Deep Air Diving - thoughts

[DA Aquamaster]

It fits here about as well as anywhere else in the tech section and i assume the OP is wreck diver inclined and pentration of a wreck is not required ona wreck dive.

The OP may well get a different response from a cave diver where penetration is by definition going to occur, so I'm willing to assume the Op knows what he is doing and is targeting the audience he wants to target. If he requests it be moved to the general tech section, I am confident any of the mods will be happy to accomodate the request.

 

[texdiveguy]

It fits here about as well as anywhere else in the tech section and i assume the OP is wreck diver inclined and pentration of a wreck is not required.

You may well get a different response from a cave diver where penetration is by definition going to occur.

I casually know this diver and once even dove with him.....but all aside it probably would get better response from others if it were in the 'General' threads section of this Tech Diving sub-forum.

Deep air diving can be done in many location outside of wrecks and caves....such as o/w with a soft overhead.

Good thread....just for the OP's sake I think it would get more looks and input not being in the Wreck section.

 

[sheck33]

One of the most chilling diving stories I've heard to date was from my Fundies instructor. He told a story of doing a dive to what I remember as being about 110 feet, on air, in Croatia, where mix was not available. He had some kind of post failure at depth, after just a couple of minutes of diving. He shut the post, purged and rechecked, and bubbles continued, so they called the dive. They did a half depth stop, and at that stop, he rechecked his valves, and the one he thought he had closed was OPEN.

This is a guy who teaches valve drills and demonstrates them constantly; one would think that a valve shutdown sequence would be truly "do in your sleep" stuff for him. Yet he screwed it up at 110 feet, and the only explanation he has (or I have) was narcosis.

It's an anecdote, not a series, but it really hit me hard. If somebody with that much experience and very current training can make that stupid a mistake at depth, better I should be very cautious.

Yup, Steve told us the same story during my Fundies class last weekend. That story stuck. Deep air is like playing russian roulette.

I have a fairly recent example of my own. An instructor, 2 divers and me. Dive to 100 feet. I was basically just observing because I wanted to get in the water. The instructor and me were diving trimix (30/30 for me), the students were using air. For some obscure reason they were supposed to do some short version of a valve drill at that depth. One of the students had a hard time reaching valves and was exerting himself, the depth and the CO2 buildup were too much and he had to just sit on the bottom to come to his senses. He was narced out of his mind at just 100ft. Anyone saying they can 'handle' airdives to 200ft is just deluding him/herself.

 

[Bismark]

You can search for threads on this topic and find a plethora of examples. Most people have very strong opinions on the matter and most will not change those views. On an issue such as this, internet diving is not your best friend. Meet people face to face who have the experience and talk to them. You are dealing with matters that may well be life and death issues and I wouldn't take that kind of advice from someone who I couldn't talk to face to face. Like I said, we all have our opinions about deep air. Evaluate the quality and veracity of your information sources before you make your choice. Just my 2 cents.

 

[Thalassamania]

I've done a significant amount of work, on air, between 150 and 190 feet. That said, I should stress that I don't often dive in that range for fun or recreation. I am lucky that I don't often get particularly narced, when I feel that I am not doing well I immediately scrub the dive.

In my experience there are three keys to making deep air dives, the first is practice. I get in the pool or in shallow water and I perform the task that I will be doing over and over and over again. I do it with gloves on, I do it with my eyes closed, I do it with exactly the gear I will be using for the real thing, and then I do it again. The second is recognition that yesterday's immunity to narcosis may not mean jack today. The third is previsualization of the dive and the task. You need to take some quiet time on the deck, close your eyes and make the entire dive in your mind's eye. You need to imagine the things that can (and will) go wrong and think your way thought them, then rewind and pick up the dive where you left off.

 

[sheck33]

I've done a significant amount of work, on air, between 150 and 190 feet. That said, I should stress that I don't often dive in that range for fun or recreation. I am lucky that I don't often get particularly narced, when I feel that I am not doing well I immediately scrub the dive.

