Scuba diver dies after being found floating at Kurnell, NSW, Australia

[DevonDiver]

I'd imagine that making even just one somewhat poor decision due to stress (as opposed to being utterly incapable of any logical problem-solving due to panic) could be enough for a terrible outcome.

Accidents tend to comprise of a "chain" of errors, leading to that "terrible outcome". The length of that 'chain' is really determined by how forgiving the specific dive is. Recreational diving tends to be very 'forgiving'. More extreme, technical or overhead environments are increasingly less 'forgiving'.

The 'accident chain' often starts long before the diver enters the water. It could start with their mindset, attitude, knowledge, health, underlying stressors etc. It continues with pre-dive planning, buddy checks, adherence to agree or standardized protocols on the dive itself. Equipment issues form varied links in that chain; maintenance, servicing, appropriateness for the dive, diver familiarity etc. Lastly, diver competency and experience with emergency procedures and responses.

The final stage of acute panic response really just illustrates an overwhelming and abrupt end to the chain. It is not the time to break the sequence.

My article: Scuba Diving Stress Management and Acute Panic Response

In most, if not all, incidents breaking any of those links is sufficient to end the chain of events leading to a catastrophic incident. Especially so on recreational dives. Even more so on very benign dives, such as the one which claimed Marcia.

So, no, I disagree that "one somewhat poor decision" can be enough. In truth, a lot of very poor decisions need to occur for a terrible outcome.

 

[xyrandomyx]

Accidents tend to comprise of a "chain" of errors, leading to that "terrible outcome". The length of that 'chain' is really determined by how forgiving the specific dive is. Recreational diving tends to be very 'forgiving'. More extreme, technical or overhead environments are increasingly less 'forgiving'.

The 'accident chain' often starts long before the diver enters the water. It could start with their mindset, attitude, knowledge, health, underlying stressors etc. It continues with pre-dive planning, buddy checks, adherence to agree or standardized protocols on the dive itself. Equipment issues form varied links in that chain; maintenance, servicing, appropriateness for the dive, diver familiarity etc. Lastly, diver competency and experience with emergency procedures and responses.

The final stage of acute panic response really just illustrates an overwhelming and abrupt end to the chain. It is not the time to break the sequence.

My article: Scuba Diving Stress Management and Acute Panic Response

In most, if not all, incidents breaking any of those links is sufficient to end the chain of events leading to a catastrophic incident. Especially so on recreational dives. Even more so on very benign dives, such as the one which claimed Marcia.

So, no, I disagree that "one somewhat poor decision" can be enough. In truth, a lot of very poor decisions need to occur for a terrible outcome.

I did specifically say 'In a critical situation, like being out of gas without a buddy or redundant source, I'd imagine that making even just one somewhat poor decision...' I realise that it takes a number of prior poor decisions to reach that point.

 

[nm7sp]

"The latest regulator technology delivers gas down to a very low pressure without an obvious drop in performance"

I'm interested in your comparison between "old" regs and current hi performance regs.

If I'm running *really* low on gas. I would like to know right away, not just when I have 0 - 3 breaths left.
And what we are saying is that if you are task overloaded or panicked then you've maybe only have zero breaths left when you are finally forced to face
the stark reality that you've run the gas a little bit too far.

I would prefer a much safer system of... lets have a "reserve tank"

It's not an optional "pony", it's an obligatory built-in "reserve tank" - just like on an (old) car.
When (if) you go OOA (which would be about 20 breaths earlier under my system) you just hit the big (red???) panic button and suddenly you have a couple of options again. (I.E - 20 - breaths)
Obviously you have to be able to push this button with either hand, or maybe just with you head. It has to be idiot proof since if panicked or OOA you are likely to respond in such a manner.

PS - not sure how this relates to other gas mixtures or whether it even needs to?? - probably only really usefully at shallow depths.

 

[Diver0001]

I'm interested in your comparison between "old" regs and current hi performance regs.

This discussion is getting pretty far removed from Quero's accident now but I'd like to respond to this because I have actually done a test like this. I won't bother with all of the details but the difference in how much warning you get between older regs (I used an unbalanced piston from 1972) and a modern high-performance reg is huge.

Basically my conclusion is that with an older reg, especially an unbalanced one, you get some warning as stiffness really starts to become noticeable with a bit over 10 bar left in the tank. A high-performance reg, however will give you *maybe* 2 or 3 breaths.... or in other words, about what you get with the pressure in the hoses. In the test I did the tank pressure when empty using a high-performance reg was so low that I could open up the valve and blow air back into the tank with my mouth.

In other words, there *is* virtually no warning and all this stuff about stiffness doesn't apply (in my experience) to modern regulators. Your only protection from that is to monitor your air pressure.

It's not an optional "pony", it's an obligatory built-in "reserve tank" - just like on an (old) car.

Before the advent of the spg tanks did have a "reserve" mode. It was a feature of the tank valve called a "J-valve". One manufacturer (I believe it may have been Dacor) also built a J-valve into one of their regulators.

If you ask me, a "reserve" mode doesn't make any sense. You need to monitor your instruments. That's the only thing that makes sense. For a reserve some divers also use a totally separate "pony" or "stage" tank but that's more for "bail-out" in case of a regulator malfunction than any part of the gas plan.

