from Hacker News

Titanic tourist submersible goes missing with search under way

by lode on 6/19/23, 1:48 PM with 609 comments

• by carbine on 6/19/23, 6:46 PM

  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 result, the hull’s depth rating was reduced to 3,000 meters.

  “Not enough to get to the Titanic,” Rush said."

  Source: https://www.geekwire.com/2020/oceangate-raises-18m-build-big...

• by scarnz on 6/19/23, 3:46 PM

  This appears to be the vessel in question:

  https://oceangate.com/our-subs/titan-submersible.html

  Pressure hull made from titanium and carbon fiber, capable of diving to 4000m (13,000 ft).

  I recall that one reason SpaceX switched from carbon fiber to stainless steel pressure vessels (fuel tanks) was the difficulty of detecting structural flaws.

  Can any engineers comment on whether that task is easier for a vessel exposed to compression (under sea) as opposed to vacuum (space)?

  How likely is a catastropic failure due to undetected flaws in carbon or composite (carbon + Ti) structures like these?

• by ralphhughes on 6/19/23, 4:07 PM

  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 course if the pressure hull has failed catastrophically it will have been over mercifully quickly. Anyone know if deep-diving submersibles are required to carry black-boxes like aircraft?

• by dangle1 on 6/19/23, 9:01 PM

  Few more details from The Seattle Times:

  >David Concannon, an adviser to the company, said Oceangate lost contact with the sub Sunday morning. It had a 96-hour oxygen supply, he said in an email to The Associated Press on Monday afternoon. “Now 32 hours since sub left surface,” said Concannon, who said he was supposed to be on the dive but could not go due to another client matter. He said officials are working to get a remotely operated vehicle that can reach a depth of 6,000 meters (about 20,000 feet) to the site as soon as possible.

  https://www.seattletimes.com/nation-world/nation/a-search-is...

• by rajnathani on 6/19/23, 5:19 PM

  For those mentioning about detailed location tracking / communication: Non-low-bandwidth communication underwater is really difficult due to the physics of EM waves traveling through a medium such as water: https://en.m.wikipedia.org/wiki/Underwater_acoustic_communic...

• by Animats on 6/20/23, 4:46 AM

  Twitter video of vessel.[1] Not encouraging.

  [1] https://twitter.com/FnpMarieOH/status/1670931677013524487

• by bell-cot on 6/19/23, 4:32 PM

  Not an expert...but my impression is that the implosion, at depth, of even the very small submarine in question here would generate an extremely loud "noise". Probably obvious to any hydrophone on the support vessel, and near-certainly recorded in detail by military monitoring systems.

• by ciguy on 6/19/23, 6:24 PM

  This section from their website is interesting:

  "Real-Time Health Monitoring The most significant innovation is the proprietary real-time hull health monitoring (RTM) system. Titan is the only manned submersible to employ an integrated real-time health monitoring system. Utilizing co-located acoustic sensors and strain gauges throughout the pressure boundary, the RTM system makes it possible to analyze the effects of changing pressure on the vessel as the submersible dives deeper, and accurately assess the integrity of the structure. This onboard health analysis monitoring system provides early warning detection for the pilot with enough time to arrest the descent and safely return to surface."

  I am surprised that real time monitoring of the hull is even a consideration, I would have expected it to be designed an built with massive safety margins and then inspected very thoroughly after each trip. The above paragraph seems to indicate that they would monitor hull health during the trip and stop descent if it showed signs of stress. But I am skeptical that they would see signs of stress before it simply imploded at depth.

• by rodface on 6/19/23, 4:05 PM

  It's worth contrasting the design of this vehicle with what is ostensibly the world standard for deep-sea research submersibles, Alvin of Woods Hole Oceanographic Institution.

  https://www.whoi.edu/what-we-do/explore/underwater-vehicles/...

• by BXLE_1-1-BitIs1 on 6/19/23, 5:19 PM

  Hydrophones will pick up a crush event. When the Scorpion went missing, they eventually found spikes in the recordings and were able to triangulate.

• by jugg1es on 6/19/23, 4:54 PM

  They just had a story on this on CBS Sunday Morning. A reporter actually went down in the sub but it got called off mid-dive. He had to go back later. It didn't seem safe.

• by WalterBright on 6/20/23, 2:14 AM

  I'm surprised the craft doesn't have a pinger, like airplane black boxes do (and those can survive on the ocean floor, too). 96 hours of oxygen won't help if it takes 200 hours just to find where they are.

