[Thad E Ginathom]

Originally Posted by Brumby

OceanGate is a registered company and their ocean going crafts must have been registered somewhere.

Probably true. The mother ship is, most likely, registered and subject to relevant maritime law. Vessel Polar Prince (gosh, it's almost as old as I am!). It was chartered by Oceangate.

However, it has been said (paraphrased from my memory of things read here and elsewhere,and I admit that may be deficient) that...

1. The Titan submersible had not been independently tested or verified by any external organisation.

2. The Titan submersible was not an ocean-going craft, it never as such departed or arrived any port, and therefore lived in an area of loopholes where no registration was required or done.

They must be having license to operate international VHF radios registered with service provider so, legal action proceedings will be there.

I don't think VHF radio has anything to do with it. Anyone can buy/fit a marine VHF radio, there is nothing international about it as it is a short-range system, there is no service provider. Even I have a marine VHF radio operator's licence.

They must have made the clients to sign an indemnity to cover themselves

This has been covered in the news. Clients signed an extensive waver, disclaimer, and acknowledgement of risk. Apparently, the word death featured in it several times.

Questions for our sea-going pros...

I'm imagining that the ship would be chartered with crew etc for short periods. It doesn't seem possible that such a small company would maintain the expense and problems of a ship on a full-time basis. Is this how it works?

It seems the ship flew under the flag of Canada. Am I right in thinking that this is not one of the regulations-light "flags of convenience?" I read that Canadian authorities are investigating.

Edit...

My question party answered...

The ship, a former Canadian Coast Guard vessel, is owned by the Miawpukek First Nation in southern Newfoundland. The chief and company issued a statement on Thursday.
“We want to commend our crews on the Polar Prince and Horizon Arctic who have worked tirelessly over the last number of days on the search and rescue effort. The work the crews and contractors have carried out under these difficult circumstances is a testament to their professionalism and dedication to their work,” the statement said.

Source.

[dragracer567]

Originally Posted by Jeroen

How do they design, manufacturer and test carbon fibre parts in the aviation industry if they could shatter just like that?

Jeroen



Jeroen

Doesn't the 787 and A350 have many carbon fibre parts? Also, the HAL Tejas is known to embrace carbon fibre for its wings!

[Ton Ami]

First things first. The customers paying 250k $ were no ordinary folks, they were super rich who knew risk assessment very well (presumably).

When a Naval submarine is restricted to a depth of few hundred metres (officially) then what were these guys smoking when they decided to trust a small company to take them to diving depth of thousands of meters.

Every dive impacts the structure due to pressure exerted on external hull. Each passing voyage is therefore more riskier than the previous one. The titan must have been identified as an onboard equipment rather than a submarine so less scrutiny for tests and certifications (I think its a grey area..).

If you ask me, whether I will take an adventure trip in such vessel even if the company pays me $250K, I will say a resounding NEVER. I have claustrophobia and am sceptical about shady companies using unconvincing technologies for out of the world experience. RIP five souls.

[Jeroen]

Originally Posted by dragracer567

Doesn't the 787 and A350 have many carbon fibre parts? Also, the HAL Tejas is known to embrace carbon fibre for its wings!

Yes, that is the point. Aviation industry and other make extensive use of carbon fibre. A 787 has about 20% of its parts made out of Carbon fibre or more precisely various composite materials.



Jeroen

[Formula1]

Aeronautical and Naval applications are very different though. Here we are talking compression. Aero wings don't really undergo compression. Not to mention the magnitude of pressure difference.

It's (kinda) clear to me that the only reason was "carbon fibre strong, carbon fibre light, carbon fibre cheap". It was a terrible choice.

[srvm]

Originally Posted by dragracer567

Doesn't the 787 and A350 have many carbon fibre parts? Also, the HAL Tejas is known to embrace carbon fibre for its wings!

Originally Posted by Jeroen

Yes, that is the point. Aviation industry and other make extensive use of carbon fibre. A 787 has about 20% of its parts made out of Carbon fibre or more precisely various composite materials.
Jeroen

Actually, the airframe of Boeing-787 and Airbus-350 have about 50% composites by weight. Not all of the composite in them is Carbon fiber composite but MOST of it is.
You can check the fact here: https://www.sciencedirect.com/scienc...28133088000065.

{ The author of above book (Prof Victor Giurgiutiu, University of South Carolina, Columbia, USA), trust me, is one of the best and reputed in this field }

Our LCA-Tejas has about 45% airframe weight in composites - Wing, Fin, Rudder, Fuselage parts, Landing gear doors etc.

Originally Posted by Formula1

Aeronautical and Naval applications are very different though. Here we are talking compression. Aero wings don't really undergo compression. Not to mention the magnitude of pressure difference.

It's (kinda) clear to me that the only reason was "carbon fibre strong, carbon fibre light, carbon fibre cheap". It was a terrible choice.

The part highlighted above couldn't be more erroneous. Pardon me sir, if you aren't 100% sure about a topic, please don't post such erroneous stuff misdirecting others in public forum.

It is quite possible that designers of Titan did choose composites for hull application for all the wrong reasons. But one cannot conclude that without having facts at hand.

