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

[gypsyjim]

OK, if you have been following a lot of recent threads, you know that I may seem to me rabid in my obsession with proper weighting. Consequently, what follows will seem to be a contradiction.

A number of years ago I was very much dialed in to getting my total weighting perfect. I determined that if I were wearing the BCD I owned (ScubaPro Nighthawk) with a 3mm suit, I was perfectly weighted in salt water with 8 pounds of lead. I further determined that if I distributed that lead in 2 pound weights in the hip pockets and the shoulder pockets, I was also in perfect trim.

Around that time I started doing tech training in steel doubles, dry suit, and a steel back plate, I got used to being very much overweighted, and I got used to focusing on getting perfect trim. (For those of you who don't know, on a fairly basic tech dive, you might lose 15 pounds of air during the dive, so you must start the dive significantly overweighted.)

Then I went on a recreational diving trip to a warm water resort in my 3mm suit. I discovered that the boat I was on stocked nothing but 4 pound weights. That meant that if I wanted to go with my ideal 8 pounds of weight, I would have a serious distribution problem. I did not want to have it all on my hips, and I did not want to be lopsided. I thought it through for a long time and finally decided that as accustomed as I had become to being overwieghted through my tech training, I would try an even distribution of 4 pound weights among my 4 weight pickets. That means I would have a total of 16 pounds--8 pounds overweighted.

It was a great dive. I was in perfect trim throughout the dive, and I could control my buoyancy easily. I stayed with that weight configuration throughout the week.

I came to the conclusion that, at that point in my diving career, although weight and trim were both important, trim was for me more important. Of course, I had had a lot more experience than a lot of divers. I was used to diving overweighted. I am sure it would have been a real problem if I had done that earlier in my career.

Perhaps she was working on the same theory.

As read her posts, her being concerned about any possible over weighting was not mentioned, but her concern about trim was. She did mention that she could see why divers in dry suits often used jet style fins, to add weight to the feet as part of trimming the dry suit out. I do not know what her solution to that issue was though.

 

[DevonDiver]

Was she an accomplished freediver? If not, it is very unlikely that a normal person who has not practiced and subjected themselves to endless cycles of hypoxia and CO2 build-up is going to be "comfortable" pushing themselves close to a BO... Doing a lot of scuba diving is not equivalent to this type of training..

The ability to breathhold to the point of BO is often assoicated with (excess) hyperventilation which precedes the dive and artificially depresses the CO2 and consequently the urge to breath. And of course it is vastly more common on ascent.

This is something I couldn't comment upon from personal experience. Freedivers train to ignore the urge at leisure - but I think many people, especially experienced divers, could do it if their life was on the line. I've gone beyond the urge to breathe, but that was when skin-diving (with hyperventilation). I've gone as far as the 'gulps' when air-depleted on scuba - but stopped there (kinda what I mentioned in a previous post about pushing things too far and not feeling unduely scared... the "gulps" is where I get my alarm call finally... and that is pretty close to the end of it...)

I assume that if a diver keeps the regulator in, under air-depletion they would be sucking on that (getting nothing) until the point of black-out. It would be involuntary. In other circumstances, (regulator out) the diver would have inhaled water.

Having said that, I don't think the freediving training allows people to 'ignore the urge' through hyperventilation/CO2 depression - I thought they all go through that urge, but only practice of resisting the urge allowed them to pass beyond it. The hyperventilation just delayed that a little, nothing more.

Watching documentaries about miltiary diving training in the USA, there seems to be quite a few 'black-outs' during the harassment phases in the pool...

