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Comment by mcpackieh | Hacker News Reader

> According to the court documents, in a 2018 case, OceanGate employee David Lochridge, a submersible pilot, voiced concerns about the safety of the sub.

2018; this would make it the previous model, no? Not the same submarine that went missing. At least that's the impression I get from this article (2020): https://www.geekwire.com/2020/oceangate-raises-18m-build-big...

> "That meant the Titanic trips — which had been planned at first for 2018, then 2019, then 2020 — had to be put off until mid-2021. By that time, Rush expects the new submersibles to be ready to enter service."

It's my impression that one of those "new submersibles" is the one that's lost.

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Even if that is the case, the ethos of the company was to dismiss safety concerns, use inappropriate hardware, stonewall and then fire the only person who cared.

People died. I do hope the CEO isn't one of them, because he needs to be thrown in front of a court. Same with the other senior executives and HR.

no one died yet...

They could all easily already be dead. We simply don't know.

If indeed that viewport collapsed at 4000m as the article suggests, they probably didn't even have time to realize they were dying.

Relatively, exceedingly merciful.

How long would it take to get down to 4000m though, didnt they lose contact like 1 hour in?

The ascent and descent to Titanic is about 2 hours one-way. The exact time they say they lost contact was after around 1 hour and 45 minutes. It was likely at or close to at the depth of Titanic.

The article says they were going for 4000m, but it was only rated for 1300m.

That would imply a collapsing somewhere between the two.

Also, would the body, being mostly made of water itself, really get crushed instantly? I would certainly expect the pressure to squeeze all the air out of your lungs.

I know nothing about how the body behaves under high pressure.

I looked up a depth to pressure calculator, at even 1300m, the pressure is 1892.67 psi.

"psi" is pounds per square inch, and a human has ballpark 3000 square inches of surface area.

So to get a (very) rough approximation, picture what would happen if you squeezed a human with 3000*1892 pounds of force. Or try not to picture it, because I imagine it being pretty gross.

MythBusters did this with a realistic (pig?) manikin. Pretty gross, yes.

For anyone that would want to see that: ‘Mythbusters - Compressed diver’ https://youtu.be/LEY3fN4N3D8

Yeah. Reminds me of this underwater pressure awareness training video on youtube from a few years ago: https://www.youtube.com/watch?v=PXgKxWlTt8A (if you're squeemish, don't click that link)

Industrial divers / welders / etc get all kinds of training to avoid that stuff, for good reason.

I'm sure they never imagined this video being paired with an incident like this but wow, their joyful and excited reactions (with no context of the lead up to this experiment) feels really morbid/sick. I realize they were trying to prove a myth and it worked, but still found it unsettling.

You'd have to subtract about 1atm from that, but yes the sudden pressure change would be quite gross.

That said, if divers are slowly "eased in" to the high pressure environment, it is actually possible to equalize pressure slowly and acclimatize. Though 1.3km would still likely be beyond the limits of that https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5110125/

The watery bits of the body would be ok but the airspaces like the lungs would rapidly compress to almost nothing.

https://m.youtube.com/watch?v=LEY3fN4N3D8&feature=youtu.be&s...

I'm Hollywooding it here, but I bet it develops crack lines before collapsing. Most things in nature fail slowly, then all at once - think of standing on an iced-over puddle or pulling tree limbs.

I think 400 atmospheres of pressure change the dynamics a lot here.

Perhaps there might be a hairline crack that makes a window shatter when it's hit with a hammer. Except the hammer impact is constant. I don't think there would have been a lot of time.

I don't mean that it had a crack in it, but that it developed one as a precursor to total failure. My experience of physical materials is that they almost never just atomize, rather there's a weakpoint from which the failure cascades. I'm envisioning a process that might only last a few seconds, or be measurable in milliseconds.

The forces are immense and act all the time. In your daily life, you don't usually have that kind of system, so this feels counterintuitive.

Press against a solid object gently with one hand on each side, then suddenly yank away one hand. The object will be accelerated gently. Now do that with all your strength and send the object flying through the room in no time, with a few dozen kg of pressure. Now imagine that you could apply hundreds of tons of pressure. In such a system, every change will be nigh instantaneous.

