Two missing on submerged Great Wall - China

[Norwegian Cave Diver]

I will take the electrocution question off the list.
Making the assumption that they were aware of the cold - depth - poor visibility - possible fishing nets - then the dive plan would have included the conversation of - we need to stay close enough that we can either see each other or at the very least see each other’s lights. Sounds like they were not close to each other when they were found? That is strange for me. Should have been someone is lost or entangled and the other diver surfaces. One lives. Or - One is entangled - lost visual contact. Second diver is looking and never finds buddy? Doesn’t surface before running out of gas. Or gets entangled too. Haven’t read that either diver when they were found was entangled.

 

[kelemvor]

And just as I had seen it coming... Chinese officials will put it on some illegal / unlawful action as per this article the blaming is already going on

"Local police have not yet revealed any information on their investigations. The actual cause of death will be confirmed during an autopsy. In the meantime, netizens and diving professionals are now arguing about whether the two divers were qualified to conduct the survey and mapping mission.

An officer from the Hebei Bureau of Geo Information told Red Star News that, according to China's Surveying and Mapping Law, underwater surveys require special qualifications and applications, as it is illegal to map the Great Wall without approval from relevant organs.

Some netizens are also arguing that GUE, as a "foreign organization," are responsible for their "illegal activities" in China, including the deaths of the two divers.

But others say it is normal for Chinese divers to possess international certificates as diving has only just entered China in the past decade. The team is no more than a private diving club, whose members have certificates from the same organization. GUE has not responded to media inquiries so far."
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Yikes! I hope that idea doesn't gain any traction. Given China's track record in similar situations, I bet anyone in China with a GUE card is at least considering leaving right now. Scary stuff.

 

[Centrals]

Would there be any official statement from GUE china?
It seems to me that the commie chinese official have already identified a "culprit" on this "illegal" activity or someone is beginning to distance himself/herself from this event!

Yikes! I hope that idea doesn't gain any traction. Given China's track record in similar situations, I bet anyone in China with a GUE card is at least considering leaving right now. Scary stuff.

Only five left.

 

[FuAn]

Would there be any official statement from GUE china?
It seems to me that the commie chinese official have already identified a "culprit" on this "illegal" activity or someone is beginning to distance himself/herself from this event!

There is no legal entity called GUE China hence the comment by the officials about illegal activities by a foreign organization. There is a local Chinese gue instructor teaching through his shop and conducting activities like the Great Wall mapping project which contributes to Project Baseline which Is a framework to record outcome of worldwide locally conducted conservation projects.

I’d say gue will be rather quiet on this matter as Chinese officials especially in a rural province will be very quick to blame a foreign organization that from their perspective was operating illegal in China...

 

[willcats]

Let's review some of the information we know:
1. Both divers were found at the bottom.
2. According to the dive computer of one of the divers, he/she were doing deco normally at shallow depth, then had a rapid ascent, but didn't make it to the surface before sinking back down to the bottom.
3. A boat was near the area when the SMB surfaced then the SMB disappeared with the boat. It was later found at the home of one villager.
4. The surface cover was on a vantage point overlooking the area, not in water.

Lesson learned: In an area where diving is not frequently conducted, a boat in the water would be in a much better position to provide support and overwatch for divers.

However, I wonder what could have caused the rapid ascent and how one would become negatively buoyant after such ascent. A flooded loop maybe?

 

[Kevrumbo]

come on... how can you kill two divers with a couple of car batteries other than dropping them on their heads?

Not sure I follow.

I don't have the foggiest idea what happened. I am curious to learn what happened. We may not ever, I understand that. As far as how a diver could be affected by electrofishing if done with 2 car batteries? Pureley DC at 12V, maybe not much effect at all. Don't know. Don't know if it was done and if so how so and by what means. Could a converter have been used, a coil, a generator? No idea. Don't have place, time, test-subject or interest to experiment what could be done and if I or somebody diligently cataloged all that it would have no bearing on if any such thing was done and how (but if I did, I am reasonably certain I could rig something deadlier than a dropped battery, so can others).
That news about what happened, if it comes, sort of has to come from that site...