 

[Diving Dubai]

I've read the whole thread over the last 3 days and want to analyse the relevant facts (or Statements) that cause me confusion

1. Marcia was found in shallow water with a full BC. Everyone assumes this is where she passed away. Wrong. This is where she ended up. Since she was negative she would have sunk once hypoxia set in - this as I understand (and it has been mentioned before) can vary from person to person, but under stress can be fast.
2. The Buddies had a hard time swimming her remains to the surface. Please remember that it is possible while unconscious for the body to ingest water. Once the laryngospasm has ceased then water will enter the lungs in addition to the stomach thus the person may have an additional 6lbs or 3kg of extra weight from sea water.
3. In the Photographs posted - ignoring the differences between the bouyancy methods, Marcia seemed to be neutral at 12m, indeed she will have carried out safety stops prior to the incident? Surely if you are neutral at 12m (even with a full wing) then you are buoyant at below 6m? (Assumes no equipment malfunction). Even given that she was new to the equipment one must assume that Marcia would know when she was really too heavy? That said I believe those more familiar with Dry suites have give a plausible explanation with suit venting, given that it was reported that the suit did not flood.
4. There has been much debate over the Gas reserve, as I understand it (feel free to correct me) If you dive on PSI then the convention is that you come up with 500 (30bar) where as the metric system is that you surface with 50bar (725psi) - If Marcia dropped down on 50bar and swam off another 20bar (which at those depths should take a while) she would still come up with a safe margin.

These are the points which I've been going over and over. Roturer's synopsis on page 14 (post 131) still seems to be the most likely cause given - however my one concern is that with a full tank then on surface entry surely it would become apparent that you couldn't hold on the surface and that something must be wrong with the set up?

Given that all accidents are a combination of differing factors and removing just one of the factors makes the accident survivable I can't help wondering that there is a small piece of the jigsaw missing...

Caveat 1: I have experience in Air accident investigation so tend to mull over details more than most...

Personal comment:- This incident has made me completely re-evaluate all my diving practices - which as others have pointed out is the greatest legacy of this sad incident - RIP Marcia

 

[phoenix31tt]

Having said that, I don't think the freediving training allows people to 'ignore the urge' through hyperventilation/CO2 depression - I thought they all go through that urge, but only practice of resisting the urge allowed them to pass beyond it. The hyperventilation just delayed that a little, nothing more.

Maybe a true free diver could correct me if im wrong... The urge to breathe is caused by co2 build up.. Hyperventilation reduces co2 but does NOT increase O2... thus if done to far, you actually will not feel the urge to breathe before you blackout

So yes you can hyperventilate to the point where you do not resist the urge to breathe before you blackout... In that case I wouldn't say that they "go through the urge"







Sent from my Nokia Lumia 920

 

[gee13]

For all the possible hypotheses Im yet to read too much about the possibility of the camera being a liability in the sense of Marcia encountering a subject at the end of the dive and assuming that the amount of air at such shallow depth would have allowed her to get into ooa situation as she was busy photographing a critter? Perhaps a correlation between time of last shots and time of computer depth data may yield some answers. I myself had a dive early this year in familiar waters and been so focussed on taking shots of something toward the end of the dive in shallow waters knowing roughly that I had about 40-50 bar left, snapping away at 8m to realise that squeezing feel on the regulator and having lost all track of time checked my gauge to 10 bar. Instead of bolting to surface I was calm and decided to slowly ascend instead of shooting up to the surface.

I wonder if this calm rational (non panicked) state that I was in may have possibly resulted in a shallow water blackout due to PO2 levels or perhaps I may have simply run out of air totally at 4-5 m and drowned. Maybe bolting to surface with haste may have been safer even with risk of dci but at surface my chance of srvival is better...?

Panic survival mode? Or lack of ... leading to possibly complacency? Whats is better ...or worse?

All my gear was familiar, tropical wetsuit configuration that had hundreds of dives in. I got lucky this time and I live to tell this tale. Perhaps as Andy theorized in Marcias case this lack of immediacy due a rationale state of confidence in her ability to get to safety could have occured which was compounded by shooting the camera to the detriment of paying attention to the ongoing gauge reading compounded by new drysuit/ weighting issue. Lack of panic haste and possible blackout with camera and last minute critter shot as a co influence for an unfortunate chain of events leading to drowning.

 

[AfterDark]

Maybe a true free diver could correct me if im wrong... The urge to breathe is caused by co2 build up.. Hyperventilation reduces co2 but does NOT increase O2... thus if done to far, you actually will not feel the urge to breathe before you blackout

So yes you can hyperventilate to the point where you do not resist the urge to breathe before you blackout... In that case I wouldn't say that they "go through the urge"







Sent from my Nokia Lumia 920

We were taught this in scuba class way back in the 1960's. Purge enough and the urge to breath will not happen and blackout will occur.

