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Why isn't Titan classed? (2019)

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Re: Why isn't Titan classed? (2019)

#171

Post by jnwatson »

_yb2s wrote: post #119
AdamJacobMuller wrote: post #58

Earlier quoted context omitted.

Truly bizarre. Failures like this happen in milliseconds, it doesn't matter how realtime your realtime monitoring is. I'm not arguing in favor of the classification system, but, I think if you went to them and framed things as simply as they are here "you require validation every 3 years, we're doing it on every single dive" they would say "that's more than once per 3 years, APPROVED!" so the situation is clearly far…

Yes, I don't understand this acoustic monitoring concept... I'm curious what the logic behind it was. It just doesn't seem like there would be enough time to take action once the monitor starts to detect failure.

It depends on the material. It might work for certain tours of steel, since the failure state is gradual.

Carbon fiber, however, is not known to gradually fail.

Re: Why isn't Titan classed? (2019)

#172

Post by sacnoradhq »

dghlsakjg wrote: post #43

> They [inspections] do not ensure that operators adhere to proper operating procedures and decision-making processes – two areas that are much more important for mitigating risks at sea. As a former tall ship captain: No Shit. Ships stopped sinking when we started requiring inspections and design rules around stability and watertight compartments. We largely eliminated a common failure mode, designer error, through…

Arrogance and overconfidence lead inexorably to hubris and they won a Darwin Award for thinking they "knew better". It's obvious they skimped on testing and were too cavalier with unproven "innovation".

Re: Why isn't Titan classed? (2019)

#173

Post by [deleted] »

AdamJacobMuller wrote: post #53
cbzoiav wrote: post #26

Earlier quoted context omitted.

The craft survived several launches - that proved it can do it. Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.

As far as I'm aware, and please correct me if I'm wrong, they had never dove to this depth before. So, sure, it was launched before and recovered, but it never experienced the same conditions which caused the failure.

[deleted]

Re: Why isn't Titan classed? (2019)

#174

Post by zippothrowaway »

noduerme wrote: post #139
aaronscott wrote: post #100

> Another simple risk mitigation step we take, that we believe to be unique to OceanGate is that we draw a small vacuum on the inside of the sub at the start of each dive. This step verifies the integrity of the low-pressure O-ring seal and eliminates the risk of leaks I wonder what that low-pressure o-ring is sealing. I assume the vacuum would only simulate a one atmosphere differential, so that o-ring must not be s…

One thing I'm curious about, as someone who knows nothing about the engineering of these things... why wouldn't anyone building something like this choose to over-pressure the sub once people were inside it and it began descending? Wouldn't 2 atmospheres inside represent a 50% reduction in the pressure differential on the hull at depth?

Outside pressure is 300 x atmosphere so a difference of 299 atmospheres. Increasing to 2 internally makes a difference of...298 atmospheres.

Re: Why isn't Titan classed? (2019)

#175

Post by sacnoradhq »

cjensen wrote: post #71
dghlsakjg wrote: post #43

> They [inspections] do not ensure that operators adhere to proper operating procedures and decision-making processes – two areas that are much more important for mitigating risks at sea. As a former tall ship captain: No Shit. Ships stopped sinking when we started requiring inspections and design rules around stability and watertight compartments. We largely eliminated a common failure mode, designer error, through…

Yep. This is like saying "who needs building codes because it's more important the owner maintains the roof and paint?" To have something properly function you need both a solid build and maintenance. Doing one well doesn't absolve you of doing the other.

Emperor's new clothes syndrome of the naïve and/or arrogant.

Re: Why isn't Titan classed? (2019)

#176

Post by mustacheemperor »

_yb2s wrote: post #119
AdamJacobMuller wrote: post #58

Earlier quoted context omitted.

Truly bizarre. Failures like this happen in milliseconds, it doesn't matter how realtime your realtime monitoring is. I'm not arguing in favor of the classification system, but, I think if you went to them and framed things as simply as they are here "you require validation every 3 years, we're doing it on every single dive" they would say "that's more than once per 3 years, APPROVED!" so the situation is clearly far…

Yes, I don't understand this acoustic monitoring concept... I'm curious what the logic behind it was. It just doesn't seem like there would be enough time to take action once the monitor starts to detect failure.

