OT: Ocean Gate Titan Confirmed Lost

CTMike

A couple hours ago, the US Coast Guard confirmed that Ocean Gate’s submersible Titan was lost with all hands:

https://thehill.com/blogs/blog-briefing-room/4063075-ocean-gate-statement-passengers-presumed-dead/

A little digging shows that the company was notified by many submersible experts that their design may be flawed:

https://www.nytimes.com/2023/06/20/us/oceangate-titanic-missing-submersible.html

EDIT: The NYT article is likely behind a paywall, here is a part that really hit home with me:

The separate warning that OceanGate received that same year came from 38 experts in the submersible craft industry; all of them were members of the Manned Underwater Vehicles committee of the Marine Technology Society, a 60-year-old industry group that promotes, studies and teaches the public about ocean technology. The experts wrote in their letter to Mr. Rush that they had “unanimous concern” about the way the Titan had been developed, and about the planned missions to the Titanic wreckage.

The letter said that OceanGate’s marketing of the Titan had been “at minimum, misleading” because it claimed that the submersible would meet or exceed the safety standards of a risk assessment company known as DNV, even though the company had no plans to have the craft formally certified by the agency.

“Their plan of not following classification guidelines was considered very risky,” Will Kohnen, the chairman of the committee, said in an interview on Tuesday.

The industry leaders said in their letter that OceanGate should, at minimum, test its prototypes under the watch of DNV or another leading certification company.

As a retired bubblehead, I would never consider submerging in something that hasn’t undergone an extensive review of the design, operation, maintenance, etc, let alone a design that depends on someone external to unbolt the hatch. 

Sad for the families involved. 

ColbyLang

Hopefully for those faithful souls it was a quick loss of life. Can’t imagine suffocating one by one if it had stayed in tact

dmchicago

I read something to the effect that death would have come in nanoseconds. 

Botch

Apparently there’s all kinds of data on the tensile strength of Carbon Fiber, but very little compression test data.  The actual sub was pressure tested to the required amount, once!  No idea what the fatigue strength might be.  
One SME said the pressure at the ocean floor was 3 tons/sq inch.    

JohnInCarolina

http://twitter.com/NoLieWithBTC/status/1671985127528726534?s=20

JohnInCarolina

Botch said:

Apparently there’s all kinds of data on the tensile strength of Carbon Fiber, but very little compression test data.  The actual sub was pressure tested to the required amount, once!  No idea what the fatigue strength might be.  
One SME said the pressure at the ocean floor was 3 tons/sq inch.    

Material failure here is governed by a strength surface, a three-dimensional surface in principal stress space.  The state of stress is actually a bit more complicated than uniaxial compression.  You might remember your stress states for pressurized cylinders (a decent enough approximation) from your undergraduate strength of materials course, Botch. 

There is also the very real possibility of more of a structural failure due to buckling of the walls, which is my best guess as to what likely happened.  

Regardless, it was surely brutal and fast, and perhaps there’s some saving that it happened very quickly and the passengers never had any idea.   

CTMike

Botch said:

Apparently there’s all kinds of data on the tensile strength of Carbon Fiber, but very little compression test data.  The actual sub was pressure tested to the required amount, once!  No idea what the fatigue strength might be.  
One SME said the pressure at the ocean floor was 3 tons/sq inch.    

General rule of thumb is 44 psi/100’ of depth. The Titanic is generally stated to be at ~ 12,500’, so 125x44 = 5,500 psi. Assuming the Titan is a straight cylinder 22’ long and 9.2’ in diameter (I know it isn’t a perfect cylinder but bear with me). 

Using the formula to calculate the area of the cylinder:

A = 2 x pi x r x h + 2 x pi x r^2 yields ~ 769 sq ft or 110,736 sq inches. Multiply that by 5,500 yields ~ 792,000 lbs of force on that hull. 

Granted this is a gross approximation as it doesn’t account for the surface area of the titanium end bells, or the tapered stern of the vehicle, but gives an idea of the forces involved.  

In my Naval Nuclear days we called these type of approximations ‘RadCon Math.’ It gets you close enough to the answer to appreciate the forces involved. 

@lousubcap - Does this remind you of EOOW/EWS training?

CTMike

Turns out the Navy identified an implosion in the area on Sunday via SOSUS, and this information was relayed to the USCG Incident Commander:
https://www.independent.co.uk/news/world/americas/titan-submarine-implosion-navy-debris-microphones-b2362685.html

Botch

JohnInCarolina said:
The state of stress is actually a bit more complicated than uniaxial compression.   

A lot more complicated, as the end caps were titanium, not CF, and there was a Plexiglass window too.  

CTMike

Botch said:

JohnInCarolina said:
The state of stress is actually a bit more complicated than uniaxial compression.   

A lot more complicated, as the end caps were titanium, not CF, and there was a Plexiglass window too.  

A plexiglass window that according to a former Ocean Gate employee/whistleblower was only rated for 1,300m, not the 4,000m it was exposed to:

Lochridge said he first raised his safety and quality control concerns verbally to executive management, which ignored them. He then sought to address the problems and offer solutions in a report.

The day after it was submitted, the lawsuit says, various engineering and HR executives invited him to a meeting at which he learned that the viewport of the submersible was only built to a certified pressure of 1,300 meters, even though the Titanic shipwreck lies nearly 4,000 meters below sea level.