 

[DevonDiver]

So yes you can hyperventilate to the point where you do not resist the urge to breathe before you blackout... In that case I wouldn't say that they "go through the urge"

Except, on very rare occasions, free-divers don't black out. They remain conscious. During which time, CO2 continues to accumulate... as does the desire to breath.

(btw.. this is distinctly off-topic now).

Marcia was found in shallow water with a full BC. Everyone assumes this is where she passed away. Wrong.

Correct. This is an assumption. However, there are no reports of seeing Marcia reach the surface. The depth was only 3m.

The Buddies had a hard time swimming her remains to the surface. Please remember that it is possible while unconscious for the body to ingest water. Once the laryngospasm has ceased then water will enter the lungs in addition to the stomach thus the person may have an additional 6lbs or 3kg of extra weight from sea water.

Correct. This is largely irrelevant. Her negative buoyancy is not in doubt however (the full wing).

In the Photographs posted - ignoring the differences between the bouyancy methods, Marcia seemed to be neutral at 12m, indeed she will have carried out safety stops prior to the incident? Surely if you are neutral at 12m (even with a full wing) then you are buoyant at below 6m?

Buoyancy was supplied by drysuit and BCD. The BCD itself wasn't sufficient to attain neutral buoyancy given her weighting. If out-of-air, then she couldn't add more air to the BCD and was, thus, unable to attain the buoyancy she needed.

If she had ascended, and in doing so, opened her exhaust valve, and forgotten to close that valve upon re-descending, then the drysuit would have emptied (the 'vacum pack effect').

There has been much debate over the Gas reserve, as I understand it (feel free to correct me) If you dive on PSI then the convention is that you come up with 500 (30bar) where as the metric system is that you surface with 50bar (725psi) - If Marcia dropped down on 50bar and swam off another 20bar (which at those depths should take a while) she would still come up with a safe margin.

It is not uncommon for SPGs to be inaccurate at low pressure. They can report 10-20 bar pressure when empty. This is one reason that makes keeping a substantial reserve a very good idea. Every training agency on the planet, and SPG manufacturers, recommend a safe reserve of 50bar/500psi.

Excusing that reserve lower is probably a process that Marica chose to engage in. Let's not advocate replicating that.

Given that all accidents are a combination of differing factors and removing just one of the factors makes the accident survivable I can't help wondering that there is a small piece of the jigsaw missing...

I believe the other pieces of the jigsaw are entirely psychological. Complacency and over-confidence. (see my previous posts).

 

[RTee]

I do think that there is a phenomenon of bowing to someone who is viewed as a "senior" diver. In fact, I know there is, because I've been guilty of it myself. How hard do you push somebody who "outranks" you in training AND experience, when whatever it is they are doing doesn't sit well? I know how hard it is to be the squeaky wheel in that situation, and honestly, this accident drove it home yet again, that when something doesn't feel right, you shouldn't shut up about it. But you can only do so much, and I can easily imagine being in a situation where, having chased a diver who repeatedly refused to stay together enough times, I'd shrug and let them go off. It hasn't happened, but I can imagine it happening.

I find it hard to put much responsibility for this accident on the shoulder of the companions. This diver knew what she was doing, was requested not to do it, and did it anyway.

Agree but have to admit that I find the words Bowing and Outranks a bit strong for an activity that we do as a hobby and for enjoyment but I understand your context. I consider myself to be pretty easy going and to adapt quite easily to diving with more experienced or less experienced diver as long as I and the other divers are treated as equal partner and are comfortable with what we are trying to achieve. (scuba diving instruction is something else but even as a student, respect has to be a two way street as well)

Having said that, the one thing I will not do is to always subjuge myself to somebody's wishes under the pretext that he or she might be a more senior diver. It has to be enjoyable for everybody. When it becomes clear that an individual's opinion, dive profile, etc always has to prevail, then my fun factor rapidly drops to 0 and I start looking at other more enjoyable diving options. Normally, my GF is my dive buddy and we tend to dive as part of a group of very good people whose experience, certifications and seniority will range from OW to instructors. As part of the pre-dive social chatting (and it is really the best word to describe the initial discussion that occurs), everybody will be asked what specific dive profile or dive objectives they may have in mind, who wants to be leader of the dive (normally we are all acquainted with the local dive sites anyway), who is diving with who and then we proceed with the more formal briefing. Sometime one or some divers will bring underwater camera set-up and that gets taken into consideration as well. The bottom line is that we all have our say in the matter and everybody is treated equally. Today you could be leading the dive and I will be following. Tomorrow, it might be the other way around.