PS - not sure how this relates to other gas mixtures or whether it even needs to?? - probably only really usefully at shallow depths.

The only thing that's really useful is to monitor your gas supply and never get in that situation. Going OOA is probably the trigger for about 50% of accidents and it's the *one* thing that is completely avoidable.

R..

 

[nm7sp]

"You need to monitor your instruments"

Ok -I agree with all you've said but if your instruments are giving a false readings, then you need to have greater margins of safety. This is the first (sorry --- second) lesson I take from this - gadgets MUST work properly but do not EVER rely on them completely - like you - they can break.

 

[Diver0001]

Yes, of course. We're taught to keep reserves for, among other things, this very reason.

R..

 

[MXGratefulDiver]

"You need to monitor your instruments"

Ok -I agree with all you've said but if your instruments are giving a false readings, then you need to have greater margins of safety. This is the first (sorry --- second) lesson I take from this - gadgets MUST work properly but do not EVER rely on them completely - like you - they can break.

We already have that ... it's called gas reserves, and it's something you're supposed to learn about in your basic scuba training.

If the gauge is off by 150 psi and you run out of air, then the simple conclusion is that you're cutting your reserves too thin ... way past what your training says you should be doing ...

... Bob (Grateful Diver)

 

[gypsyjim]

"The latest regulator technology delivers gas down to a very low pressure without an obvious drop in performance"

I'm interested in your comparison between "old" regs and current hi performance regs.

If I'm running *really* low on gas. I would like to know right away, not just when I have 0 - 3 breaths left.
And what we are saying is that if you are task overloaded or panicked then you've maybe only have zero breaths left when you are finally forced to face
the stark reality that you've run the gas a little bit too far.

I would prefer a much safer system of... lets have a "reserve tank"

It's not an optional "pony", it's an obligatory built-in "reserve tank" - just like on an (old) car.
When (if) you go OOA (which would be about 20 breaths earlier under my system) you just hit the big (red???) panic button and suddenly you have a couple of options again. (I.E - 20 - breaths)
Obviously you have to be able to push this button with either hand, or maybe just with you head. It has to be idiot proof since if panicked or OOA you are likely to respond in such a manner.

PS - not sure how this relates to other gas mixtures or whether it even needs to?? - probably only really usefully at shallow depths.

When I first began diving we would breath down our gas till it started to get a bit harder to draw a breath, and then we had a couple of breaths before we had to "flip" the J valve for our reserve.

A few years later someone came up with a novel invention that made things much safer, called a submersible pressure gauge, or SPG in today's terminology. By keeping track of your gas useage and pressure at all times while under the water it suddenly became possible to avoid the OOA thing completely, barring a significant failure of your system

This discussion is getting pretty far removed from Quero's accident now but I'd like to respond to this because I have actually done a test like this. I won't bother with all of the details but the difference in how much warning you get between older regs (I used an unbalanced piston from 1972) and a modern high-performance reg is huge.

Basically my conclusion is that with an older reg, especially an unbalanced one, you get some warning as stiffness really starts to become noticeable with a bit over 10 bar left in the tank. A high-performance reg, however will give you *maybe* 2 or 3 breaths.... or in other words, about what you get with the pressure in the hoses. In the test I did the tank pressure when empty using a high-performance reg was so low that I could open up the valve and blow air back into the tank with my mouth.

In other words, there *is* virtually no warning and all this stuff about stiffness doesn't apply (in my experience) to modern regulators. Your only protection from that is to monitor your air pressure.



Before the advent of the spg tanks did have a "reserve" mode. It was a feature of the tank valve called a "J-valve". One manufacturer (I believe it may have been Dacor) also built a J-valve into one of their regulators.

If you ask me, a "reserve" mode doesn't make any sense. You need to monitor your instruments. That's the only thing that makes sense. For a reserve some divers also use a totally separate "pony" or "stage" tank but that's more for "bail-out" in case of a regulator malfunction than any part of the gas plan.



The only thing that's really useful is to monitor your gas supply and never get in that situation. Going OOA is probably the trigger for about 50% of accidents and it's the *one* thing that is completely avoidable.

R..

A few years ago I had the occasion to breath a tank to E, while searching in @ 20 ft of water for a dropped camera, but it was no surprise when I did feel that "drag" on my regulator because I knew exactly what my SPG said the entire time I was searching.
Reading your post, it did seem to be nearly an instant loss of pressure too, compared to the old days and the now 'vintage gear' we were using, but I did not stop to think about that part as I made my ascent.

 

[MXGratefulDiver]

There's a reason J-valves fell out of favor ... it had less to do with the SPG than it did with how easy it was to misuse the J-valve and find yourself without any reserve at all.

Any piece of equipment is only as good as the willingness or ability of the user to use it correctly ...

... Bob (Grateful Diver)

 

[scubadada]

In my short membership to scubaboard, I have never seen a post in accidents and incidents about someone who lived because of ditching weights. I am always reading the forum and danydon makes a good job posting everything.

So I guess there's something missing we are humans and no stupids, I think if you are in trouble and in a close call you will ditch them..

I didn't know her but she was OLD around 60?
Must of the post I see here they are always old people who die.

Don't you thing it was something medical hard to explain?

buton, you've mada an error here, take care who you call old. I'll give you the benefit of the doubt, perhaps just the ignorance of youth