Ozzie_Isaac

Having been involved in building pressurized cylinders with stainless inside and carbon fiber wrap outside, and pressurized in excess of 6k psi, when I saw the video of the cylinder being wrapped it literally made my stomach churn.  Then add in lack of testing and this submersible was always going to end in tragedy.  Very sad indeed.

CTMike

Ozzie_Isaac said:

Having been involved in building pressurized cylinders with stainless inside and carbon fiber wrap outside, and pressurized in excess of 6k psi, when I saw the video of the cylinder being wrapped it literally made my stomach churn.  Then add in lack of testing and this submersible was always going to end in tragedy.  Very sad indeed.

Agreed, it seems they just got incredibly lucky on the previous dives.  

jdMyers

Heck even Columbian drug traffickers mastered narci subs better.

JohnInCarolina

CTMike said:

Ozzie_Isaac said:

Having been involved in building pressurized cylinders with stainless inside and carbon fiber wrap outside, and pressurized in excess of 6k psi, when I saw the video of the cylinder being wrapped it literally made my stomach churn.  Then add in lack of testing and this submersible was always going to end in tragedy.  Very sad indeed.

Agreed, it seems they just got incredibly lucky on the previous dives.  

One feature of fatigue is that systems withstand loads … until they don’t. 

stv8r

I read a story that said the viewing window was not certified to withstand the pressure at that depth.  It said the company didn't want to spend the money to get one that was certified.  Who knows with so much disinformation circulating. 

CTMike

stv8r said:

I read a story that said the viewing window was not certified to withstand the pressure at that depth.  It said the company didn't want to spend the money to get one that was certified.  Who knows with so much disinformation circulating. 

See my post above about former employee/whistleblower and the viewing port. 

Ozzie_Isaac

I found this particular analysis pretty decent.  Mirrored a lot of my thoughts.

https://youtu.be/4dka29FSZac

Gulfcoastguy

yes and the guy who talked his 19 year old son into going with him for Father’s Day. That might have ended a family.

HeavyG

https://twitter.com/mirandadevine/status/1672015817653796864

Those idiots will politicize anything. Farging iceholes.

Ozzie_Isaac

HeavyG said:

https://twitter.com/mirandadevine/status/1672015817653796864

Those idiots will politicize anything. Farging iceholes.

Seriously, who gives a flying gaddamn **** about Hunter Biden?  So Joe had a **** up kid with issues. Turns out, that isn't very uncommon.  Hunter ain't president.  Who cares.  I miss the days when we focused on policy and the actual president.

ksmyrl

Since when is Twitter a reliable source of...anything?

HeavyG

ksmyrl said:

Since when is Twitter a reliable source of...anything?

Her opinion, already shared by many of those in that clown car, has nothing to do with the reliability of Twitter or the WSJ.

lkapigian

Travesty , but I’m glad the world set their differences aside and unite in the hope of bringing them home 

HeavyG

For anyone interested in taking a deeper dive (so to speak) into the carbon fiber hull here's an interestinig thread:

https://twitter.com/d_feldman/status/1672072299451752451

CTMike

HeavyG said:

For anyone interested in taking a deeper dive (so to speak) into the carbon fiber hull here's an interestinig thread:

https://twitter.com/d_feldman/status/1672072299451752451

Whoever Daniel Feldman is should probably learn the difference between an explosion and an implosion before trying to come across as some type of SME.

alaskanassasin

Strange one, go with dad and die, or stay home dad dies and you were right it was too dangerous. tough position to be in.

Langner91

Ozzie_Isaac said:

HeavyG said:

https://twitter.com/mirandadevine/status/1672015817653796864

Those idiots will politicize anything. Farging iceholes.

Seriously, who gives a flying gaddamn **** about Hunter Biden?  So Joe had a **** up kid with issues. Turns out, that isn't very uncommon.  Hunter ain't president.  Who cares.  I miss the days when we focused on policy and the actual president.

So true!  Who cares about what the President's son does?  It should never spark a Congressional or DOJ investigation!  Witch HUNT.  Leave the kids alone!

LOL.

alaskanassasin

Also sitting here thinking of a way to spend 200k on a experience vacation with swmbo. It would be epic. Blue origin? does not sound like fun. hmm

Ozzie_Isaac

alaskanassasin said:

Also sitting here thinking of a way to spend 200k on a experience vacation with swmbo. It would be epic. Blue origin? does not sound like fun. hmm

$200k total or per person?

alaskanassasin

Ozzie_Isaac said:

alaskanassasin said:

Also sitting here thinking of a way to spend 200k on a experience vacation with swmbo. It would be epic. Blue origin? does not sound like fun. hmm

$200k total or per person?

 Total bro. I am thinking a regular vacation that lasts a year lol.

Ozzie_Isaac

Langner91 said:

Ozzie_Isaac said:

HeavyG said:

https://twitter.com/mirandadevine/status/1672015817653796864

Those idiots will politicize anything. Farging iceholes.

Seriously, who gives a flying gaddamn **** about Hunter Biden?  So Joe had a **** up kid with issues. Turns out, that isn't very uncommon.  Hunter ain't president.  Who cares.  I miss the days when we focused on policy and the actual president.

So true!  Who cares about what the President's son does?  It should never spark a Congressional or DOJ investigation!  Witch HUNT.  Leave the kids alone!

LOL.

I think a key point is Don Jr. worked in the administration.  If he did, then that should be scrutinized.