Bowing...you can only tell someone so many times as to what you like, dislike, are comfy with or the other way around. Based on all my reading thus far, the accident did not occur on the first day they were diving together. It also seems pretty clear to me that, during that the vacation, Quero wanted to dive a certain way and projected that mindset in a verbal and non verbal ways to the other members of the group which was not what they had initially envisionned or were accustomed to. In this case, it seems fairly clear to me that the last thing she wanted was a close by dive buddy, let alone a remora.

 

[je76]

I've read the whole thread over the last 3 days and want to analyse the relevant facts (or Statements) that cause me confusion

1. Marcia was found in shallow water with a full BC. Everyone assumes this is where she passed away. Wrong. This is where she ended up. Since she was negative she would have sunk once hypoxia set in - this as I understand (and it has been mentioned before) can vary from person to person, but under stress can be fast.
2. The Buddies had a hard time swimming her remains to the surface. Please remember that it is possible while unconscious for the body to ingest water. Once the laryngospasm has ceased then water will enter the lungs in addition to the stomach thus the person may have an additional 6lbs or 3kg of extra weight from sea water.
3. In the Photographs posted - ignoring the differences between the bouyancy methods, Marcia seemed to be neutral at 12m, indeed she will have carried out safety stops prior to the incident? Surely if you are neutral at 12m (even with a full wing) then you are buoyant at below 6m? (Assumes no equipment malfunction). Even given that she was new to the equipment one must assume that Marcia would know when she was really too heavy? That said I believe those more familiar with Dry suites have give a plausible explanation with suit venting, given that it was reported that the suit did not flood.
4. There has been much debate over the Gas reserve, as I understand it (feel free to correct me) If you dive on PSI then the convention is that you come up with 500 (30bar) where as the metric system is that you surface with 50bar (725psi) - If Marcia dropped down on 50bar and swam off another 20bar (which at those depths should take a while) she would still come up with a safe margin.

These are the points which I've been going over and over. Roturer's synopsis on page 14 (post 131) still seems to be the most likely cause given - however my one concern is that with a full tank then on surface entry surely it would become apparent that you couldn't hold on the surface and that something must be wrong with the set up?

Given that all accidents are a combination of differing factors and removing just one of the factors makes the accident survivable I can't help wondering that there is a small piece of the jigsaw missing...

Caveat 1: I have experience in Air accident investigation so tend to mull over details more than most...

Personal comment:- This incident has made me completely re-evaluate all my diving practices - which as others have pointed out is the greatest legacy of this sad incident - RIP Marcia

1) Based on this we can conclude there was some weight ratio issue between her gear and the amount of weight she had donned.
2) This is a good point. A few lbs can make all the difference. So this calls into question preparation. If her wing wasn't sufficient to raise the extra 6 lbs of fluid she inhaled what would have happened say if her dry suit had flooded?
3) The question I ask is, "Was she neutral because of a combination of lift between her wing and dry suit?"
4) Gauges that low are inaccurate. I like to think of doing anything but being on or near the surface once I get this low as taking a "Kamikaze reading".

The small piece of this jigsaw for me is what happened to prevent her from ditching weight. Had she ditched it wouldn't have mattered how much water she swallowed she probably would have gotten a non-stop ticket to the surface.

 

[phoenix31tt]

Except, on very rare occasions, free-divers don't black out. They remain conscious. During which time, CO2 continues to accumulate... as does the desire to breath.

(btw.. this is distinctly off-topic now).

when they don't black out, and they get the desire to breathe... this means they didn't push hyperventilation past that specific point... knowing where that point is for you and how not to push pass it is something free-divers train for...

either way you are 100% correct.. totally off topic lol