I still find that electrofishing theory really hard to believe. The guy must have been technically on top of both their heads same time and zapped them.
DC is very inefficient basically used by people wearing a car battery as a backpack two poles in their hand walking around the beach zapping small fish.
For larger setups, an impulse system which would have been strong enough to zapp them in maybe up to 6ft/2m depth would have been big on a boat with a generator and still would have had to be real close from what my impression is.
Check Youtube electrofishing its widely used in the scientific community to do fish counts but the setups are not exactly small. . .

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The Shanghai based GUE instructor who according to several articles is the person who brought up the electrofishing theory now has a imminent interest finding someone elses' wrongful doing.

All it takes is a minimum 300 to 500 mA DC current or 30 mA AC current to induce Cardiac Fibrillation.

It's still possible that this is one of a few plausible scenarios in which two dive teammates can both be quickly incapacitated simultaneously, unable to help each other -although the high voltage generating boat would have to be deliberately very close and nearly on top of them as noted above. One diver by accident gets momentarily caught/entangled in the cathode catch net, the other teammate goes to assist -and they both are electrocuted on contact:

Rule Out Cardiac Arrest/Sudden Cardiac Death due to Ventricular Fibrillation caused by repeated electro-shocks.

 

[Centrals]

Let's review some of the information we know:
1. Both divers were found at the bottom.
2. According to the dive computer of one of the divers, he/she were doing deco normally at shallow depth, then had a rapid ascent, but didn't make it to the surface before sinking back down to the bottom.
3. A boat was near the area when the SMB surfaced then the SMB disappeared with the boat. It was later found at the home of one villager.
4. The surface cover was on a vantage point overlooking the area, not in water.

Lesson learned: In an area where diving is not frequently conducted, a boat in the water would be in a much better position to provide support and overwatch for divers.

However, I wonder what could have caused the rapid ascent and how one would become negatively buoyant after such ascent. A flooded loop maybe?

(3) and (4) don't make any sense at all!!!!
From what I had read so far, the alarm was raised after the second team surfaced before the 1st team(victims) but not the appearing and the subsequent disappearing of the smb. What was the surface support thinking? This is the first time that I ever heard that the "surface cover" was actually on land rather than near the vicinity of the dive!!! The team was diving on a pre-planned route ie. surveying an underwater wall in a reservoir, therefore current was not an issue. A dive boat around would probably have prevent the approach of any fishing boat and also provide quick response to the divers under water.
It would be interesting to hear the story from the fisherman.

 

[kafkaland]

I actually think this is beginning to make more sense now. Speculating, based on what's above, that the victims shot their SMB and were on their shallow deco stop whenever the electrofishing boat approached to check out the SMB. Now you have the electrodes right on top of two shallow divers, and both passed out, their loops flooded, and they dropped to the bottom. Very sad, no matter whether this is how it happened or not.

 

[Centrals]

Speculating only:
1. The fishing boat saw the smb and approached. Didn't notice any bubble around and his greediness got the better of him/her. So he pulled up the smb and left.
2. One of the diver who was holding on the line suffered a massive gas embolism and passed out and .....
3. The second diver saw what had happened or noticed a sinking body so he gave chase forgetting that he was on rich deco mix and suffered O2 tox subsequently.

Any chance to distinguish electrocution, gas embolism and O2 tox during the autopsy?

 

[Pinecube]

Question for CC divers... If fisherman were electrocuting fish and the divers were near by... is it possible it disrupted the electronics of the CC system? Causing the oxygen loop to fail?

I'd like to ask this question too. I'm sure if the computer failed in an obvious way, that the diver would switch to bailout. Are there components that wouldn't cause an obvious failure?

I don't know much about the inner working of a rebreather but I wonder about the oxygen sensor. My understanding is that an oxygen sensors uses a chemical reaction to generate an electrical current which is picked up by the sensor for the computer to read. Could the current from electro-fishing get caught by the sensor enough to cause it to read a higher voltage than normal? The computer may work exactly as intended, just with the wrong input.