Overhead environments and open water scuba divers

[MXGratefulDiver]

Echoes of the David Shaw story.

In both cases the divers were on trimix. HPNS is the most likely culprit ... that and CO2 from exertion they hadn't planned on. In Shaw's case in particular ... since it was evident in the video.

Oh, and Shaw would've been the echo, since he died 10 years after Exley did ...

... Bob (Grateful Diver)

 

[mathauck0814]

Only read about the first three pages of posts...

It's all about awareness - or the complete lack thereof. How many newly minted divers believe they have good buoyancy skills (all the while are bicycle kicking and stirring up the bottom)? Most new or old, infrequent divers are tunnel visioned, staring at the fins of the diver in front of them between intermittent distractions of, "oh look - something shiny!" Expecting these same divers to be aware of a #28 guideline or the composition of bottom material is likely unrealistic. In fact, I'd say that expecting them to know that they've entered an overhead (especially one with a large opening) ahead of time is probably asking too much in some circumstances (the arch at San Clemente island comes to mind).

Not allowing lights is a good start - but that requires enforcement. If enforcement were a reasonable option, we could enforce the "no overheads without training" rule. Unfortunately this message necessarily belongs in basic training and dive briefings.

I am happy to say that in the last year, I have heard more and more operators state, "there is feature X on this dive - please do not go there if you are not trained and equipped to do so". That's a step in the right direction, but you're never going to be able to weed out 100% of the vacation divers who truly believe that there just isn't all that much to safely doing this sport.

You can solve some of the problem with education - be it in training or on a briefing - but so long as divers are sentient, there are going to be those who lack the awareness they can get hurt.

 

[boulderjohn]

Oh, and Shaw would've been the echo, since he died 10 years after Exley did ...

IMO, Shaw's death was a result of an error in judgment formed during the pre-dive planning. He made a fundamental mistake that almost any trained cave diver I know would not have made, and he could not blame it on narcosis. If he had not let his light dangle to the cave floor while working, he would not have become entangled and would not have had to struggle to free himself. A mistake like that is baffling, since the error seems so obvious in post-dive analysis.

It is the kind of mistake an untrained diver would make, which is why people talk about the importance of training.

 

[rakpix]

Looking back through my logbook - and with the benefit of recent cave experience - I'm forced to admit I entered 'overhead' environments without 'overhead' training many times early in my career. Whether it was my first wreck dive (5/31/2010) or a coral swimthrough (6/1/2010), a flooded mine (8/8/2010) or an abandoned boat dock (1/23/2011) there were two things in common among all these experiences:

1) For a period of time during the dive, I did NOT have direct vertical access to the atmosphere.
2) At NO POINT during the dive, did I feel afraid, anxious, or really at all cognizant of the risks I had taken.

I am still shaken by my ignorance, and the consequences the overhead environment can mett out on overconfident divers like myself. However, it is important to remember that cave-trained divers still face these same challenges. We are just as susceptible to human flaws and temptation. It is, in fact, more important for the cave-trained diver to always step back and reassess their dive plan, and ask themselves one simple question:

"I am being honest about the risks I will assume if I complete this dive?"

This is the strongest argument I can pose in favor of team-only diving. It is so easy for a diver to lie to themself about the risks in diving and the consequences of those risks; to rationalize their choices ignoring every tennent of their training. It is another thing entirely for a diver to lie about those risks to their buddy, selfishly jeopardizing the team's safety for one more thrill.

 

[stairman]

I don't understand this. He was breathing trimix when he died.

A/C N10 - Incident Reports (scroll down a bit)

I realize that but at depths not yet recorded. That is a pioneer. A dead one but nonetheless.

---------- Post Merged at 06:28 PM ---------- Previous Post was at 06:28 PM ----------

I don't understand this. He was breathing trimix when he died.

http://www.iucrr.org/aa_misc.htm (scroll down a bit)

I realize that but at depths not yet recorded. That is a pioneer. A dead one but nonetheless.