In my experience there are three keys to making deep air dives, the first is practice. I get in the pool or in shallow water and I perform the task that I will be doing over and over and over again. I do it with gloves on, I do it with my eyes closed, I do it with exactly the gear I will be using for the real thing, and then I do it again. The second is recognition that yesterday's immunity to narcosis may not mean jack today. The third is previsualization of the dive and the task. You need to take some quiet time on the deck, close your eyes and make the entire dive in your mind's eye. You need to imagine the things that can (and will) go wrong and think your way thought them, then rewind and pick up the dive where you left off.

You can do a task well, while affected by narcosis, by rehearsing it 100 times, yes.
The problem arises when you have to do something that is NOT rehearsed and unexpected.

Bold: you are never immune to narcosis. It is a physiological mechanism you have no control over. I assume you didnt mean literally immune?

 

[peterbj7]

Here in warm water I don't regard a dive as deep unless it's below say 150'. I routinely do air dives to those sorts of depths and often deeper. If I'm with other divers I don't know then it's another matter, and anywhere below about 100' I'm extremely diligent to observe them and be ready to act if necessary. But when I'm just playing I often go down to around 180'. I rarely go deeper, because here the higher level interest stops around there and the deeper interest doesn't start for another 50' feet or so, by which time I'm certainly on mix.

The deepest I've ever dived on air was a three day liveaboard trip to Tiran, in the Egyptian Red Sea. There I and another diver did 7 dives each day of the three, with the first 4 dives of each day being to around 75 mtr - that's about 250'. The reason being that there was something there we wanted to look at. I was deeply narced on the first of those 12 dives and on one other, but felt absolutely fine on the rest. Yes, I know it was foolish (pO2 almost 1.8) but hey, we got away with it, and 1.8 is still well within limits for navy divers.

In cold water it's quite another matter, and I've been significantly narced at 150'. Makes me wonder how people dive Dorothea Quarry in Wales, which is 109 mfw deep (almost 360 feet) and bitterly cold (it's snow melt-water) yet some people routinely dive to the bottom on air.

 

[sheck33]

Here in warm water I don't regard a dive as deep unless it's below say 150'. I routinely do air dives to those sorts of depths and often deeper. If I'm with other divers I don't know then it's another matter, and anywhere below about 100' I'm extremely diligent to observe them and be ready to act if necessary. But when I'm just playing I often go down to around 180'. I rarely go deeper, because here the higher level interest stops around there and the deeper interest doesn't start for another 50' feet or so, by which time I'm certainly on mix.

The deepest I've ever dived on air was a three day liveaboard trip to Tiran, in the Egyptian Red Sea. There I and another diver did 7 dives each day of the three, with the first 4 dives of each day being to around 75 mtr - that's about 250'. The reason being that there was something there we wanted to look at. I was deeply narced on the first of those 12 dives and on one other, but felt absolutely fine on the rest. Yes, I know it was foolish (pO2 almost 1.8) but hey, we got away with it, and 1.8 is still well within limits for navy divers.

In cold water it's quite another matter, and I've been significantly narced at 150'. Makes me wonder how people dive Dorothea Quarry in Wales, which is 109 mfw deep (almost 360 feet) and bitterly cold (it's snow melt-water) yet some people routinely dive to the bottom on air.

Well, you get away with it until you don't right?

 

[texdiveguy]

Under the optm. conditions doing moderate deep air diving while maintaining accepted protocols is fine for many experienced divers....it's been going on for years with a good success record. I have done a bit myself with favorable results. But being trimix trained I do prefer to use He in my deep mix now!

 

[dab]

After I had deep air training, I did several dives between 150' and 180' in the great lakes and did not really feel all that affected by narcosis (my perception). Then I obtained trimix training and for several years did no deep air other than a couple of trips to truk and bikini. The first time I did a 160' dive on air back in the great lakes I definately noticed the narcosis. The standard of comparision was there now and I won't do anything below 120 or so without some helium in the mix.