I absolutely don't want to do that off my face when there's the rebreather option waiting to be used.


Courses. Yeah, i dun my paddy a while ago whilst kneeling to the instructor demigod.

 

[johndiver999]

That is completely consistent with the experience I was attempting to describe.



That is inconsistent with my experience and observations of people I have worked with. That said, this group tends to be self-limiting. Divers who are uncomfortable on deep air don't accept deep air jobs and those that perform poorly don't get called for those jobs. To a considerable degree, the same sort of thing happens with recreational divers.

I agree, there is a good bit of self selection. I have known at least one very competent commercial scuba diver who said he hated to go below about 130 feet because he really did not feel comfortable with the narcosis. He did thousands of solo, working dives slightly past 100 feet.

I have known quite a few other scuba divers who appear to function reasonably well in 180 feet of water on air.

Acclimation, experience and confidence built upon familiarity with the particular environment seem to be factors as well.

 

[Dwmathews88]

Okay so I have a question. I’m currently working towards my ADCI card. (commercial diver card). On the commercial side we use Bimix so HeO2. Why on the TECH or REC side do we use TRIMIX? Wouldn’t it be easier and actually safer to take nitrogen out of the picture? I understand by using Archimedes principle we can find out the mixture we need. So a 80/20 or 79/21 mix would work great up to around 4ata off of the top of my head then we just reduce the O2 in the mix for greater depth. Of course with deco past probably 180 we would do a 50/50 nitrogen/O2 deco stop for a minute. Anyway all of my top of the head math aside…why does tech/rec use Trimix instead of bimix?