A_Person

Apparently you don't read replies to your posts. So I'll email this as well as posting it here for the record. I have automatic copyright to all the posts that I've made to this forum. I now request you to delete all those posts, or at least edit them all to "XXX" (or similar), by close of business on Friday 20 July your time. If that does not occur, I'll engage local US representation to pursue that issue on my behalf. Thanks in anticipation

Obviously we have different ideas about what constitutes intelligent argument. Please delete my account. If you need a formal request to that effect, say here how to submit that.

You said the brits were risking their lives. I said they weren't, at least to the extent that you believed - and explained why in exhaustive detail. But you disagree, based on qualifications and experience that could roughly be described as: zero. I'll speak to doctors Dunning & Kruger and see if they can fit you in next week for a chat.

Try to follow along.

You: the two Brits were risking their lives.

Me: Not really, they'd have been following standard cave diving safety protocols.

You (effectively): Well, a Navy Seal just died, so that proves that it's dangerous.

Me: There's evidence that the Navy Seals weren't trained cave divers - they certainly didn't seem to be equipped as such - so all it proves is that cave diving is dangerous to those without specific training and/or proper equipment - navy seals or otherwise.

You: you'll change your tune if one of the brits dies!

W-T-F?

Here's a short list of how the diving equipment in some of the photos is absolutely noncompliant with proper cave diving equipment. This implies to me that they are not trained cave divers, and consequently, the risks they unknowingly took were enormously greater than the risks the two brits took:

(1) Single tanks! Fine in recreational diving, because if something goes wrong with your air supply (tank valve fails, hose bursts, regulator falls apart, whatever), you can go to your buddy for air, or at worst, bolt to the surface. No good in cave diving, where there isn't any air at the surface, and your buddy might be 20 meters away at the other end of a tight restriction. So all cave divers use twin tanks. We also follow gas management rules designed to let us survive the following two scenarios: (a) At the point of maximum penetration, you get separated from your buddy, and simultaneously, one of your two tanks completely fails; and (b) at the point of maximum penetration, you're still with your buddy, but both of your (or his) two tanks fail. Diving on a single tank is fundamentally noncompliant with all those standard safety protocols.

(2) Hoses curving out around their heads. These are common in recreational diving, but a serious entanglement hazard in cave diving. Cave divers route all their hoses tight-in, to reduce entanglement risks. This is especially important in low or no visibility diving. No properly trained cave diver would leave the house with hose routing like that in some of those photos. Even if an experienced cave diver was forced to use that gear by circumstance or in a dire emergency, she'd fix that up before she got in the water.

(3) K-valves! The top of each tank has a valve, onto which you attach the first stage pressure reduction regulator. Those valves come in two styles: K-valves, and DIN valves. Each style has a rubber O-ring to seal the regulator onto the valve. With K-valves, the O-ring can squeeze out, causing the attachment to fail. That's rare, but can happen. Bad luck if you're a kilometre into the cave - on a single tank - with your buddy at the other end of the restriction!! With DIN valves, the O-ring is trapped entirely within the valve body, so it can't pop out. For that reason, few if any properly trained cave divers would use K-valves.

(4) Funky hand held torches! They probably throw a nice wide beam, which is good for recreational dives. But cave divers need narrow beams (to cut through the murk, and facilitate signalling); with multi-hour durations, and hands-free attachments so you can use that hand for other tasks.

In summary, someone who is an experienced brain surgeon, gets into a Formula One car, prangs it, and kills himself. To me, that doesn't say much about the safety of properly trained and qualified Formula One drivers.

But you say that the death of a person, who may have had zero formal training in cave diving, says something about the safety risks the two brits took? Perhaos two of the most experienced expedition cave divers in the world?

I think you do not understand the issues. I don't intend to reply again.

Given that I'm sitting at home watching TV - and they're all busting their asses off in the cave - it's hard to discuss this without being disrespectful to them - which I certainly don't want to be. But anyway...

Looking at some of the photos, lots of the gear they are wearing is ordinary recreational gear - nothing like what an experienced cave diver would use. So it raises the question, in my mind, as to whether their navy seals actually do have any formal training in advanced cave diving. Combat diving is unlikely to be the same thing.

So the very unfortunate incident might actually support my previous comment, not contradict it. Cave diving is very dangerous to the untrained or improperly equipped. But proper training and equipment can mitigate those dangers. The two brits would not have been wearing anything like the kind of gear in the photos :-(

Again, kudos to the people on the spot, doing their best.

