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Debris found came from missing Titan sub, says friend of passengers

bbc.com

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Re: Debris found came from missing Titan sub, says friend of passengers

#91

Post by mym1990 »

danso wrote: post #74
psychphysic wrote: post #43

Earlier quoted context omitted.

I agree but not at 250k a head. It should be safer, but everything is done to a price point and I'm sure those on board recognised the risk of such an expedition.

I seriously doubt the victims knew how risky this trip was, even though they signed the waivers. Why would you bring along your 19-year-old son if you thought the chance of death was 1/100 or even 1/1000. The CEO, who obviously overestimated the safety of his cost-cutting design, had raised $20M in venture capital, it's not as if he had a death wish either.

Might have been the 19 year old's idea, and risk assessment is not a strong point of youth.

Re: Debris found came from missing Titan sub, says friend of passengers

#92

Post by ridgeguy »

can16358p wrote: post #57
mindslight wrote: post #50

Earlier quoted context omitted.

How do submarines commonly fail? Is the assumption of a violent implosion warranted? I would think another failure mode could be water rushing in without the overall structure catastrophically failing, which would actually relieve pressure on the structure as it happened and be much less energetic.

Just note that the body was experimental: while the hull indeed have a thick titanium body, it was mixed with (don't know exactly how and where though) carbon fibers, which are known to catastrophically break under pressure if there's even a microscopic impurity or damage. At least that's what the experts say. Carbon fibers is great for lightweight things that need to bend, terrible for things to be relied under pres…

And composite materials are basically threads embedded in glue. Threads can be extremely strong in tension. In compression, you have only the strength of the glue and the fiber/glue interface strength, which isn't a whole lot. Composite materials are in general poor in compression. Crewed submersible hulls are always in compressive stress from the ocean outside. I can't fathom why somebody would choose a composite for a deep submersible hull. It's just asking for a buckling failure. Bad design choice, IMO.

Re: Debris found came from missing Titan sub, says friend of passengers

#93

Post by mustacheemperor »

ak_111 wrote: post #4
ClassicOrgin wrote: post #2

Based on this it seems pretty likely that it immediately imploded and the ‘banging’ was from the Titanic debris itself.

Why is it more likely that it immediately imploded rather than after a few days? The latter is more probable to me as it has never been tested under water for more than a few hours at a stretch. This will also be consistent with your banging hypothesis which was only heard after a day or two when it got lost. And also with the fact that no immediate sound disturbance was registered with the controlling ship. I of cou…

If the sub imploded after the search had begun, would the search vessels have detected the sound?

Re: Debris found came from missing Titan sub, says friend of passengers

#94

Post by eigenspace »

tivert wrote: post #89

Why has this sub been so hard to find? I keep seeing reports that they've search an area "the size of" Massachusetts or Connecticut. Shouldn't OceanGate have recorded the exact coordinates where it was released and then been able to localize its possible location to a small area around that by modeling ocean currents or something? My understanding the Titan was designed to sink to the bottom and could only move very…

> Shouldn't OceanGate have recorded the exact coordinates where it was released and then been able to localize its possible location to a small area around that by modeling ocean currents or something?

Modelling and knowing surface currents is one thing, but this submersible was thousands of meters deep. Deep ocean currents can be very fast, change often, and we have way less data on them.

Re: Debris found came from missing Titan sub, says friend of passengers

#95

Post by sho_hn »

danso wrote: post #74
psychphysic wrote: post #43

Earlier quoted context omitted.

I agree but not at 250k a head. It should be safer, but everything is done to a price point and I'm sure those on board recognised the risk of such an expedition.

I seriously doubt the victims knew how risky this trip was, even though they signed the waivers. Why would you bring along your 19-year-old son if you thought the chance of death was 1/100 or even 1/1000. The CEO, who obviously overestimated the safety of his cost-cutting design, had raised $20M in venture capital, it's not as if he had a death wish either.

> I seriously doubt the victims knew how risky this trip was

I'm quite curious about this, too. I'm not so sure. I think even if you are not an engineer, it should be quite easy to understand how under-tested this vehicle is compared to, say, a commercial jet airliner, and how much more difficult the application is at the same time. These were business men running companies of some size. It should come with basic work experience to reason about how proven processes or articles are.

I think it's more likely that the threshold for "you know what? let's take our chances" works differently for different people.

For example: I would never get LASIK eye surgery, safety statistic be damned, because the consequences in the unlikely event of failure are too large for me. And yet many other people know the data just as well and make a different call.

