IDK if this has already been covered, but:
- The submersible had no sonar, correct? I read that the mother ship had to guide it to the the wreck via short “text” messages.
- So I assume the mother ship had its own sonar to do so, right?
- And if the US Navy heard the implosion
Then how in the hell did the mother ship not hear and understand immediately that the Titan imploded?

Exactly. The helmet and suit were not pressurized instantly at the full pressure of the environment. The suit acted like a roll of toothpaste, so as the suit was squeezed from the bottom up, and the helmet wouldn't (initially) succumb to the pressure, the suit squeezed the meat man into the helmet like the reservoir tip on a condom.

The Mythbusters example is not an apples to apples comparison. It's more like apples and oranges or maybe apples and strawberries.

I don't believe that the Navy's underwater listening devices are the same as SONAR. So even if the mothership had SONAR, that does not necessarily mean that they would have heard an implosion.

I suspect the current version is far removed from the version on wikipedia
https://en.wikipedia.org/wiki/SOSUS

what most folks think of is active SONAR. I suspect most active SONAR is automated, so the avg SONAR system echo-locates, but the system as purchased probably doesn't have a "I heard something under us implode" warning.
https://en.wikipedia.org/wiki/Sonar

I’m a little late to the scene, but is he suggesting that the Titan imploded at 3500 foot depth?

https://www.npr.org/2023/06/23/1183976726/titan-titanic-sub-implosion-navy

From the article:
“The listening system the Navy used to register the noise is believed to be the Sound Surveillance System or SOSUS, according to information shared with NPR by a senior Navy official. SOSUS, an underwater cable system that has been in place for decades, is capable of detecting underwater anomalies that might indicate the presence of foreign submarines.”

Personally, I’m thinking why would the mother ship be any better equipped than the sub-standard vessel.

Perhaps of interest:

https://www.cbsnews.com/news/titanic-submersible-interview-transcript-with-oceangate-ceo-stockton-rush/

"The other thing with carbon fiber is, you can't cut holes in it. It doesn't like that. And so these [cables] go into the titanium, and that's how we get our data in. So that's how you get things in and out of the sub, is through the little port."

"So the key on that one is, we have an acoustic monitoring system. Carbon fiber makes noise. There're millions of fibers there. There are 667 layers of very thin carbon fiber in this five-inch piece.

It makes noise, and it crackles. When the first time you pressurize it, if you think about it, of those million fibers, a couple of 'em are sorta weak. They shouldn't have made the team.

And when it gets pressurized, they snap, and they make a noise. The first time you get to, say, 1,000 meters, it will make a whole bunch of noise. And then you back off, and it won't make any noise until you exceed the last maximum.

And so when, the first time we took it to full pressure, it made a bunch of noise. The second time, it made very little noise.

We have eight acoustic sensors in there, and they're listening for this. So when we get to 1,000 meters, if all of a sudden we hear this thing crackling, it's, like, "Wait, did somebody run a forklift into it? You know, has it had cyclic fatigue? Is there something wrong?"

And you get a huge amount of warning. We've destroyed several structures [in testing], and you get a lotta warning. I mean, 1,500 meters of warning.

It'll start, you'll go, "Oh, this isn't happy." (LAUGH) And then you'll keep doin' it, and then it explodes or implodes. We do it at the University of Washington. It shakes the whole building when you destroy the thing.

So that's our backup for the hull. And we're the only people I know that use continuous monitoring of the hull."

"And as I said, the warning is about 1,500 meters. It's a huge amount of pressure from the point where we'd say, "Oh, the hull's not happy" to when it implodes. And so you got a lotta time to drop your weights, to go back to the surface, and then say, "Okay, let's find out what's wrong."

"Like, over here, we blew this one up. So this is all a one-third scale [model of the Titan]. We were able to blow this up intentionally, to hear what it's like with our acoustic monitoring system. What we wanted to verify was, we can detect the carbon fiber failing way before it happens, so that you can stop your descent and go to the surface.

And that's what we found out here. So we now know what this shape sounds like when it's uncomfortable and right before death.

It's the loudest thing I've ever heard in my life.

When you go beyond 6,000 PSI in the test chamber that we were using at the University of Washington, they have to empty the building. Only essential personnel can be there."

"Well, obviously, the hull is critical. And if the hull being carbon fiber—and being a unique material, and having the potential for things like water intrusion—but if that hull goes, that could kill people.
You wanna make sure it's infrequent and also detectable. And one of the ways to do detection is this acoustic monitoring system.