 

[MXGratefulDiver]

IMO, Shaw's death was a result of an error in judgment formed during the pre-dive planning. He made a fundamental mistake that almost any trained cave diver I know would not have made, and he could not blame it on narcosis. If he had not let his light dangle to the cave floor while working, he would not have become entangled and would not have had to struggle to free himself. A mistake like that is baffling, since the error seems so obvious in post-dive analysis.

It is the kind of mistake an untrained diver would make, which is why people talk about the importance of training.

Actually that mistake was the result of another, in hindsight, error (one of several ... which are easy to see when looking back from the comfort of a keyboard). The reason for the light mistake is that Shaw took an unfamiliar piece of equipment on the dive with him ... a helmet cam ... to video the recovery. Another mistake that compounded the problem was that there was never a contingency plan for what he would do if Deon's body became buoyant ... which it did. At that point, Shaw needed to use two hands. Previous to this dive, he was used to looping the light cord behind his head, so the light would hang down beside his chest. The helmet cam prevented this. He'd already overstayed the plan, and was hurrying, building up CO2 due to the exertion. You can hear the results in the video. Narcosis, HPNS, CO2, and a timetable he'd already exceeded ... all contributing to a narrowing of perception and a focus on the "problem" of getting Deon's body in the bag. He didn't have the bandwidth to think about what to do with the light ... so he dropped it.

Error in judgment, true ... but the error, really, was not giving up when he realized Deon's body wasn't going to sit quietly on the bottom so he could put the bag in place the way he'd planned. Everything that happened after that just led him to a state he was physiologically unable to cope with. The light was just the last link in the chain ...

... Bob (Grateful Diver)

 

[JamesK]

Well, his knowledge, or lack thereof apparently killed him. Or as they like to say on SB, he dove beyond his training.

Big difference in not having the knowledge because no one has ever done it before, and not having the knowledge because someone refusing to learn from the mistakes made by others who have done it.

I pulled this one over from another thread I posted on:

It happened in the summer of 1978. The equipment consisted of a Healthways steel 72, Aqua-Lung Aquarius reg, White Stag Deep SPG, USD Atlantis mask, USD Otarie fins, 5 pounds on a USD weight belt, USD diver's knife. I had just bought the Aquarius and this was my first dive with a single hose reg.

One year, when I was just a kid, my family went to Tennessee for vacation. While we were there, we visited Tuckaleechee (sp?) Caverns. From that time on, I was fascinated by caves. By the time I reached my early twenties, I had spent thousands of hours exploring underground and crawling through some pretty tight places. I even became a member of the Tri-State Search and Rescue Team, specializing in cave rescue.

So, when my friend and I discovered a cave in the rock wall of a man-made lake where we were diving (I'm not going to say where because I don't want to tempt anyone), we decided to check it out.

Yeah, I know. We were young and stupid. I should've known better.

Anyway, Fuzz led the way and I followed him into the cave. The passage was tight and Fuzz kicked up the sediment to the point where I couldn't see squat. I groped along behind him, hands out in front, trying to keep up. Then, I suddenly found myself in clear water and Fuzz was nowhere in sight. I switched off my light to see if I could detect his light. Nada. Black as Hades. At that moment, I felt my tank grate against the ceiling for an instant, then come free.

I realized that I must have taken a side passage and was separated from Fuzz. I started to back out, but couldn't. I was stuck. My tank was lodged in a depression in the ceiling and I couldn't move. My first thought was to simply unbuckle my harness and slip out from under the tank, then pull it out of the cave after me, but the passage was too tight and I couldn't get my hand down to my waist to release the buckle. I thought about cutting the harness away at the shoulders but my knife was strapped to my leg, out reach.

Out of options, all I could do was watch the needle of my SPG as my air slowly ran out. I thought about my parents and my girlfriend. I thought about how stupid I was and I wondered how long it would be before someone found my body.

At 500 psi, it became more difficult to breathe. At 300 psi, my J valve would cut off and I couldn't reach the rod to turn on the reserve. Panic was about to set in when I felt something moving along my left leg. It moved up to my waist and I felt a tug at my harness buckle. Then, something grabbed my ankles and yanked me backward and free. I pulled my tank after me and followed Fuzz back out to open water. On the way, I had to open the reserve.

I haven't tried cave diving since.