Re: Debris found came from missing Titan sub, says friend of passengers

#96

Post by tivert »

https://www.bbc.com/news/live/world-us-canada-65967464?ns_mc...:

> We have just had an update from dive expert David Mearns, who says the debris includes "a landing frame and a rear cover from the submersible".

> Mearns is a friend of passengers aboard the Titan.

> Mearns has told the BBC that the president of the Explorers Club (which is connected to the diving and rescue community), provided this new information.

Re: Debris found came from missing Titan sub, says friend of passengers

#97

Post by sho_hn »

RIMR wrote: post #78
psychphysic wrote: post #36

RIP to these guys, yes it was a risky trip. But it was into international waters and they were AFAIC explorers. Stuff like this can not be done without risk. Hopefully future subs will have more safety features.

>Hopefully future subs will have more safety features. From an engineering standpoint, Titan didn't have any safety features at all. What any sane engineer would recommend as a last-ditch backup system Oceangate relied on as a single-point-of-failure. No phone. No beacon. Budget bluetooth controller and touchscreens. Electronics you'd expect to find in an RV. All from a CEO who flaunted his corner-cutting and apathy…

> From an engineering standpoint, Titan didn't have any safety features at all.

This isn't quite true. It had multiple redundant ways to drop ballast, for example.

What I would say from what I was able to find out (and with some familiarity of safety engineering processes from work; I make cars) is that it's safety-concept was very spotty. It had solutions to some problems, but also large gaps in the safety concept. Safety was not addressed in holistic fashion.

It's interesting to compare this with solutions found in other subs. For example, Titan had four different ways to drop ballast, but from the list I saw, all of them required manual intervention by a non-incapacitated crew and electronics to be working.

On Cameron's Deepsea Challenger--by another rich guy who funded a vanity dive, and relying on homebrew innovations in material science--ballast was held by corrosible wire that would be corroded by seawater in a set time, so the sub would eventually surface automatically. Ballast drop was also triggerable remotely by an acoustic signal, more reliable than radio. The available info is pretty bad, but Titan may not have had those solutions in place.

I'm very much out of my depth (no pun intended) on naval/submarine engineering, and I'm hoping for someone with better knowledge to extend that comparison somewhere.

Re: Debris found came from missing Titan sub, says friend of passengers

#98

Post by TT-392 »

RIMR wrote: post #78
psychphysic wrote: post #36

RIP to these guys, yes it was a risky trip. But it was into international waters and they were AFAIC explorers. Stuff like this can not be done without risk. Hopefully future subs will have more safety features.

>Hopefully future subs will have more safety features. From an engineering standpoint, Titan didn't have any safety features at all. What any sane engineer would recommend as a last-ditch backup system Oceangate relied on as a single-point-of-failure. No phone. No beacon. Budget bluetooth controller and touchscreens. Electronics you'd expect to find in an RV. All from a CEO who flaunted his corner-cutting and apathy…

You can't just have a phone that works at those depths

Re: Debris found came from missing Titan sub, says friend of passengers

#99

Post by somenameforme »

tivert wrote: post #89

Why has this sub been so hard to find? I keep seeing reports that they've search an area "the size of" Massachusetts or Connecticut. Shouldn't OceanGate have recorded the exact coordinates where it was released and then been able to localize its possible location to a small area around that by modeling ocean currents or something? My understanding the Titan was designed to sink to the bottom and could only move very…

This is something I'd also like to know.

I'd assume they were assuming a worst case scenario of something like a ballast malfunction paired with a propulsion malfunction, so you have a partially buoyant (enough to stay off the ground, not enough to surface) craft being pushed both by currents, and possibly its own propulsion, in an unknown direction in some radius outside of the Titanic. I've no idea of the depth sonar can accurately ping, so they may also have been considering the 3-d area around the Titanic in which case you're hitting radius cubed, and so even a "small" max distance could be huge.

Re: Debris found came from missing Titan sub, says friend of passengers

#100

Post by uejfiweun »

tivert wrote: post #96

https://www.bbc.com/news/live/world-us-canada-65967464?ns_mc... : > We have just had an update from dive expert David Mearns, who says the debris includes "a landing frame and a rear cover from the submersible". > Mearns is a friend of passengers aboard the Titan. > Mearns has told the BBC that the president of the Explorers Club (which is connected to the diving and rescue community), provided this new information.

Oof. Well, that's the end of this. At least this means they had a quick death. I read that a submarine implosion would actually happen faster than your brain would be able to register that anything is even happening.
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