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Titanic tourist submersible goes missing with search under way

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Re: Titanic tourist submersible goes missing with search under way

#531

Post by yetanotherloser »

tim333 wrote: post #511
belorn wrote: post #367

Earlier quoted context omitted.

There is a relative recent trend by fire fighters to replace old steel/aluminum cylinders with breathing gas to cylinders made out of carbon (300 bar). They are also used under water in diving. The intend benefit is the reduced weight, but I wonder a bit how the failure mode might be a bit different from steel.

People deal with potential gas cylinder failure by occasionally testing them at higher than their usual pressure. You fill them with water and pressure to say 350 bar rather than 300. At least that's what they do with scuba tanks. Even if designed well they can be dropped, corroded etc. Not sure it's practical to do that with subs.

The advantage of testing pressure vessels with water is that the failure mode is usually less bad than gas (because it doesn't expand through any breach like gas does).

Unfortunately a sub is the opposite of a pressure tank (the pressure is on the outside) so you need a pressure bottle bigger than the sub to test it in. I don't think these are common or easy to come by.

Re: Titanic tourist submersible goes missing with search under way

#532

Post by rsaxvc »

johnwalkr wrote: post #477
Avlin67 wrote: post #350

let me be naive : carbon fiber composite is about tensile stength, not compression strength ? what happens in the ocean ? compression...

Individual fibres, yes. But the composite material is fibres and resin. Plus the vessel is surely pressurized.

Probably not pressurized much in the scale of things.

Humans are incompatible with nearly every gas at 13000feet/400 atm and beyond. Nobody has done it.

Cabin pressurization might get you to ~50atm, but that's around the extreme limit, so regardless of cabin pressurization the hull has to handle most of it.

Here's hoping it has and they can be found quickly.

Re: Titanic tourist submersible goes missing with search under way

#533

Post by belorn »

narrator wrote: post #427
jhugo wrote: post #377

Earlier quoted context omitted.

> If the actual risk are close to BASE jumping then you’ve failed. The myriad BASE jumping businesses would probably like a word. Risk tolerance varies.

There are things that are even more dangerous than BASE jumping that people do for fun, like cave diving, but people do them. I never got the attraction of people to cave diving. All you have to do is kick up a little dirt, and you're pretty much dead.

A generalization that I often hear for open water diving is that the drive to a dive place is more dangerous than diving itself, at least considering the time spent on the highway compared to the much shorter duration that is the dive.

That said, it does require a lot of training and certification, and people need to maintain that training and their gear. It not so much that kicking up a little dirt will kill you (it generally won't), but that a combination of complacency, stress and panic will kill you. In that it is again similar to driving in that in generally it is not the car or even the highway speeds that kills people, but rather complacency and a lack of attention to the road and traffic. Random tire explosion on the highway is a real risk, but even that is usually a lack of attention to maintenance.

Re: Titanic tourist submersible goes missing with search under way

#534

Post by eggy »

jskrablin wrote: post #505
zarzavat wrote: post #490

Earlier quoted context omitted.

Honest question, why do it? What’s the attraction of cave diving? Are underwater caves exciting enough that it’s worth the risk? Or is the risk itself the main thrill? Or is your perception that it’s not that risky? I can understand the attraction of e.g. wingsuits, because the idea of flying like a bird is compelling, even if I would never risk my own life to do it. Although there’s definitely more than a few wingsu…

Adrenaline is a powerful drug. And there's also a 100% focus (or very close to it), something that's really hard to achieve otherwise. Keeping yourself fit counts as well. I don't cave dive but I do ride MX which is also considered a risky sport. I'd say you'll hear similar answers from everyone dealing with risky sports/activities.

Surprisingly there are skilled but unfit cave divers. You are neutrally buoyant most of the time with little need for major physical exertion. I was a technical driver for over 6 years. The more efficient you become the less energy and air you use. I like to parachute and motorcycle too. I am a certified rope technician (SPRAT) and that takes the most physical exertion of the bunch for me, but that gets better with skill too. Gravity, the plane and the moto do most of the work for the others. That's why I go to a boxing gym for fitness among other activities.

Re: Titanic tourist submersible goes missing with search under way

#535

Post by venusenvy47 »

boppo1 wrote: post #370
carbine wrote: post #345

Earlier quoted context omitted.

According to David Pogue (journo who did a dive on this vessel last year), at least as of last year there was no beacon to transmit location. One would hope radio would be working, in that case. Source: https://twitter.com/Pogue/status/1670826522138091521?s=20

>sealed from the outside >no location beacon Wtf is anyone thinking getting in this thing?

And literally steered with a cheap game controller. There's a YouTube video from CBS of their reporter taking a trip on this thing. It's almost comical how cheap it seems.

Re: Titanic tourist submersible goes missing with search under way

#536

Post by venusenvy47 »

accurrent wrote: post #331
paulpauper wrote: post #310

Earlier quoted context omitted.

it should be findable by simple radio/celular contact?

This is under water. Radio/Cell do not penetrate beyond a few centimeters. Communicating underwater is usually done via acoustics.

They have some type of radio link that works at depth for simple texts messages, but they have to be right above it.

Re: Titanic tourist submersible goes missing with search under way

#537

Post by sixQuarks »

jacquesm wrote: post #322
civilitty wrote: post #205

Earlier quoted context omitted.

> At 30,000 ft. a sharp crack rang through the ship, shaking it violently. The water pressure outside was more than 6 tons per sqare inch., and even a slight fracture in the hull would have meant certain death. It proved to be only an outer Plexiglas windowpane which had splintered under the pressure. The inner hull remained watertight. "A pretty hairy, experience," admitted Walsh. https://web.archive.org/web/2007020…

Pretty gutsy to continue after that rather than to go back up and investigate what it was first.

No kidding. I would have insisted on going back up, I admit I'm not cut out for adventure at this scale.

Re: Titanic tourist submersible goes missing with search under way

#538

Post by onetokeoverthe »

carbine wrote: post #111

I'm hesitant to speculate but just sharing -- an earlier version of this submersible was scrapped: "OceanGate will take advantage of lessons learned during the construction of its carbon-hulled Titan submersible, which was originally built for Titanic journeys. Rush said tests that were conducted at the Deep Ocean Test Facility in Annapolis, Md., revealed that the Titan’s hull “showed signs of cyclic fatigue.” As a r…

[dead]

Re: Titanic tourist submersible goes missing with search under way

#540

Post by dtagames »

dtagames wrote: post #26
mongol wrote: post #5

I had no idea that "tourists" visited Titanic. Is this the new thing after Everest became crowded?

[flagged]

Fresh quote from the CEO this morning:

  Rush also said during the interview, "You know, at some point, safety just is pure waste. I mean, if you just want to be safe, don’t get out of bed."

 "Don’t get in your car. Don’t do anything," he added. "At some point, you’re going to take some risk, and it really is a risk/reward question. I think I can do this just as safely by breaking the rules."[0]
[0] https://www.foxnews.com/world/oceangate-ceo-last-year-addres...
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