• by beowulfey on 6/19/23, 2:38 PM

  Not a lot of information about this one. Does the Coast Guard have a submersible of their own that they could use to recover, even if they were able to find them?

• by iambateman on 6/20/23, 12:58 AM

  I don’t want to make light of the situation in the least.

  But the company responsible is literally named OceanGate.

  Some headlines write themselves.

• by saturn5k on 6/20/23, 7:59 AM

  I don't understand after all these years why there's still this obsession with the Titanic. What keeps fueling its enduring fascination? People spending 1/4 million just to barely see a sunken ship? Bragging rights for the rich?

• by mongol on 6/19/23, 2:48 PM

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

• by shultays on 6/20/23, 11:05 AM

  I feel bad for thinking of this but now there are two wrecks to visit. Even more reasons for tourism!

• by mikeyouse on 6/19/23, 2:41 PM

  A CBS article identified this company’s sub as the one involved;

  https://twitter.com/OceanGateExped

• by meghan_rain on 6/19/23, 11:29 PM

  It's intriguing to see what kind of personality a billionaire has that pushes him to do these stunts and also publicly brag about them. I hope it's not a necessary ingredient to success as I do not intend to live like that.

  That being said,

  > He added that because the passengers were sealed inside the vessel by bolts applied from the outside, "There's no way to escape, even if you rise to the surface by yourself. You cannot get out of the sub without a crew on the outside letting you out."

  ouch

• by Mizoguchi on 6/20/23, 12:54 AM

  How come there's no way to communicate once under water? Wouldn't be possible to launch a tiny probe attached to the exterior of the sub, either manually or automatically when in trouble, sort of a black box, that bounces back to the surface to broadcast crew messages, sub data and location? Seems like an obvious safety device to have. Are there any technical reasons why this is not available on a vehicle with suck poor performance?

• by omginternets on 6/19/23, 4:05 PM

  “The Boston Coast Guard […]”

  As in the American city of Boston? If so, why are they the first responders here?

• by Svetlitski on 6/19/23, 6:08 PM

  I cannot help but think of the novel “A Fall of Moondust” by Arthur C. Clarke.

• by wnc3141 on 6/20/23, 6:07 AM

  After hearing about the experimental nature of the firm (see: https://www.youtube.com/watch?v=29co_Hksk6o&t=203s), does anyone have any perspective on the firm's ethics or responsibilities for unknown dangers? How does this compare to say astronauts or experimental aircraft pilots?

• by 6d6b73 on 6/19/23, 7:02 PM

  The Seastate podcast has a great episode with the founder of Ocean Gate. Worth every minute. https://open.spotify.com/episode/4GivNvcl1L7n9BFnNfVEju

• by MiguelX413 on 6/19/23, 6:29 PM

  Why do they keep emphasizing the fact that the submarine has gone missing and not the people within it?

• by totallywrong on 6/20/23, 12:44 AM

  I get the flex this affords, but I can't think of anything less appealing than spending 8 days underwater in a tiny capsule. I hope they're found and nothing happened.

• by rurban on 6/20/23, 1:13 PM

  Since no parts arrived at the surface yet, they'd need to bring over Jason. Jason already recovered two lost ROV's at 2200m in 2021.

  https://www.hydro-international.com/content/news/rov-jason-h...

• by redroyal on 6/20/23, 3:29 AM

  Maybe it’s time we stopped treating that grave site like a tourist attraction. There is some sour irony here but I hope they are recovered safely

• by stan_kirdey on 6/20/23, 9:32 AM

  i hope they are fine just a bit lost,

  at the same time the irony if the next ship will be giving offering two wreckages for one tours

• by Borrible on 6/20/23, 8:16 AM

  Booking a seat on a floating wreck between Tunisia and Greek would have been much more adventurous. And cheaper.

• by dahwolf on 6/19/23, 9:45 PM

  "Rear Adm Mauger said the rescue teams were "taking this personally" and were doing everything they could to bring those on board "home safe".

  What does that even mean? Is this opposed to your normal non-personal/strictly professional mode where you would not do everything you could?

• by johnnyApplePRNG on 6/19/23, 6:44 PM

  Was it only crew on the submersible or were there paying guests as well?

• by Avlin67 on 6/20/23, 12:46 AM

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

• by dirtyid on 6/20/23, 7:35 PM

  For 250k, I hope they were provided a cyanide pill.