Deep Air Diving - thoughts

[Daylonious]

Correct - I'm interested currently in deep air wreck dives - 150-180 and I'll be operating a camera (DSLR rig) no penetration - and this will be carribbean with hopefully good viz, low currents and no obvious entanglement hazards.

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.

 

[Daylonious]

SOO, in summation of these posts concerning deep air dives:

1) you do not build a tolerance with successive dives

2) pre-visualization and familiarity with skills / equipment BEFORE the dive can really help

3) some days are worse than others narc wise

4) use trimix you idiot


That pretty much sum it up?

D>

 

[texdiveguy]

SOO, in summation of these posts concerning deep air dives:

1) you do not build a tolerance with successive dives

2) pre-visualization and familiarity with skills / equipment BEFORE the dive can really help

3) some days are worse than others narc wise

4) use trimix you idiot


That pretty much sum it up?

D>

****4) use trimix you aspiring deep diver.

 

[blatter]

Maybe I would add working up to deeper dives - especially after a break from diving, or break from deeper diving.

Anyway, working up to deeper depths does seem to help my own performance handling cameras on air dives deeper than 140 ft. I guess for me I routinely do air dives between 110 to 140 ft and often in tidal currents and less than ideal viz. If mistakes / incidents over many many hundreds of such dives are any indication, narcosis has not been a problem - so far.

As someone who has done thousands of dive I also have to say that experience doesn't hurt. in my opinion this is not so much in the sense of becoming "acclimatised" to narcosis as by building muscle memory and developing diving related procedures / skills so that they require less higher level mental agility to perform.

Having said that, I'm certain (as said by previous post) that there is considerable variation in the way people react to narcosis between individuals and in individuals between dives.

Whether a diver realizes it or not narcosis is having an effect - I vaguely remember reading a study that identified significant impacts on performance from around 50 ft in a dry chamber. When I used to work on deep diver courses in the 1980s (not very deep compared to technical dive courses of to today) it always seemed to be those that told me that they never got narcosis that did worst on objective skills tests and in only moderately deep water - say 120 - 140 ft.

I think one of the biggest dangers of narcosis is fixation on one aspect of the dive and forgetting to perform some vital task - eg monitoring depth but forgetting to check air or taking photos and forgetting about bottom time etc.

 

[DA Aquamaster]

1) you do not build a tolerance with successive dives

You don't build up tolerance, but there is an improved effect on performanc from work up dives. It is probably based on recency of experience and skills, familiarity under similar conditions, etc, but the effect is there.

One thing that has not yet been discussed is the psychology involved. There was a very interesting experiement where new divers with no prior knowledge of narcosis were divided into two groups. One group was trained to expect severe dibilitating effects from narcosis and the other was taught that narcosis was no big dela that a diver could adapt to and deal with.

All of the divers in the "debilitating effect" groups reported severe impairment from narcosis on the same dives and and demonstrated markedly poorer performance on the same tasks as the "narcosis is no big deal" who with only one or two exceptions perfomed significantly better and reported minimal impairmement. This effect also occurred in the "debilitating effect" group at shallow depths where narcosis is not normally a significant issue but where the divers were told and thought they were at a deeper depth.

So...the experment suggests that your expectations regarding deep air will have a significant impact on the effects of narcosis you actually experience. In other words a diver who took a deep air course from Hal Watts, may have an entirely different expectation of perfromance on a deep air dive and in fact perform better than a diver trained to use trimix on any dive with an END greater than 70 to 100 ft due to the severe impairment the "deep air is bad" diver expects from narcosis.