The magnitude of pressure at that depths are known. It is possible to make hulls with composite to take such compressive loads (For e.g. simply by making the hull thicker to cater for higher pressure loads). The key is if they took all such details, parameters into account during design, fabrication and assembly. Other parameters for instance are: Corrosion due to salt-water exposure, Joints between composite-composite, composite-metal etc.

[venkat_partha]

Originally Posted by srvm

Kindly allow me to add a few points even though it is not specific to Titan's failure.

With so many potential points of failure, did they cut corners in the safety department? Was the sub (ab)used to its limits without proper safety oversight?

[Formula1]

Originally Posted by srvm

The part highlighted above couldn't be more erroneous. Pardon me sir, if you aren't 100% sure about a topic, please don't post such erroneous stuff misdirecting others in public forum.

I apologise for my simplistic takes on the matter. Nobody should take my words seriously.

Aero wings absolutely undergo "compressive tension", as do most applications. Hence the "not really", to imply that I'm being simplistic.

By "compression", I mean isotropic compressive stress, which some simply call hydrostatic.

Essentially, I was just saying that wings don't get crushed from all directions. From what I know (which isn't a lot), composites aren't great for these applications.

As I said in a previous post, you can make anything work with the right parameters. But when lives are on the line, perhaps you shouldn't.

[ecenandu]

https://www.youtube.com/watch?v=YVvKk-rGJME

This came into my mind when I heard about the Titan submarine implosion, the repeated pressure cycle must have weakened the structure of the carbon hull.

In the case of Comet, a square window design was the cause for failure.

[Jeroen]

Originally Posted by ecenandu

This came into my mind when I heard about the Titan submarine implosion, the repeated pressure cycle must have weakened the structure of the carbon hull.

In the case of Comet, a square window design was the cause for failure.

The square windows on the Comet had problems with the repeated pressurisation cycles of the cabin. The comet was the first commercial jetliner that had a pressurised cabin. Due to these cycles it developed fatigue stress cracks.

I mentioned the comparison between the Comet disaster and this accident in one of my earlier posts. Whether such effect was the cause of this tragedy remains to be seen.

I saw an image of some of the debris they recovered. Including the titanium bulkhead. What was remarkable the sling on which it was hoisted was slung through the porthole. What happened there?



I took this image from one of the many articles floating around the Internet.
No idea, but it is at least remarkable.

These viewing portholes have a conical shape, so the glass (or whatever it’s called/made from) gets pressed into it by the water pressure. Maybe the hull imploded causing it to be popped out? Of course, once the hull is ruptured ultimately the pressure in and outside are identical. But I could imagine the sheer impact of the seawater rushing in at these depth could have sufficient kinetic energie to destroy the porthole from the inside out.

Jeroen

[anoopGTkrish]

Carbon composites have always been an area of interest for me. During my engineering days, we worked on a project with ISRO for their Chandrayaan mission.

Objective was to design a lightweight, mesh structure flange that connects the solar panels of the orbiter to the main body and orient it to face the sun. This was back in 2009 and we were genuinely intimidated working with the material. We did extensive CAD designs and load simulations in Ansys. The way composite materials distributed the load was based on how the composite sheets are layered, the type of weave and the design of the frame itself. Also the manufacturing itself was really complex as these sheets had to be layered over a thin layer of epoxy applied uniformly and then cured slowly in an autoclave oven. There were trained experts for this.

Now reason I mentioned this is that, space is an equally unforgiving environment as the deep sea. Temperature variations over the course of a 24 hour period are extreme and materials that fatigue from temperature variations won't fare in that environment. Still space research organizations heavily utilize carbon composites for the light weight, ability to mould complex shapes, rigidity and strength. Though brittle, they can also offer a fair amount of flex in structures if designed with the intent. So its not exactly a bad choice of material for the environment. A better design or more rigorous testing ahead of every journey could've avoided the disaster.

[NomadSK]

Finally they have suspended all exploration and commercial activities.

https://edition.cnn.com/2023/07/06/u...an-submersible

[AutoNoob]

Originally Posted by anoopGTkrish

Now reason I mentioned this is that, space is an equally unforgiving environment as the deep sea... Though brittle, they can also offer a fair amount of flex in structures if designed with the intent. So its not exactly a bad choice of material for the environment. A better design or more rigorous testing ahead of every journey could've avoided the disaster.

Thanks for sharing. I don't have any working experience with carbon fiber composites, so guide me if I am wrong.

From what I have read, these composites are excellent under tension, but do not perform well under compressive forces. I think that's the key difference between space and deep sea applications. I think in space compressive loads are minimal, whereas in deep sea there's only compressive load, that too of very high magnitude.

Titan made successful trips to the deep sea, so the design was not faulty from the inception, but I think they failed to sufficiently account for load cycling.

[Thad E Ginathom]

Originally Posted by AutoNoob

... ... ... Titan made successful trips to the deep sea, so the design was not faulty from the inception, but I think they failed to sufficiently account for load cycling.

It's going to fail. We don't know when, but it's ok so far. Isn't that faulty design from the inception?

[Formula1]

Nothing that we haven't discussed, but:

https://youtu.be/6LcGrLnzYuU