I don't know that cave at all, but from various descriptions, it sounds like they may have had to crawl through several restrictions to get where they are. So it's not a matter of walking through vertically to get in, then just being gently pulled back out the same way It's a matter of squeezing through on your belly to get in - then to get out, reversing that, in unfamiliar bulky diving gear, completely underwater (literally no air anywhere), in pitch blackness, and zero visibility (as in, you'd not see an inch beyond your mask, even with a powerful torch). It's not easy even for experienced cave divers. I once went through a hole, then couldn't get back out! I tried for 10 minutes. At one point I even considered removing my tanks and pushing them out first. It eventually happened, but it gave me a scare - and that was in crystal clear water, in a site I'd dived before! Its just not as simple as people seem to assume. But again, I don't know the cave in question, I'm just going from what I've read.

You can't be serious. Taking 13 people, with an absolute maximum of Open Water level training (if that), back out through hundreds (or thousands?) of meters of low or zero visibility diving, including (apparently) tight restrictions, without risking the lives of all concerned? Aint gonna happen - unless the water level drops to the point where they can just float back out.

That's really not so. Cave diving has well established protocols for safe navigation, gas reserves, entanglement management, and so on. There's no way they'd have gone significantly outside those protocols. Those brits are highly experienced expedition cave divers, and undoubtedly pushed it further than a weekend warrior like me would do. But they really wouldn't have been dicing with death, as it were.

> claustrophobia can express itself in different ways

Too right. I'm a reasonably experienced cave diver, and regularly dive in a system of 11km of intersecting fully-underwater tunnels, with the single entry/exit being a small pond, a few feet across, in a small, underground air-filled cave. I'd typically go 700-800 meters out, with a dozen navigational decisions along the way (left? right? straight ahead?), then have to reverse all that to get back out. But a few years ago I had an MRI, where you're wheeled into a narrow metal tube, on your back, with your arms pinned to your sides, with the tube an inch away from your face. Result: GET ME OUT!! GET ME OUT!! I had to be wheeled back out & take a break, before I could grit my teeth and try again. I absolutely hated it. I told them I was an active cave diver, but I don't think they believed me :-)

I did know that, but I'm not sure how that applies. In your scenario, the tank ruptures, there's virtually no water expansion, so nothing happens. In my scenario, the tank ruptures, the internal gas content instantly expands by (say) 250 times, creating a massive force which I assume is transmitted virtually undiminished, through the water, to the sides of the container, which promptly explode outwards. I do accept that some of the force will go upwards, but I believe the container will still explode. Not really trying to disagree, just trying to get my head around it :-)

But only by 3% - so I still won't set up my chillout lounge right next to the tank fill station! :-)

I'm no scientist and you may well be right. But I'm skeptical of your statement that "much" of the blast would be directed upwards. If you look at the pictures of tank explosions, they often show the entire room flattened right to floor level - not a big hole in the roof and minor damage everywhere else.

It's always surprised me how many people do not know that water is incompressible! For example, when someone is filling a scuba tank, it's common to put the tank in a large, often metal-sided container of water. When asked why, the shop staff member will typically say: "In the unlikely event of the tank blowing up, the water will absorb the force of the explosion." But in fact, water being incompressible, it will absorb approximately 0% of that force - which is then transmitted undiminished to the metal walls - which then explode like a giant hand grenade, promptly maiming or killing everyone standing nearby! The purpose of the water is instead, to absorb the heat from adiabatic compression, and keep the tank cool.

The other day I dropped in on a local scuba store that I've patronised as a customer and/or instructor for nearly 30 years. They've changed hands recently, and had a few new folk behind the counter. I waited for over 5 minutes, unacknowledged, literally 3 feet away, while two of these bozos had a private conversation. Then, when they eventually dragged themselves out of their customer service torpor - it got worse! And not for the first time. So I walked out, and finally decided to never go there again - and to start bagging them (instead of recommending them) whenever I could.

Scuba stores have traditionally survived on markups from equipment sales. Everything else is a loss leader. But now, people can get a wider range, of better equipment, delivered faster, at half the price - via the internet! Yet STILL, bozos like those guys can not be bothered to service someone who's made the effort to walk in the door!

It makes me wonder how many small businesses go under because of good ol' garden variety hopeless customer service, rather than anything else.

> Wow, congrats on insulting people

I posted a detailed exposition of my own approach to interviewing. I expected nothing more than some intelligent comments thereon.

In response, someone says I'm "prejudiced", and why would he "give a fuck" about my concerns; another says my concerns exist "in a parallel universe"; and another says my views are "religious"!

Equeeze me if I don't take well to copping random insults in what is meant to be an intelligent discussion forum. Particularly from people who've contributed zero to the discussion so far - like you! I suggest you get out of the basement and get some exercise. Maybe ask your mum for a bike?