It could be that the trimix indoctrinated diver feels it is futile to resist narcosis so they don't. In other cass perhaps they feel liberated in a sense to make mistakes that are then attributed to narcosis that they would not have made otherwise. In some cases it may just be that it can be cool or exciting to experience an effect you expect to the point that it occurs when it really doesn't. In many cases I suspect divers anticipate narcosis, become overly anxious about the hit on performance and the diversion of assets to worrying about it or being on guard against it reduce the resources they have to work the problem and in effect bring about a self fullfilling prophecy. All invovle to some degree an element of suggestibility which varies from diver to diver - just like the effects and utility of hypnosis. It would be interesting to measure an individual divers suceptibility to hypnosis and to see if that level of suggestibility correlates with their impairment to the effects of narcosis. (before anyone brings out the flame thrower, I am talking about correlation not causality - please understand the difference.)

In any event I suspect this facet of narocosis may explain why on one hand most deep air divers feel work up dives help, while most research indicates it does not - you'd have to do a double blind study into both effects simultaneously to control for the confounding effects the differing demand characteristics underlying both studies would have on their respective outcomes.

 

[VooDooGasMan]

Hey , Day

1 you can build a tolerance

2 Diving all the time is your familarity

3 low vis, first time at dive site, little sleep, etc

4 Trimix is a proven way to adjust the narcosis to your comfort.


To do deep air diving, have plenty of air, take a 75% pony to reduce deco.

Keep doin the max of your comfort, eventually you'll feel like it is nothing.


The post on the instructor with trimix, student on air, is just that they took them to a uncomfortable depth.

Diving on deep air is still done all the time, there is less gear task loading, computers for deco makes it even easier.

My experience is congestion is a damper on my dive depth, so that stops me from reaching my max comfy level, My wife has no narcotic affect, she laughs on thing I do at depth.

My therory is only from statics of are diving, A 200' dive on double 104 hp's packed to the gill on air, she surfaces with 1200 more psi than me. Obviously she is taken in less nitrogen therefore less narc'ed.

When I'm narced I control it cause I love it, monitor your gauges so not to run into trouble.

You can learn about trimix on the net to determine if your ready to go for a more extensive route of diving.

Diving has a life long of learning steps so not to become bored, the lost interest is due to $$$$,
Trimix, rebreater, Travel, Charter, So you have your own choice where you want to take it.


I just got Back from an Early mornig wall dive at slack, Good Narc.


Happy Diving

 

[Trimix2dive]

I only read the first few post. Why? Would you enjoy a possible watery grave, or do you want to do it safely with mixed gas?

I guess if you want to chance the law of physics your welcome to it. But you know why they don't send donkeys to college.

 

[wedivebc]

You don't build up tolerance, but there is an improved effect on performanc from work up dives. It is probably based on recency of experience and skills, familiarity under similar conditions, etc, but the effect is there.

I agree with that hypothesis but let me add that divers who are comfortable in a particular environment tend to breath more effectively underwater. That makes them less likely to retain CO2 which is suspected to exacerbate the effects of nitrogen narcosis. I believe there are probably other mechanisms at play as well that allow divers to tolerate narcosis.

 

[wedivebc]

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.

I disagree, yes there are some strong opinions on the subject which is all the more reason to discuss them in a public forum where thousands of B-S meters all operating concurrently are more likely to get to the truth than one individual with a strongly held opinion and an agenda.

 

[Bismark]

I disagree, yes there are some strong opinions on the subject which is all the more reason to discuss them in a public forum where thousands of B-S meters all operating concurrently are more likely to get to the truth than one individual with a strongly held opinion and an agenda.

In the academic world, before an article appears in a scholarly journal, it is first vetted by several academics in the field of good standing. This does not happen on SB. In this case, anybody with a computer can post as an "expert" and somewhere, somebody will take that person's advice to heart. There are tons of questions posted on this board that are answered by people with very little diving experience. Moreover, the bigger issue is that there is no way of knowing even whether you or I can actually "walk the walk" or are just "talking the talk". You are entitled to your view but mine is that it is next to ludicrous to take advice that can affect your survival in this type of circumstance. For items of next to little importance I might solicit opinions but for matters of potential life and death I will not trust the internet. I will instead meet people face to face and establish the bona fides before I take their advice. Just my 2 cents.