It seems they felt this was one of the novel innovations that enabled this design - that the monitoring system was so good, they'd never be at risk in the pressure hull at depth.

James Cameron said it looks like they had dropped their emergency ascent ballast before the implosion, so they may have gotten enough warning to take action. But I would guess that system was never tested to failure in real life.

It will be interesting to see which of the novel innovations supposedly enabling this unconventional design failed, if it can be determined. Rush also lampshaded the fact that his company had "successfully" bonded the titanium endcaps to carbon fiber despite that being contradictory to conventional materials science wisdom, reading the patent for the monitoring system it looks like it may have been intended to provide warning about those bonds failing too.

Re: Why isn't Titan classed? (2019)

#177

Post by ineedasername »

cbzoiav wrote: post #26
hn_throwaway_99 wrote: post #22

> OceanGate’s submersibles are the only known vessels to use real-time (RTM) hull health monitoring. With this RTM system, we can determine if the hull is compromised well before situations become life-threatening, and safely return to the surface. This innovative safety system is not currently covered by any classing agency. > No other submersible currently utilizes real-time monitoring to monitor hull health during…

The craft survived several launches - that proved it can do it. Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.

>Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.

Seems like we already found out the answer is “no”. The overall ship design failed.

Re: Why isn't Titan classed? (2019)

#178

Post by proggy »

stickfigure wrote: post #73
cbzoiav wrote: post #16

> The vast majority of marine (and aviation) accidents are a result of operator error, not mechanical failure. Could that be because the vast majority of mechanical designs go through processes designed to validate them and catch flaws? They also use SpaceX as an example. SpaceX ran a large number of unmanned launches to prove out the design before putting people on board. Several of those ended in loss of the vehicl…

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

One of the shuttle missions that resulted in loss of crew was caused by operating the vehicle outside of the rated temperature envelope (for the SSB O-rings). If that requirement was honored, the failure rate could have been halved.

The other loss of crew was caused by a genuine oversight in the design of the system, in that the orbiter was always susceptible to strikes from insulating foam falling from the external tank.

Unlike Titan, neither one of these failures were due to the inevitable cyclic wear of the primary pressure vessel. They were both devils hiding in the details, neither one the result of reckless hubris.

OceanGate full on admitted that its carbon fiber hull, a major red flag component at the center of its design, was highly experimental and did not know exactly when it would fail. They foolishly thought that strain gauges would detect issues well in advance of failure, while completely ignoring how immediately and catastrophically composite structures are known to fail. They recklessly sold tickets to fund their experimental craft, inviting people aboard who were definitely not made fully aware of just how flawed the design was up front. These were not all members of the Explorers Club — a former head writer for the Simpsons went on a dive, for goodness’ sake.

So to return back to your point, I’d rather take a shuttle after a few dozen flights than get inside a Titan II after a few dozen dives.

Re: Why isn't Titan classed? (2019)

#179

Post by pengaru »

cactusplant7374 wrote: post #153
pengaru wrote: post #90

Earlier quoted context omitted.

> Although, couldn't they just leave it at the bottom for a month and see if it implodes? No, cyclic stresses are a different animal altogether. But considering it's just a matter of attaching ballast to sink it, dropping ballast to raise it, there's nothing preventing cyclic testing vs. static @ max depth over the same duration. It seems obvious to me that you'd want to burn through a few test hulls characterizing t…

Each time they go down they have to jettison some waste to return to the surface?

I'm no sub nerd but it seems obvious that unless you can otherwise alter your buoyancy somehow, your only option is to drop weights.

I think submarines use ballast tanks they flood with sea water and empty with pumps to vary their buoyancy. Titan had none of that complexity AIUI, and multiple articles I read mentioned dropping "ascent weights".

Re: Why isn't Titan classed? (2019)

#180

Post by sebzim4500 »

spencerflem wrote: post #109
stickfigure wrote: post #73

Earlier quoted context omitted.

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

Its a big hackernews meme that NASA spends way too much on safety/beurocracy instead of innovation. Plenty of other submarines companies do the same (and get classed). I don't think this is a very insightful comparison.

I don't think anyone objects to NASA spending money on safety for crew. The fact that an uncrewed SLS launch costs $4B is insane by any standard.
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