Titan sub noise heard on board support ship. 2

[LittleInch]

Just watched a new documentary by the BBC and others like Discovery so if you're interested look out for it. Implosion: The titanic sub disaster.

Key new part for me is that they released video of the moment a loud "crump" was actually heard on board the support vessel apparently through the hull with Rushs wife Wendy doing the monitoring of the sub and her saying "what was that?". They then got a message from the sub which must have been somehow delayed saying dropped two weights which confused them. It is pretty chilling to listen to alright. That and the fact that they were thought not to be at the ocean floor implies they were getting some warnings.

This is a clip but there are others.

Not much we didn't already know, but they have noted dive 81 (out of 88) where there was a very large bang heard which they reckon was the point at which the hull was on its last legs after a major internal failure.

The Discovery documentary maker back in 2022 was very unimpressed with the whole thing and persuaded the company to can their documentary as he was convinced it would end in failure and didn't want to be seen to promote the operation.

Looks like it's on Discovery pretty soon. If you're interested, it's pretty good and not that big into the human interest side, but does have input from the wife of the man and his son that died which is quite moving.

How to watch 'Implosion: The Titanic Sub Disaster' - Stream the thought-provoking documentary online

Scientists explore how the Titan submersible implosion was more than just a tragic accident

www.tomsguide.com

 

[TugboatEng]

It wasn't a fatigue failure. We saw the video or the dome being bonded to the CF hull. The joint was not properly prepared with regards to removing the passive layer prior to bonding. In the picture, the rear done separated cleanly and the rest of the hull is shoved into the forward dome indicating the failure started at the rear. We saw the rear done. recovered. The adhesive is no longer adhered to the dome. Finally, we saw the inner flange of the rear done sheared off indicating movement of the hill relative to the dome after the adhesive failed.

The improper prep before bonding started a timer to failure as soon as the sub was exposed to water, stress not required.

 

[IRstuff]

The review of the Netflix documentary misses one key segment, where Rush does a solo dive, and you can hear a continual stream of pops from the carbon fibers breaking.

That should have terrified any rational person.

Another thing in the documentary that was new to me was that the Titan was supposedly stored in Canada over the winter, which makes me wonder if there was freeze/thaw involved in further weakening the hull, since that immediately previous dive resulted in a slew of carbon fiber breakage sounds, possibly leading to water entrapment in the hull

 

[Tomfh]

It was clearly a fatigue failure. With each dive further damage occured. As Brian Malone mentioned you could hear this cumulative damage occuring all the way down. Crack, bang.

The severe cracks in the old hull told the story of what was happening with all the creaks and groans. It was the progression of fatigue damage. Hence it failing at 3300m on the final dive.

 

[Tomfh]

I wonder if even if OceanGate had put the design through a classing certification if that would have caught the potential failure mode?

Yes, and it would have caught a whole lot more things too, things that in Rush's view were pedantic "safety" stuff. That's why he didn't want it classed. Classing was far too conservative from his point of view.

 

[TugboatEng]

The only evidence of fatigue were the popping sounds. I wouldn't call that clear evidence of a fatigue failure.

 

[IRstuff]

It's just a different type of fatigue, not unlike work hardening.

 

[TugboatEng]

I can't view the articles but Grok apparently can. This is what I've been trying to describe:


"Hydration of Titanium Oxide in Adhesive Interfaces (ScienceDirect, 2017)
This study investigates adhesive bonding to titanium oxide (TiO₂) surfaces, commonly found on titanium substrates in aerospace and biomedical applications. TiO₂ surfaces are highly hydrophilic due to surface hydroxyl (Ti-OH) groups, which form a hydration layer (approximately 10–15 Å thick) in humid environments. This layer hinders adhesive contact, particularly for non-polar adhesives like epoxies. Silane coupling agents (e.g., (3-aminopropyl)-trimethoxysilane) enhance adhesion by forming Si-O-Ti bonds, displacing interfacial water. However, prolonged exposure to moisture leads to titanium hydrate formation (e.g., Ti(OH)₄), which weakens the oxide layer and reduces bond strength. The study suggests that controlling humidity during bonding and using siloxane-modified adhesives can mitigate hydration-induced degradation."

None of these measures were taken during the bonding of the domes and the failure appears to have initiated at the rear of the sub, possibly at the bond between the dome and the hull. If the failure was a result of fatigue of the CF, I would expect the failure to occur at the center of the hull.

 

[DennisR4]

This Thread is going seriously off topic.....

Has anyone else managed to see the documentary?

Saw the one on HBO Max, and the Netflix one. They were both pretty good, although they were vastly different. The Netflix one was spine tingling, showing footage from inside the sub on test dives, and you can audibly hear the carbon fiber cracking and popping. SR was an idiot, but he had balls of steel.

 

[thebard3]

Saw the one on HBO Max, and the Netflix one. They were both pretty good, although they were vastly different. The Netflix one was spine tingling, showing footage from inside the sub on test dives, and you can audibly hear the carbon fiber cracking and popping. SR was an idiot, but he had balls of steel.

One might confuse hubris and ignorance for courage, though.

 

[IRstuff]

One might confuse hubris and ignorance for courage, though.

Definitely hubris, but not ignorance, per se, in the "stupid" sense ; he "ignored" experts, because of his hubris, and possibly, he knew at some level that the experts were usually correct, and that his suppositions were seriously flawed and that classing the vehicle would prove that his dream had serious flaws. In the Netflix documentary, they showed that in every test, the hull could not handle the pressure, and he was specifically warned, in a written report, that the hull was more than likely to fail at pressure, which he ignored, so he "knew".

