Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A man who ran out of air at the bottom of the ocean

bbc.com

Post reply on HN
Print view View original

111–120 of 180 posts

Re: A man who ran out of air at the bottom of the ocean

#111

Post by LeifCarrotson »

jdietrich wrote: post #89
latch wrote: post #5

Reminds me of the fantastic movie The Abyss (1)...vaguely recall a similar scene where there's N tanks of oxygen for N+1 people, so they submerge 1 of the crew to lower her (i think) metabolic rate. Curious why they don't have emergency unmanned drones with the crew or why they don't have emergency tanks at their work site (which he was able to get back to) (1) - Not sure how well it has aged ( https://en.wikipedia.o…

>Curious why they don't have emergency unmanned drones with the crew or why they don't have emergency tanks at their work site (which he was able to get back to) There was a UUV in the water, which helped to locate the casualty but wasn't capable of performing a rescue. Bailing out to open-circuit SCUBA doesn't help for very long, because of the immense pressures involved. As you go deeper, you need more pressure to…

> A cylinder that lasts for an hour near the surface will only last for a couple of minutes at 100m

And unfortunately for saturation divers, you can't pressurize cylinders on-site to make up for the difference.

Pressurizing your tank to 210 bar (which puts the same stress on the cylinder walls as 200 bar at the surface) doesn't change the factor-of-10 increase on the other side of your P1V1=P2V2 balance.

Not to mention that you need even more air for decompression time...

Re: A man who ran out of air at the bottom of the ocean

#112

Post by Symmetry »

brokenkebab wrote: post #110
garmaine wrote: post #65

Earlier quoted context omitted.

You have perfect knowledge of future technologies?

Doesn't it sound similar to "Prove that I cannot win a billion!" from someone who spends money in casino?

There's a big difference between telling someone they aren't going to win in the casino and telling them they have "zero chance" of winning. The later is false and is probably an ineffective argument because it's obviously false.

Re: A man who ran out of air at the bottom of the ocean

#113

Post by gus_massa »

Joakal wrote: post #17

Question for the medical readers: a person dies when brain dies from lack of blood flow, right? So all those injuries, say a car crash where heart will stop soon. 1) Disconnect the head from body 2) plug it into a machine that supplies blood, etc 3) the body is repaired 4) reattach head to body. Overlooking the obvious trauma, is this possible? While extreme/traumatic, I think it could be more reliable as other facto…

Better than cutting the head (or the body) is to reduce the temperature and induce an hypothermal effect like in the article. It is used in some surgeries https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_a... (Don't try this at home.)

Re: A man who ran out of air at the bottom of the ocean

#114

Post by nradov »

TheOtherHobbes wrote: post #94
idlewords wrote: post #44

Earlier quoted context omitted.

The beginning certification level is 60 feet. You unlock the deeper limit after additional training, and it includes performing a three-minute "safety stop" at 5 meters. 60 feet is about as deep as you want to shoot to the surface from (and if memory serves the limit they give in training is 30 feet, or 2 atmospheres).

I've always been fascinated by how hard diving is. 60 ft seems like a completely trivial depth - about the length of four cars - but already there are non-trivial risks. And from there it rapidly becomes more dangerous and complicated and just plain hard to stay alive.

It's not that hard. If you're interested then go ahead and sign up for a basic open water class. Most people can pass.

Re: A man who ran out of air at the bottom of the ocean

#115

Post by namibj »

cstrat wrote: post #77
killjoywashere wrote: post #23

Earlier quoted context omitted.

Getting cold probably saved his life by reducing the metabolic burden. This is done intentionally during certain surgeries, such as aortic aneurysm repairs. It also informs the ER standard: you're not dead until you're warm and dead. Also, it's staggering how much oxygen can be dissolved into your system at depth. The Navy did some experiments where they put pigs in a chamber, pressurized them to something obscene, l…

Yeah that's amazing isn't it. Replacing blood with water sounds like magic though. The blood does more than just carry oxygen doesn't it? I was just saying though, if he did have more oxygen down there he would have had to be awake for that freezing experience...

