The deep air angle - split from Missouri Fatality

[Cave Diver]

Perhaps this is best discussed in the commercial diving area. I have already stated that in my opinion, a diver's equipment has nothing to do with the diver's ability to dive safely from a narcosis perspective. The diver can either function in a safe manner and perform his job properly, or he can't. The workplace health and safety regulations governing the safety of the diver are clear. If there is a safety hazard, the dive must be terminated.

Yet, OSHA states additional safety measures that must be taken into account for diving below 100' on air. Specifically:

• Subpart Title: Commercial Diving Operations
• Standard Number: 1910.425
• Title: Surface-supplied air diving.

1910.425(c)(4)

For dives deeper than 100 fsw or outside the no-decompression limits:

1910.425(c)(4)(i)

A separate dive team member shall tend each diver in the water;

1910.425(c)(4)(ii)

A standby diver shall be available while a diver is in the water;

The fact that you want to take the discussion on requirements for commercial diving to the commercial forum reinforces the fact to me that comparing your dives as a commercial diver and these dives as recreational divers are apples and oranges.

 

[DCBC]

The fact that you want to take the discussion on requirements for commercial diving to the commercial forum reinforces the fact to me that comparing your dives as a commercial diver and these dives as recreational divers are apples and oranges.

They are not apples and oranges. PM sent.

 

[wedivebc]

I just want to know why nearly every accident that occurs from a dive greater than about 100ft has an END greater than 100ft. I'm pretty sure you know why, but you don't want to say it because it would negate your argument.

Because most people do not use helium when diving and lots of people go below 100ft without so it would stand that plenty of fatalities would have a END greater than 100ft. Deep diving in more dangerous. Show me any statistics that prove diving with helium is safer.

 

[Rhone Man]

Read through this thread, and like the previous 8 or so deep air threads it has proved unedifying. If I can try to summarise:

• reducing narcosis through helium will usually make a dive safer
• if helium was cheap and widely available, likely everyone would use it on deep dives
• however, helium is neither cheap nor widely available
• accordingly different divers make decisions based upon their own assessments of risks and limitations in relation to diving without helium
• some divers think that the decisions that other divers make are foolish
• um, I think that is about it. Did I miss anything new?

 

[DaleC]

some divers think that the decisions that other divers make are foolish
[*]um, I think that is about it. Did I miss anything new?

[*] Some people think the risks they take are acceptable but the risks others take are foolish.


I just compiled a list of deaths during decompression dives and have come to a startling conclusion: It is more dangerous to use a manifolded doubles rig than a single cylinder on decompression dives.
I noted that, in most of the fatalities, the divers were using doubles and thus conclude that this was a contributing factor to their deaths. Some might consider this sort of corellation inconclusive but...

 

[Cave Diver]

I just compiled a list of deaths during decompression dives and have come to a startling conclusion: It is more dangerous to use a manifolded doubles rig than a single cylinder on decompression dives.

Sounds like the divemaster on my last Oriskany dive. We stopped in Pensacola on the way to go cave diving and were using our double cave rig for the Oriskany dives. The DM, who had never seen us before or didn't bother asking any of our experience gave us a 10 minute lecture on how unsafe our doubles were and that all they were good for was to provide just enough gas to get ourselves in trouble by violating NDL's.

Somehow we managed to keep our mouths shut and pretend to listen.

 

[Trace Malinowski]

Is air really a death gas or is air getting a bad reputation, statistically, because the divers who are most likely to go deep without the proper skill and training would be more likely to use air?

Obtaining air is something that an open water diver can do. I had a student make a solo 114 foot dive at night into low to zero vis in the Delaware River at Narrowsburg, NY with only 1 primary light and no line or float the day after he completed his open water course. His light failed. He called to thank me for saving his life telling me that I was a good instructor. I told him I must be a poor instructor because somewhere between, "This is a face mask. Look for tempered glass ... and ... here is your C-card," I must have forgotten to mention don't go solo diving to 114 feet at night in limited to zero vis with only one light. Had he died, this would have been recorded as another diver death on air deeper than 100 feet. The stupidity of the action given his experience and training would get lost in statistics.

Trimix isn't as easy to obtain. I wonder if those divers who seek trimix certification are naturally more inclined to be safer divers and less likely to do stupid cowboy stuff? They become better deep divers through training because they are smart enough to seek training. Trimix can help a smart diver stay smart at depth. Trimix can't help a diver who would be unsafe at any depth. However, that guy would most likely be weeded out by instructors or experience a change of attitude thanks to training.

Are we demonizing all deep air diving without the full story? I totally advocate trimix diving and believe the more we can reduce narcosis the better. But, I think that there may be more going on during deep air accidents than simply, "Deep + Air = Bad." Accidents are often a chain of events and the other links may have been put in place well before the tanks were filled.

Air and trimix both have their problems. I don't think air is a death gas any more than I believe trimix is our savior. They are both tools and need to be used properly, smartly and safely with their strengths and weaknesses well understood by their users.

 

[Scott L]

Read through this thread, and like the previous 8 or so deep air threads it has proved unedifying. If I can try to summarise:

• reducing narcosis through helium will usually make a dive safer
• if helium was cheap and widely available, likely everyone would use it on deep dives
• however, helium is neither cheap nor widely available
• accordingly different divers make decisions based upon their own assessments of risks and limitations in relation to diving without helium
• some divers think that the decisions that other divers make are foolish
• um, I think that is about it. Did I miss anything new?

Spot on IMO. These threads are just an attempt to aggrevate the GUE crowd. How anyone could argue with someone who has chosen a relatively lower END then they is beyond me. Similar to suggesting they have one more drink before hitting the road...

 

[DaleC]

Trace, this reminds me of something I was thinking about earlier today.

Is someone who dives close to (but within) the NDL's safer than someone who intentionally dives beyond the NDL's?
While it is a generalization, many people come close to decompression without considering the ramifications or having any sort of off gassing plan because they are still "safe" while those who intentionally go into deco usually consider the effects and plan to offgas accordingly. Somewhat similar to your thinking in the post above (which I agree with).
I was considering that decompression diving was not really any more dangerous than non decompression diving IF one could meet the deco obligation that results. It is in being able to meet the obligation that the danger lurks.

 

[dumpsterDiver]

I hope you're kidding.

The point of that is to show you that getting hurt on a deep dive is highly correlated with a high END. Will you automatically die at 101ft? No. However, the deeper you go (without helium) the closer to that razor's edge you get. Diving with low ENDs doesn't have the body count that high ENDs do.
I don't dive on air at all (unless its some 30ft reef dive), everything else gets 32% or gas. Period. Past ~110, you bet I'm on gas.

Plot, I see where you're going with this, and I see why you think its a little strange. Since day one, you've been told the air limit is 130ft, now you're hearing something different. This is normal. Unfortunately, diving deeper adds in some very serious issues (reserve gas, emergency procedures, ascent strategies, limited time at depth), and having a clear head is needed to adapt to any dynamic changes occurring at depth.

Plus, 179' is past the course limit :headscratch: for this dive. Something went wrong before they even got there.

This bolded comment implies a real lack of understanding of the situation. There is NO RAZORS EDGE! Instead there is a very wide depth range where diving air becomes increasingly more dangerous. Drawing the line at 100 ft is much. much too conservative for me, but if that what it says in the book that you follow...GREAT.!!!

I feel that for most of the conditions I dive in (open water, daytime, usually good visbility, relatively warm water) 200 feet is a better limit, but even then, I will infrequently exceed that on air, if there is something I want to see.