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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

#312
post #67
post #61

Earlier quoted context omitted.

> 13,000 ft titanic is at about 12500, according to wkikipedia - a bit close?

Not really. Numbers like that have some safety margin built in.

Time will tell on that one.

Re: Titanic tourist submersible goes missing with search under way

#313
post #53

Earlier quoted context omitted.

A location pinger would be a no brainer but like you say, it only helps if there's another sub with a grapple in range, in time. I understand why oceanographers /might/ want to do this, but not in person when ROV tech is so good now, for biology and tourism. There are so many things that can happen to fragile humans in that complex machine: drowning, freezing, asphyxiating, crushing, oxygen narcosis, nitrogen narcosi…

> So why do people risk all that, and pay 125k to do it? People enjoy casual risk-taking. If I had the 125k to dish out for this experience, I probably would have done so myself.

Lucky you, then.

Re: Titanic tourist submersible goes missing with search under way

#314

Earlier quoted context omitted.

Is there some sort of underwater "GPS" tracker they can use to track the sub?

Communicating with submarines is actually a nightmare. The saltwater ruins most radio communications, so you have no chance to receive GPS signals, which are pretty weak even on the surface. One thing the military does/did to communicate with subs is use low-bandwidth text-only very low frequency radio, but you need colossal transmitters and there's no way the mother ship carries one. Hydrophones are also an option,…

Military submarines also have a towed communications buoy that they can use to communicate with satellites. But that thing is connected to the submersible via a cable.

Re: Titanic tourist submersible goes missing with search under way

#315

Skimming the website, I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost, the weights drop off and the submersible floats up to the surface again? And 96 hours of life support sounds good, but unless there is another submersible nearby that can dive down, find them AND attach a line, the number of hours of life support will be irrelevant. Of c…

> I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost I don't think they have any "drop-weights" which would make them positively buoyant. If I'm reading the spec-sheet correctly, the submersible itself weights ~1500lbs. Subs have ballast tanks which they pump with air and force out water to make themselves positively buoyant. But if something…

There are typically compressed air cylinders that can expel the water in case of emergency. At least on military submarines that go down to 300m, it may not work 4km down where the pressure is ridiculous.

https://en.wikipedia.org/wiki/Emergency_main_ballast_tank_bl...

Re: Titanic tourist submersible goes missing with search under way

#316
post #158

Earlier quoted context omitted.

As someone with a surname that is easily made fun of, I urge you to just leave off irrelevant quips.

Nomen est omen is a saying since the Roman times, and there are scientific studies that show names do have an effect on professions (eg there are more people named Art working with Art than youd statistically expect)

In that case, poor Bickus Dickus

Re: Titanic tourist submersible goes missing with search under way

#317
post #238

Earlier quoted context omitted.

What's the matter with that?

It is a submarine that carries people to depth. I don’t think it should have consumer-grade lighting designed for an RV that has windows and an exit that is always possible to use. It should not have a low-cost consumer-grade controller. The CEO should not be bragging about the fact that it does, on camera. It demonstrates an incredible lack of experience and/or mental disconnect. All of this would be fine if it were…

Apparently he's on the sub. That is probably the one place where he could be that he won't end up being sued out of existence for gross negligence.

Re: Titanic tourist submersible goes missing with search under way

#318
post #280

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I've had some work in designing vessels to take external pressure. It's fundamentally a nonlinear problem. A lot of new(and some not so new) engineers don't understand the process of solving it properly For instance, euler buckling is the simple eigenvalue problem of solving a column in compression. But, it misses: initial defect because nothing is truly straight, material nonlinear effects if the part approaches yie…

That’s sounds crazy complicated. In engineering is it like software design where you can get very far just being bad? Like do companies hire just crap engineers who don’t know all this stuff and call it a day? (Kind of like hiring offshore to build mvp for cheapiest crappiest quality possible)

You can do that but you'll spend a lot of money breaking things. If you're in a non-safety critical field then that is a possibility. But, you really need good engineers, or to make them through these mistakes, to figure out what is really going wrong.

Re: Titanic tourist submersible goes missing with search under way

#319
post #259

Earlier quoted context omitted.

The hatch is bolted shut from the outside. When you make it back to the surface, there is no way to get out without external support. If the mother ship can not find the sub the occupants could be trapped bobbing just below the surface until their air runs out.

Could they just have some drills with diamond-tipped bits stored inside for emergency use? If needed, drill through the whole shell, stick an arm out and unbolt from the outside. Or maybe a jackhammer to just hammer through whatever glass is there for observation purposes.

> Or maybe a jackhammer to just hammer through whatever glass is there for observation purposes.

I'm now wondering if a jackhammer applies more force than the ocean at titanic depths. I suppose less uniform force at least.

Re: Titanic tourist submersible goes missing with search under way

#320
post #233
post #129

Earlier quoted context omitted.

That's how you bring several kW of power down to an ROV. An umbilical cable, copper conductors and fiber optics inside steel wire sheath. The weight of the thing makes it impossible to attach it directly to the ROV - It would be unmaneuverable - so instead they bring it down to a TMS (Tether Management System) - basically a cage where the steel umbilical terminates and a spool of lightweight tether cable, 100m or so,…

This is great info! Can you please point me to any write up that explains this in more details?

There are several companies specializing in deep see ROV applications, it's a super interesting field.

https://en.wikipedia.org/wiki/Remotely_operated_underwater_v...

Is a great starting spot, read it and then branch out following the sources links.

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