Or with blood plasma, maybe.

Re: A man who ran out of air at the bottom of the ocean

#116

Post by folkrav »

dig1 wrote: post #102
jdietrich wrote: post #88

Earlier quoted context omitted.

At sufficiently high partial pressure, it's toxic. https://en.wikipedia.org/wiki/Oxygen_toxicity Nitrogen becomes narcotic at high pressure; breathing normal air at 30m is like being tipsy, but below 90m it can be fatal. https://en.wikipedia.org/wiki/Nitrogen_narcosis

Nitrogen narcosis is usually called "drunkenness of depth" (if I translate this correctly), because it produce effect like you are drunk. I've seen and heard many stories of experienced divers that would do silly things due this effect; that is why you always have to have partner with you and the rest of the crew near by. This effect is highly dependent of person and I've seen guys goes beyond 40m without getting thi…

I'm no professional diver, but did a bunch of dives between 60-100ft, and it seems like it can start happening to me around 70-80ft. Experienced divers will be more conscious about when it happens to them, and will plan their actions accordingly.

It's pretty eerie. It's _literally_ like being drunk, but you happen to be strapped to an oxygen tank with 100ft of water over your head, and could get extremely sick if you did something too stupid.

It's actually a pretty safe activity, given you follow safety rules. It's however pretty easy to stray from them.

Re: A man who ran out of air at the bottom of the ocean

#117

Post by saalweachter »

OJFord wrote: post #92
ChrisRR wrote: post #86

Earlier quoted context omitted.

Even speaking as a brit, your mixture of metric and imperial and metric fascinates me. I personally would've written 150lb, 6'6 tall, 1ft deep, 37 to 0 degrees

150lb? That always strikes me as distinctly American, as opposed to 10st 10lb.

I'm so glad America got away before y'all went stone-crazy.

Redefining the hundredweight, seriously?

Re: A man who ran out of air at the bottom of the ocean

#118

Post by Robotbeat »

ekianjo wrote: post #67
Robotbeat wrote: post #51

Earlier quoted context omitted.

Not for cryogenics, unfortunately, but yes for hibernation. NASA has funded the study of medically induced torpor for hibernating humans for deep space exploration: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201800... If we ever do crewed interstellar travel, even if we can get the trip time down to 50 years or so, we’ll probably want something like this. But it’s useful even for Mars trips since you can f…

Would you need to feed nutrients people during hibernation or is that a state of extrenely low metabolism?

It’s answered in the PDF. There’s nutrient delivery, but metabolic rate is halved so there’s less required.

Re: A man who ran out of air at the bottom of the ocean

#119

Post by Robotbeat »

justinclift wrote: post #78
Robotbeat wrote: post #51

Earlier quoted context omitted.

Not for cryogenics, unfortunately, but yes for hibernation. NASA has funded the study of medically induced torpor for hibernating humans for deep space exploration: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201800... If we ever do crewed interstellar travel, even if we can get the trip time down to 50 years or so, we’ll probably want something like this. But it’s useful even for Mars trips since you can f…

Interesting. That PDF doesn't seem to include increased radiation exposure while having a slowed ability to repair the damage. Wonder if that's just because it's not viewed as important?

There may be less oxidative stress as well, so it’s tough to say what wins out. Anyway, there are methods of providing radiation shielding to occupants as well.

Re: A man who ran out of air at the bottom of the ocean

#120

Post by Waterluvian »

ayakura wrote: post #4

>If you lower the brain temperature down to 30C (86F), it can increase the survival time from 10 to 20 minutes. If you cool the brain to 20C (68F), you can get an hour. Wow, I actually didn't know this until now. Is this method used anywhere in medical procedures to resuscitate or prolong life?

"You're not dead until you're warm and dead." Is a quote that stuck with me. I was reading an article [1] about a person who froze to death and made a practically complete recovery.

By the way this story is a must read.

[1]https://www.thestar.com/news/insight/2017/02/19/this-queens-...

Post reply on HN