I understand the physics just fine, thanks. I'm not disputing that it will be 'nigh instantaneous', I'm talking about how it fails. You and downvoters are also neglecting the fact that the submersible isn't suddenly teleported to/near its destination at which point it suddenly fails. It gets there slowly, passing through its safety envelope on the way.

This is likely less the case when the pressure differential is ~480 bar.

Failure is going to occur on the order of fractions of a second at those huge pressures. (Fortunately?)

Here's a pressure vessel failing at only 1 bar:

https://youtu.be/Zz95_VvTxZM

Agreed on the likely short timescale. I am imagining having just enough time to think 'something's not right...' Musicians are sensitive to latencies on the order of 10-20 milliseconds; I doubt there was time for a conversation about it.

Oxygen is just about running out in the next few hours, they don't seem to have had any sonar contact, no cable or underwater phone. Getting something like a DSRV (which wouldn't really help if they are at ground level there, because it cannot dive that deep) there will take at least a day. Even if they are still alive, their chances of rescue are nonexistent.

> Oxygen is just about running out in the next few hours,

Official reports have been saying 40 hours a few hours ago.

Yes there were oxygen scrubbers on-board that had an estimated endurance to provide clean air for about 5 days for 5 people.

It has come out that it is wildly untested and optimistic estimate. The longest mission they had conducted onboard was 12 hours. So the theoretical limit may not be realistic. If there was panic onboard, that would increase oxygen usage dramatically, which could cut as much as 25% off the estimate (which is nearly a day in this case).

In other words... it is grim.

Nitpick: it's CO2 scrubbers, not O2. A scrubber primary mission is to absorb CO2, not generate O2.

So they will peacefully fall into sleep due to hypoxia instead of a slowly rising sense of impending doom as would result from rising C02 levels.

The best 'find things on the bottom of the ocean' gear is usually on a ship somewhere, but just happens to be in-between ships, but is on the Jersey islands in the English Channel. Except it still needs a military cargo plane to retrieve it, deliver it to Newfoundland and be moved by ship on location.

Time isn't on their side.

Yeah at this point, it seems that catastrophe struck 90 mins or so into the dive. That is when contact was lost.

They were early enough into the dive that they would have abandoned the dive after losing contact, they would have only been about halfway to the bottom, and they still would need communication to even find the titanic. So if they lost contact, the mission would have been aborted inside the sub, because they wouldn't have any hope of completing the mission without the aid of the surface vessel.

There are several emergency surfacing options available on the sub in addition to the primary propulsion method. If the sub lost contact, it would have surfaced. That is what happened in several other missions this company has made where communication was lost.

So the fact that communication was lost and no attempt to surface was made, suggests that there was a catastrophic failure. At the pressure they were at, the smallest leak would lead to immediate implosion. The most likely scenario is that they experienced a crack or defect in the hull that lead to implosion. It was likely over before anyone onboard even was aware of a problem (or within seconds of it).

What “mission”? There’s no mission here. These were people with more money than sense going sightseeing where they have no business being.

Mission is a perfectly valid word for describing an outing of a submarine, specially when most of the discussion is surrounding the technical aspects of it. Do you also get angry when a business describes something as mission critical?

> Do you also get angry when a business describes something as mission critical?

Not if they are doing something useful to others.

Are hikers who get lost on a mission?

mission [1]:

    (1) a specific task with which a person or a group is charged
    (2) a definite military, *naval*, or aerospace task

So in answer to your question, yes. If hikers wanted to call their hike a mission it is well within their rights. Merriam-Webster isn’t going to stop them.

You should seriously find better things to do with your life than obtuse rebellion against dictionary definitions. It makes you look like an illiterate nonce.

[1] https://www.merriam-webster.com/dictionary/mission

You're the one who cited the dictionary.

You complained about diction. I cited a dictionary.

It's actually really common in the outdoor recreation world to refer to an outing of some sort as a mission.

I refer to a trip to the grocery store as a mission sometimes

Yes, this is not an uncommon usage of the word.