 

[Tomfh]

SR was an idiot, but he had balls of steel.

A fair assessment.

For all the valid criticism Stockton Rush cops, playing Russian roulette with peoples lives, I can’t help but feel some level of admiration for him. Utterly reckless, but bold in a way most people just aren’t.

 

[Brian Malone]

 Tomfh - I get what you are saying. If the Titan had survived long enough for Stockton and the OceanGate team to figure out the design and fabrication method for a reliable and safe hull, they would have been celebrated for pushing the limits of technology, and pursuing a goal with a 'damn the bullets' attitude. I don't think Stockton thought he was risking his life or that of his passengers (mission specialists . . .). How he was able to reconcile the failures of the 1/3 scale test hull failures with the apparent survivability of the full size hull, to risk fully manned dives is going to remain unanswered. He did not appear to have a death wish or suicidal tendency.

 

[waross]

A "Do or Die" attitude taken to the ultimate conclusion.

 

[Tomfh]

How he was able to reconcile the failures of the 1/3 scale test hull failures with the apparent survivability of the full size hull, to risk fully manned dives is going to remain unanswered.

I think the documentary glossed over the design and development process a little. It made it seem like, after a few early test failures, Stockton Rush jumped straight into a full-size sub. But if you look closely, those early failures appeared to involve failed carbon fibre end caps. Presumably that’s why the final sub used titanium ends.

Rush likely thought the problems were behind him: the cylindrical carbon fibre hull concept had (presumably) passed pressure tests, and the titanium end caps were solid. So in his mind, the design was validated. But he hasn’t counted on the slow progression of microcracks thru the cylindrical hull.

 

[TugboatEng]

Or the difficulties associated with bonding to titanium in wet environments.

 

[CWB1]

The Netflix documentary was interesting but I believe distorted by former employees blaming the dead boss to CYA. Ultimately yes, SR was responsible for the culture and safety but the employees turned a blind eye, enabling it as long as possible. The original engineering team was largely recent grads led by a few minimally experienced engineers, and purportedly not paid well. Personally, I've passed on top-paying opportunities on better teams to avoid risking my reputation in safer industries, and find the thought of such inexperience designing a passenger sub to be blatantly reckless - no way I'd ever consider hiring anybody associated with this company.

I was also a bit disappointed with the documentary as I was hoping there would be good coverage of the final dive, video aboard the surface ship when the sub went missing, and search/recovery but they pretty quickly glossed over all that.

 

[Brian Malone]

Tomfh -
I understand the confidence in your statement in Post #64.

I have found some info on "Classing Testing" which has been constantly mentioned but never described in any detail. If OceanGate had followed even a partial set of the test prescribed by the ABS - just one of many certifying bodies, the tragic outcome probably could have been avoided.
One recognized body for classing a submersible is the American Bureau of Shipping (ABS). Their classing standard explicitly excludes the use of carbon-fiber construction for human-occupied pressure vessels but a designer can apply for creating an ASME PVHO Case for the use of non-standard materials and the testimg and results would be submitted for review and approval. The Case Testing would be based on that used for metallic Pressure Vessels, Human Occupied (PVHO), and calls out for these tests:
‐------------------
Non-mandatory Appendix D of ASME PVHO-1 ( for non-standard designs and materials)
- Requires detailed information on the proposed materials, along with a detailed design analysis considering all applicable loads and environmental conditions.

Prototype hull proof testing:
3 full-size pressure hulls to be pressure tested to 6 times the Maximum Allowable Working Pressure (MAWP) without failure.

Creep testing:
Model or full-size hull to be subjected to 10,000 hours ( 1 year and 1-1/2 months) of sustained pressurization without failure. Options including testing 1 hull to 3 times MAWP or 5 hulls to 2 times MAWP.

Cyclical testing:
Full size pressure hull to be cyclically tested to multiple cycles to MAWP. The number of approved operational cycles will limited to half the number of tested cycles minus 1,000.

Production hull qualification testing:
Pressure hull tested to 1.5 times MAWP for 1 hour.

Third-party witness to all testing is required. All testing is to be witnessed by an independent recognized agency and signed off.

Externally pressured hulls shall be proof-tested hydrostatically to 1.25 times the design depth for 2 hours.

For external proof-testing traxial strain gauges shall be fitted in-way of hard spots and discontinuities.
- Location of the strain gauges and the maximum values of stress by the design at each location shall be submitted for approval prior to testing.
- Strain gauge measurements to be recorded after shakedown effects have ceased.
- The designer is to submit a report comparing the calculated stresses versus the measured stresses, in order to validate the design of the pressure hull.

Following the hydrostatic pressure test:
- The pressure hull welds are to be non-destructively inspected.
- Out-of-roundness measurements are to be taken and reviewed for compliance with the acceptance criteria. These measurements are to be retained as reference values for the life of the hull/submersible.
‐-------------------
This excerpt I took from some of the docs on file from the Coast Guard board of inquiry. I watched quite a few hours of the proceedings but I don't remember hearing any of the ABS classing test requirements being compared against the testing OceanGate had on file or presented for review.

 

[Brian Malone]

The cyclical testing regimen of a Classing Cert would have caught the failure whether it was the CF hull or the bonds at the Ti domes. A minimum of 2002 pressure cycles would have been required to state Titan was qualified for a single dive while carrying humans.