Scary story there. I still remember the first time I got wedged in somewhere and the first time I was in a silt out in an unlined side tunnel. Both were pretty sobering experiences, but I am glad I was able to make it out without panicking.

 

[jmneill]

Actually that mistake was the result of another, in hindsight, error (one of several ... which are easy to see when looking back from the comfort of a keyboard). The reason for the light mistake is that Shaw took an unfamiliar piece of equipment on the dive with him ... a helmet cam ... to video the recovery. Another mistake that compounded the problem was that there was never a contingency plan for what he would do if Deon's body became buoyant ... which it did. At that point, Shaw needed to use two hands. Previous to this dive, he was used to looping the light cord behind his head, so the light would hang down beside his chest. The helmet cam prevented this. He'd already overstayed the plan, and was hurrying, building up CO2 due to the exertion. You can hear the results in the video. Narcosis, HPNS, CO2, and a timetable he'd already exceeded ... all contributing to a narrowing of perception and a focus on the "problem" of getting Deon's body in the bag. He didn't have the bandwidth to think about what to do with the light ... so he dropped it.

Error in judgment, true ... but the error, really, was not giving up when he realized Deon's body wasn't going to sit quietly on the bottom so he could put the bag in place the way he'd planned. Everything that happened after that just led him to a state he was physiologically unable to cope with. The light was just the last link in the chain ...

... Bob (Grateful Diver)

Well said Bob. You and I have some varying opinions and seem to often see things from totally different angles but this post really nails it. Breaks a ten minute video down to the bare facts in a well spoken thirty second read.

---------- Post Merged at 08:59 PM ---------- Previous Post was at 08:46 PM ----------

Big difference in not having the knowledge because no one has ever done it before, and not having the knowledge because someone refusing to learn from the mistakes made by others who have done it.



I understand entirely. The post you reference was a result of pent up frustration. James, you are aware of my opinion on this type of thing. As far as I'm concerned the president should have been at his funeral. Currently as an OW diver I would just like to be able to take certain overhead risks without the scrutiny I often see on this board. That said, as soon as the Suwannee river recedes I will be on a three day cavern course and will post on the experience for the very few scubaboard members who haven't already taken it. I've got a real good instructor and am looking forward to whatever can be taught and retained in three days. Yes, one extra day over the minimum

 

[grandizer52]

you guys ever seen new divers grab gear for a "BUDDY" (the new guy thinking he's instructor lever) and do stuff like this? either take them deep, or hea...it's only a little cave...

 

[FPDocMatt]

Here in Cozumel (Cozumel Invasion, Hotel Cozumel) we went on several "swim-throughs". A couple of them were rather long (about 50 feet I'd guess), with no way to the surface along them (Palancar Caves and Santa Rosa Wall). There were 2 places where no light was visible, though these were only for about an 8-foot stretch on one and a 4-foot stretch on another. Where there was light, it came from openings in the ceiling, but in most cases these openings were too small to fit through.

It may be that I was not qualified to enter these swim-throughs. I don't know. I have open water, advanced open water, rescue and nitrox certification. At the beginning of the week I had 22 dives, now 35.

But whether I was qualified or not, I felt perfectly safe on these swim-throughs, and would not have traded the experience of them for anything.

There was lots of sand on the floor of these swim-throughs, which could have certainly been stirred up if anyone in front of me had been careless with finning. In some cases, there were 2 paths that could be taken.

One other thing: The guidelines presented by TSandM in the OP are great guidelines, but in most cases you don't know ahead of time what's inside the overhead environment. You're just following a DM on a guided dive. I can imaging stopping the DM on the boat and asking, "Are there swim-throughs? If so, what are they like? Do they have multiple paths? Do they have sandy bottoms? How long are they"? I guess that would work. But more commonly you're going to be on a guided dive without any prior discussion of swim-throughs, and the DM goes into one without prior discussion. Then what do you do? Get out your slate and write, "TSandM told me I shouldn't follow you." Yeah right.

Maybe I'd have a different opinion if I'd been on some really scary swim-throughs.

On the other hand, I had the utmost confidence in my DM on this trip. After reading here about some less-than-conscientious DM's, I wouldn't want to enter any overhead environment with that kind of DM.