Sadly puffery and euphemism are all too common.

Implosion is probably the second best possible outcome after being rescued. The alternative of slowly running out of oxygen in 96hrs with no possibility to self-rescue is a level of grueling horror no one should experience.

Implosion should hit sensors though. Maybe they just took on water and drowned.

How likely is it that they actually have survaced but nobody found them yet? Would sonar pick them up if their engines are out? How likely is a visual contact on the ocean if the sub drifted a few miles?

Under water, sonar could pick them up, but sonar is mostly "look down". If a current dragged them somewhere outside the immediate vicinity, they'll be hard to find, because the search vessel needs to be within at most 4km to find them in the water if they are drifting. Far less on the ground, because eliminating and processing ground echos is extremely hard.

If they are on the surface, getting them by sonar is not possible, but aerial surveillance might find them. However, things are very hard to see in the ocean if there are waves. They might have an AIS locator which would transmit their position and an emergency signal, but maybe they skimped on that too, because the submarine-rated ones are expensive.

Shouldn't a sudden implosion be easily detected by hydroacoustic buoys? When submarine ARA San Juan collapsed underwater its sound was detected.

Maybe. Sound travels longer distances in water than in air, but there still is a limit. And hydrophone chains and buoys are probably not dense enough to hear everything.

Volume is also an issue, the Titan is far smaller than a military sub, so the sonar spike corresponding to the implosion will be shorter and of a smaller amplitude.

The sonar on their surface vessel should have picked up the noise, if they have one that does recordings and passive mode. But I guess they were too cheap for that as well, since no regular sonar surveilance of the sub is mentioned in the press.

Well, it's schrodinger's submersible at this point.

Talk about a collapsing wave function! (Or don't)

Prevent the collapse of the wave function to prevent the possibility that the occupants are dead.

Well, they're lost at sea until found if I'm not mistaken.

If the viewing window collapsed then they would have been pretty much instantly compressed to a paste.

Yeah, everyone calculating oxygen rates is a nice optimistic view on the situation.

I think occams razor suggests that they experienced a breach or defect in the viewing window (or possibly the hull).

At the pressures they were at, it would have been over for them, before they ever even knew there was a problem. The pressures are so great, that they would have assimilated into the water instantly.

For what its worth, as sad as that sounds, it is possibly a better fate than the alternative of suffocating to death for 4 days in complete darkness (which is exactly what happened to 23 crew members aboard the Kursk russian sub back in 2000 [1])

[1] https://en.wikipedia.org/wiki/Kursk_submarine_disaster

I also thought they suffocated but it seems more likely that they died in a fire.

"Analysts concluded that 23 sailors took refuge in the small ninth compartment and survived for more than six hours. When oxygen ran low, they attempted to replace a potassium superoxide chemical oxygen cartridge, but it fell into the oily sea water and exploded on contact. The resulting fire killed several crew members and triggered a flash fire that consumed the remaining oxygen, suffocating the remaining survivors."

Apparently they were trying to fix the cartridge and the officer lost control of it and was killed instantly, some of the others dove under the water and survived the fire, but as the fire had consumed all the oxygen, it didn't matter. How they figured all that out from what they hauled up, I can only imagine.

Now all dead. Apparently on the way down.

Everybody was already dead.

I was also curious about the timeline of this. I'm waiting for that one geeky blog post that integrates all the facts.

I'm particularly interested in an educated perspective on their choice in materials. I'm familiar with carbon fibre from bike frame building, and the common tricks/practices to try and look for fissures, find voids/delaminations, etc. after a crash, and it's such a complex subject and material. I wonder who manufactured this vessel and what the quality of their facilities, tools, processes was.

I wonder if the NTSB will do a report on this.

It's also the only planned trip for the company this year due to weather. So the sub has sat for a period of time before being put in use.

Do you think they do extensive trial runs first at the beginning of each season? Like send it to the bottom un-manned just to double check?

As my former boss liked to say "Things that aren't tested don't work."

I think they can't even send it un-manned because it is not externally controllable. From what I understood in footage of a previous "mission", all is operated on board and there is nothing the ship crew can do appart from communicating (when it still works).

