Exactly how deep is "Deep Air?"

[LiteHedded]

I agree. It seems that some people like to believe what they read; others believe what they have come to know through personal experience. It's funny that some "authorities" talk the talk without ever having walked the walk.

yea
pussies.

 

[grf88]

In his post TraceMalin refers to the Mount-Milner study. I saw it some time ago and thinking about it again it is possible that some people have been so preconditioned to the idea of narcosis at depths greater than 100 END that their own experience with narcosis at anything above those depths is so debilitating that they are scared for others that venture deeper. Maybe they should stop trying to scare people how dangerous it is, we might have fewer people seriously impaired by narcosis at moderate depths(100-150) on air. Outside of the US helium is not readily available in too many locations and where it is its cost can be prohibitive for the average diver.

Mount-Milner

 

[Blackwood]

here isn't a specific limit that anyone can point to and say would be right for everyone else. It's really going to boil down to the individual and the circumstances of the dive.

I think that was the point.

Like a lot of things involving diving ... the only valid answer is "it depends" ... which is why the most important skills any diver can develop are awareness and good judgment.
... Bob (Grateful Diver)

[/thread]

 

[UCFKnightDiver]

In his post TraceMalin refers to the Mount-Milner study. I saw it some time ago and thinking about it again it is possible that some people have been so preconditioned to the idea of narcosis at depths greater than 100 END that their own experience with narcosis at anything above those depths is so debilitating that they are scared for others that venture deeper. Maybe they should stop trying to scare people how dangerous it is, we might have fewer people seriously impaired by narcosis at moderate depths(100-150) on air. Outside of the US helium is not readily available in too many locations and where it is its cost can be prohibitive for the average diver.

Mount-Milner

I'm sure it can affect one's perception to actual narcosis, though it can go the other way as well with the 'macho' attitude some people have, people diving like this can perceive being less effected, when in reality they may be quite effected.

 

[grf88]

I'm sure it can affect one's perception to actual narcosis, though it can go the other way as well with the 'macho' attitude some people have, people diving like this can perceive being less effected, when in reality they may be quite effected.

The tests were not measuring the "perception" of narcosis but the actual impairment, or lack of, produced which varied considerably based on the preconditioning. This has nothing to do with 'macho' attitude.

 

[UCFKnightDiver]

I just read the study, I have a question; initialy they did the tests at 50fsw to provide a baseline, and then said they changed the tests. When doing the tests at different depths did they again change the tests? This could be simply learning to do the required tasks and have nothing to do with critical thinking.

 

[grf88]

I just read the study, I have a question; initialy they did the tests at 50fsw to provide a baseline, and then said they changed the tests. When doing the tests at different depths did they again change the tests? This could be simply learning to do the required tasks and have nothing to do with critical thinking.

Strange that those preconditioned were unable to learn at the same rate as those that were not preconditioned. I do not know how the tests were actually changed but the testers were obviously aware that doing things from memory could influence the study so probably took measures to avoid that.

 

[boulderjohn]

Just a few nit-picking items:

In 1977, Sheck Exley published Basic Cave Diving: A Blueprint for Survival in which he listed the known causes for the majority of cave diving accidents. According to Sheck the main reasons that divers died in caves was:

1) Failure to run a continuous guideline to open water
2) Failure to reserve at least 2/3 of the gas supply for exit
3) Diving deep in caves

"Deep" was defined as greater than 130 feet on air.

Here is what it says on page 13:

HOW DEEP IS TOO DEEP?
The sports diving community advocates limiting dives to 130 ft. or shallower and it would appear that there is a very good reason for it. An analysis by the author of cave diving accidents in Florida has shown that the small percentage of accidents where a continuous guideline and the "third rule" were used all involved dives to depths of 155 ft. or greater. Further, the shallowest depth at which "depth blackout" - the most likely cause of Barry and Luke's deaths - has been observed to occur at 150 ft.

Barry and Luke were two divers who were found dead at a depth of about 260 feet. Sheck blames "depth blackout"--passing out and continuing to breathe until all air is gone--as the reason for deaths on deep dives. He ascribes a lack of training for this, noting that in all cases in which people had recovered from "depth blackout," the dive on which it occurred was the deepest they had ever done. He also notes heavy exertion as being associated with it. Sheck does suggest 130 feet as a limit, but says that people can dive deeper if they train themselves through progressively deeper dives in open water. He suggests this training should be done under the guidance of divers who know how to dive deep.

By 1984, Wes Skiles added:

4) Failure to be trained or exceeding the limits of one's training
5) Failure to carry at least 3 lights

Exley's book covers the need to carry three lights in Chapter 5, pages 17-19.

 

[DaleC]

Sheck does suggest 130 feet as a limit, but says that people can dive deeper if they train themselves through progressively deeper dives in open water. He suggests this training should be done under the guidance of divers who know how to dive deep.

So glad dinosaurs like him aren't around anymore to promulgate such nonsense.
(tongue set firmly in cheek).

 

[LiteHedded]

So glad dinosaurs like him aren't around anymore to promulgate such nonsense.
(tongue set firmly in cheek).

well he is on the deep air death list...
just sayin'