So we bench-checked it against the system that Boeing uses. We made our own system that was much smaller and more sensitive, actually.

And then we also have strain gauges. So we look at the hull every step of the way.

And so we get to 1,000 meters and the hull's acting differently, the strain gauge goes off, or the acoustic monitoring system is showing a lot of noise, you call off the dive. You come to the surface. You find out what's wrong.

And so that's what we tested with all of these components, taking it to destruction, and also testing at the deep-ocean test facility, the entire sub, and being able to see: What does it sound like on its first dive, and what's it sound like now? And we can keep comparing it and making sure it's still putting out that beautiful sound—of silence."

When the Navy lost the Thresher they theorized that the breach allowed it to fill so fast the hull didn't collapse.

acoustic emissions is a lot of things ... but a fail safe it is not. AE is a chaotic mess, and you dont actually know for certain what is happening.

also they are measuring the "warning buffer" in additional feet of pressure, but if its cracking, than its already failed and is weaker that it was before. ie, a better spec for that buffer would be a combination of time, and cycle count. it might not be 1500 feet of additional pressure (in this case the term would actually be head, but whatever), but if you left it at whatever pressure it was at when it cracked, over time, it would continue to crack likely. and if you removed that pressure, and added the same pressure again, you would see additional damage.

ie, the "warning buffer" he talks about here is a lot more complicated than he says it is. every single AE detection is a weakening of the structure.

EDIT: every interview with rush i read sounds like when elon billionaire-splains second year engineering school concepts like its ground breaking. rush sounds the exact same.

This is a ready good intro on Ocean Acoustics. It is fascinating to me since I lived the dream but will be a sleeping aid to others.

http://stream1.cmatc.cn/pub/comet/MarineMeteorologyOceans/IntroductiontoOceanAcoustics/comet/oceans/acoustics/print.htm

SOSUS has been around for a long time, even predating my time in the Navy.

https://www.csp.navy.mil/cus/About-IUSS/Origins-of-SOSUS/

So, all that said, SONAR is an active sensor, it puts out energy in the water and looks for a return. SONAR doesn't "listen". Passive arrays "listen" for noise in the water.

The difference is in anti-submarine warfare tactics: Active sonar is very critical in high ambient noise tactical scenarios, think inner zone ASW in the fleet. Ships make a lot of noise and active sonar is an imperative because the bad guys are in the hen house.

Once you "ping" they know more about you than you know about them.

Passive detonation is equally important but I'd key cramps writing why.

Lastly, the depth of the Titanic debris field is over two miles down. No tactical submarine in the world goes that deep. My curiosity is why the Titan needed guidance from above.

I agree. Sensor operators and their digital assistants look for anomalies in their "day in the life" analysis. It is fairly rare to have large noise swings in the water.

I have listened to snapping shrimp, whales yap, etc. Great stuff.

I will say, everything is recorded and analyzed. That is how we "hull type" other countries submarine, right down to the hull number.

we are talking about different things. im talking about the safety system in the sub to listen for the hull cracking ... not a hydrophone/passive sonar system.

wiki link: https://en.wikipedia.org/wiki/Acoustic_emission

Imagine if you jumped out of a helicopter two miles high. You have a parachute but its totally dark. Your target is something the size of the titanic. The wind is blowing 7 knots.

How far are you going to drift by the time you reach the ground? The viz is 30 feet and you have a flashlight.

If the mother ship had an active sonar they could ping the submersible and give corrections.

I remember a sonar friend calling a contact a G-U-ELEVEN

(that was a longgg time ago)

I think that was filmed on the USS Blueback. If I ever get off may rear and do a road trip to see friends in Washington I'll stop in Portland to visit it. The last time I saw it was in 91.

Sounds like yhe CEO was trying to be the SpaceX of the sea? Xsub?

Copy. My bad.

I still own 35% of a composites company, not thick composites but the discussion threads on this are very informative. There is a lot more to even simple composites than many can imagine.

When composites became more main stream for aircraft, the scrap rate for even the big manufacturers of thick composites, in my case when I was the IPT lead for the Bell Y/Z helicopters, was very high.

The amount of Destructive and Non-destructive analysis almost killed the program.

We do FAA composite repair work on commercial aircraft parts and the quals, tracking, inspections are brutal but they pay well.

Boeing had to make a couple wings for the X32 in order to get one that was acceptable.

That is what is most interesting to when combined with CP posts: how did they know, without multiple dives and post mission analysis then unmanned to failure with data capture, what was good versus bad noise emissions?

Happy to learn more.