...well... Then clearly they should have put more time into the control system to allow for remote control from a submerged audio relay?

We've got more than enough ways to rig up signalling networks that there is zero reason for any submersible to not be remotely tested to crush depth.

My educated (a little bit of engineering at uni) perspective is: Completely idiotic to build a submarine out of carbon and not have the means for a complete inspection for manufacturing defects as the original article suggests.

Carbon, as you correctly note, needs to be very homogeneous. Bubbles, lamination defects or -god beware- fissures lead to failure, of the sudden, unannounced and total kind. And not only is it necessary to check after production, but also after regular short intervals of use, because a mere scratch in the carbon can be fatal.

It seems utterly bizarre to make a sub out of carbon fiber.

The advantage of CF is low weight. But who cares what a submarine weighs?

Some of the articles about it's construction indicate that many of the engineers were aerospace engineers.

I wouldn't want a submarine engineer designing a plane, and vice versa.

I was thinking about that but a steel sub can only really weigh as much as the same volume of water which probably limits things if you are going to 4000m. Too much weight and it'd sink like a stone.

> The advantage of CF is low weight. But who cares what a submarine weighs?

The heavier a sub is the bigger the ballast tanks have to be to compensate and the more energy is wasted on moving it, just like any other powered vehicle.

Do they even have ballast tanks? I saw mention of steel ballast they drop at the bottom.

The biggest benefit of reduced weight on this thing would be minimizing the size of the crane and surface vessel needed to deploy and recover it.

It's very bizarre. It's the first thing you learn about in materials engineering, in any mechanical/aeronautical engineering degree. We even made our own carbon fibre models (some with intentional defects) and tested failing them at my Uni.

I even get worried about cracks in my road bike. These guys are going 3km+ under water... It's insane.

I expect there will be a lot of books documenting every angle of this incident, if for no other reason than because of the Titanic connection. I'm looking forward to reading the whole story on how this incident happened.

https://www.youtube.com/watch?v=4dka29FSZac

Here is a quick and dirty analysis from a US Submariner of 20 years.

It is supposedly, incredibly hard to find defects or damage on carbon fiber. SpaceX did cite this as a reason for using stainless steel. His belief is that there was a hull failure somewhere on the carbon fiber hull; a failure point that simply wasn't found before this dive.

It depends on the material system they used. It is possible to scan for defects just need expensive equipment. Loading and unloading a sub like this could easily result in damages that aren’t detected though

They don't advertise any of their "new submersibles" on the website and the specifications they claim for Titan don't match any of their new submersibles; Titan is rated to go to the Titanic and not any lower. Titan isn't a previous version either. Unless they shelved the first Titan they probably just added some strengthening and called it a day.

I'm blown away that for a sub of that size and shape they used carbon fiber. The sub is positively gigantic and a cylinder is very susceptible to failure after repeated cycles. I'm pretty sure the claims they made about working with NASA and having a system to monitor the structural integrity of the sub are just BS.

"working with NASA"...

"Hi Bob, did you used to work at NASA in the 60's? Can I ask, do you think this 1/100th scale submarine could get to this 1/100th scale titanic in my bathtub? kthxbye"

They found that their previous design with the same materials would get crushed at 2000m. And now this sub disappeared during descent…

The article talks about how this was to do with their 1/3 scale model. I guess the relevant question then is if the "new model" is just the old 1/3 model scaled up, or if there are important differences. Are they still using a viewport that's not certified for the depths they're reaching? Are they still using flammable materials? Are there still parts in danger of de-laminating? Do they still have a culture and pattern of covering up and lying about safety?

If there were relevant changes to the new model other than scaling it up, it'd need to go through a much lengthier certification and testing phase.

That may be true but it still speaks to the company culture.

Based on the Wikipedia page, it _seems_ to be the same one? https://en.wikipedia.org/wiki/OceanGate,_Inc.#Titan_(4000_me...

It took a while to go from dismissing employee concerns to tourism, but it seems to be the same device.

This doesn't tell us whether new submersibles were ever built.

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