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Titanic tourist submersible goes missing with search under way

bbc.com

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Re: Titanic tourist submersible goes missing with search under way

#511

Post by tim333 »

belorn wrote: post #367
mechhacker wrote: post #254

Earlier quoted context omitted.

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…

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.

Re: Titanic tourist submersible goes missing with search under way

#512

Post by beowulfey »

krisoft wrote: post #476
gremlinunderway wrote: post #230

Earlier quoted context omitted.

> As opposed to the professionals who went with a microsoft xbox controller? I think what's more telling is that they didn't even splurge on the actual Microsoft Xbox controller. They cheaped out with an unproven logitech gamepad. When you're already doing something in an unorthodox way at least don't half-ass it. > The company in question might be full of jokers, but your points don’t quite illistrate this well. The…

> Your distinction is a bit arbitrary. Every point about this company will always be about appearances unless you have first-hand accounts or experiences. Not really. Here is a substance based argument: there is no underwater FAA. This company, and any other private submarine company is setting their own quality level and then marking their own homework to see if they have met it. In a commercial environment they are…

I think this is the big thing for me. David Pogue, when he went on a dive with them last year, pointed out that the vessel has no beacon [1]; yet the door bolts from the outside. Apparently there was a five-hour period where the company did not know the location of the sub after it resurfaced.

To me, that seems crazy. Having a GPS beacon seems like a no-brainer for safety purposes. It feels indicative of the engineering as a whole.

[1]: https://twitter.com/Pogue/status/1670826522138091521

Re: Titanic tourist submersible goes missing with search under way

#513

Post by Jarmsy »

wnevets wrote: post #159
spatialaustin wrote: post #157

Earlier quoted context omitted.

David Pogue, who traveled to the Titanic with OceanGate last summer, has said that he was on the control ship when a previous sub was "lost for about 5 hours". Source: https://twitter.com/Pogue/status/1670835763536183297

> and they shut off the ship’s internet to prevent us from tweeting. Some how that makes it even worse.

And the author is revealing this only now!? That's not a great look, being witness to massive safety violations and keeping quiet about it until after it goes wrong.

Re: Titanic tourist submersible goes missing with search under way

#515

Post by wnkrshm »

GolfPopper wrote: post #168
mcpackieh wrote: post #60

Earlier quoted context omitted.

TBH at this stage we just don't know. They might not have imploded but instead been left stranded on the bottom with an intact pressure hull but some other sort of equipment failure. Still a hopeless situation unfortunately.

Best case outcome at this point seems like it would be that they're on the surface, off target, with a complete communications failure. I hope that or something similar is the case, but the odds seem low.

Even then it's horrible, since the thing is sealed from the outside (as basically all crewed DSVs are)

Re: Titanic tourist submersible goes missing with search under way

#516

Post by reddit_refugee3 »

Retric wrote: post #372
jhugo wrote: post #365

Earlier quoted context omitted.

It's always safety vs. money. A risk-free submersible or spacecraft does not exist. It's always possible to spend more money to further reduce the risks, but naturally with diminishing returns. At some point, you have to decide to accept (very small) risks in order to avoid (very large) additional costs.

People are perfectly happy to accept some risk. However you can’t expect normal people to take on extreme risk and expect a profitable long term business. If the actual risk are close to BASE jumping then you’ve failed.

It also isn't reasonable to expect "normal people" to be experts on every single thing so that they even realize they are taking an extreme risk in the first place.

Re: Titanic tourist submersible goes missing with search under way

#517

Post by beowulfey »

aaron695 wrote: post #156
wnevets wrote: post #145

Earlier quoted context omitted.

unfortunately this sounds like "move fast and break things" in the worst possible way.

It gets boring hearing people who can't program or manage blurt out 'move fast and break things' whenever they hear of failure. Learn to code. Or if you're not smart enough learn project management. Alternatively stop using sayings in other peoples fields. Do something dumb like journalism.

Is this a bot? What a strange thing to say in a thread about submersibles.

Re: Titanic tourist submersible goes missing with search under way

#518

Post by fullstop »

krisoft wrote: post #469
fullstop wrote: post #290

Earlier quoted context omitted.

> As opposed to the professionals who went with a microsoft xbox controller? [1] The Xbox controllers have an astronomical number of testing hours on them by now.

Can’t you say the same thing about the logitech one? My point is that using an off the shelf solution is not necessarily a bad one. Probably there are differences between the reliability of the different controllers within that category but not to the level where choosing one over the other is a clear sign of engineering mallpractice.

There are far more Xbox controllers in use than Logitech. In the gaming community, the Logitech controllers are known to be janky and less reliable.

The PlayStation controllers are more popular globally, but have not had a great track record when it comes to operation with anything but a PlayStation.

I get what you're saying, though, and I'm not faulting them for using an off-the-shelf product. I'm faulting them for using a substandard product.

Re: Titanic tourist submersible goes missing with search under way

#519

Post by beowulfey »

tazjin wrote: post #214
lode wrote: post #85

Earlier quoted context omitted.

David Pogue went down with the same vessel last year for CBS: https://www.youtube.com/watch?v=29co_Hksk6o "I couldn't help noticing how many pieces of the sub seemed... improvised."

This video strikes me like a TV clip from a more civilised era or something. It's calm, there's no annoying music, the initial presenter didn't say anything too clickbaity. It's oddly calming.

CBS also does 60 minutes, which I've also long respected for a similar kind of calm, collected vibe for journalism.

Re: Titanic tourist submersible goes missing with search under way

#520

Post by svnt »

swader999 wrote: post #408
londons_explore wrote: post #134

Earlier quoted context omitted.

So it's possible this sub is stuck turning in right only circles deep underwater because the left button has broken...

They would just drive upside down for a bit.

I mean that’s good lateral thinking but the issue is not that one particular button will go out but that any button or buttons could, and at any time, and it would probably be the most-used buttons since it was wear-based failure.

They also briefly showed a single button on the wall that it was implied functioned like an elevator button.

There were a lot of ways it looked like things could trivially go wrong, once you got a feel for how it was built.

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