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Tourist submersible visting the Titanic is missing 101

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Swccomposites said:
At person/entity is probably lawyering up and keeping as quiet as possible.
Click to expand...

Fun times. It’ll be interesting to see who the blame finally lands on.
 
MikeC88 said:
What is the impact resistance of CF like in this form?

My only experience is with thin walls (bike frames & paddles) but I noted in a video on YouTube by dallymd that a weighted mooring line has been thrown out to the sub 15:55 timestamp) and impacted the vessel.

In this case the weight hit the control section at the rear,not the CF passenger section, but it makes me wonder if this was standard operating procedure and whether the sub may have picked up damage.
Click to expand...

Going by the photographs, the CF hull was covered by a white fairing/shell, presumably for a mix of protection and appearance. It certainly looks to me like it would protect the CF hull from minor impacts and abrasion. One of the infographics above describes it as a fibreglass shell (I'd guess possibly epoxy-kevlar, if they wanted to be fancy about it and minimise weight), which makes reasonable sense. There are clear lines of screw fasteners (or similar) on it, so it would not be bonded directly to the CF hull, but mounted over it on some sort of spacer arrangement.
 
Fun times. It’ll be interesting to see who the blame finally lands on.
Click to expand...
Don't they always blame the dead guy?

--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
The press release from 2021 in Cool Control's link lists PH Nargeolet on the ground-breaking dive to the Titanic. So Mr. Nargeolet, who was a world-renowned deep-sea explorer and Titanic expert was not so greatly shocked by the tech implementation on the Titan and his initial dive to refuse going on another dive in the sub.

The list of dev partners in the press release indicates OceanGate was working with or at least claiming to be working with some top talent for composite construction. Janicki, ElectroImpact, and Toray are not small time operations.

NASA and Boeing have disavowed any significant contributions to the Titan project - I wonder if they previously sent cease and desist notices to OG or were they fine to have a little shine thrown their way with a claimed connection to the novel sub design while everything was going fine with the Titan. Their names alone on a press release adds to the perception of proper and mature engineering.
 
It appears that Oceangate had a Space Act Agreement with NASA so there was some kind of relationship but NASA is downplaying it. Link
 
I Found a graphic with a list of lots of things that could have gone wrong with a composite material. I'm actually surprised the Titan held up as long as it did. Pick your favorite combination of flaws that could have led to disaster at that depth.

Common-defects-of-CFs_b3q8jh.png

 
Good spot Murph!
 
Just saw this video clip on Instagram. I now believe Stockton Rush truly under estimated the actual risk of the submersible design. There is a glimpse or two of him in the video, and he totally looks (looked) relaxed and jubilant to take people on a dive. He is fully confident of the equipment.

 
Keeping in mind that I have already proven once in this thread alone I don't know what I'm talking about, what's the purpose of going all-in on light-weight composites compared to over-designing the hell out of a submersible with metal? Is it purely a cost-cutting decision, or is it primarily an issue with weight?

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Why yes, I do in fact have no idea what I'm talking about
 
I have wondered about that, too. Maybe those in the know can answer. Is carbon fiber construction cheaper than steel? Titanium is probably the most costly due to material cost and fabrication cost. Weight of the sub would not be a total issue since the submersible has to use ballast to sink; therefore, less ballast would be required to descend. So would weight of the sub not be balanced against the buoyancy to set the maximum rate of ascent? Was the CF just a good sales point for making a claim for having the first/only CF hulled submersible?
 
I've just seen a highly speculative video suggesting that the Polar Prince may have towed the Titan out to the Titanic site on its launch platform/barge, rather than carrying it on deck. That certainly raises an eyebrow for me, and could possibly have put additional stress and shock loads on the hull as it pitched and rolled on the ocean for an extended period. There would also be shock loads from the tow line snatching occasionally due to slack forming from the motion of the sea. The launch platform certainly doesn't look suitable for extended ocean towing, in my opinion.

Looking at images of the Polar Price (and CCGS Sir Humphrey Gilbert, when she was in service with the Canadian Coastguard), she doesn't have a lot of deck space, and the small deck crane which seems to have replaced her original derrick doesn't look terribly big for lifting a 10 tonne sub and launch platform. Did she have the space and capability to properly handle the Titan?

It's very speculative, but some possibly important details around the operation, which makes me wonder if yet more corners were being cut.
 
It is very hard to design near neutrally buoyant non spherical deep sea submersibles in steel. I suspect material selection for an externally pressurised tube with end diaphragms will suddenly become a hot topic in materials courses for engineering degrees.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Sorry Debodine. The deficiency is probably at this end. Something about old dogs and new tricks.....

If all else fails, the paper was in ASTM STP 1383, COMPOSITE STRUCTURES: THEORY AND PRACTICE, Philadelphia, PA, October, 2000.

Regards

blakmax
 
SWcomposites and blakmax, got it! thanks for the guidance, SW. I knew it was ignorance on my part, or in this case, a brain fart.
 
Murph 9000 I believe the Titan and its launch platform barge were purposefully designed to be towed to any launch site. The platform submerged to launch the Titan and refloats itself with the Titan on board for recovery. Thus it is a pretty innovative LARS - Launch And Recovery System. This is not necessarily a bad concept. It eliminates the need for the support ship to have to have the large crane/ gantry typically needed for lifting ang winching the sub out of the ocean and reduces some safety risks with vertical lift ops. Certainly, it adds other safety risks amd complicates maintenance and crew loading/egress, etc., but those were deemed more manageable for the total mission profile for Titan.
 
For shorter journeys, coastal and inshore waters, towing it on the barge is fine. For hundreds of miles out into the ocean, through 8 to 10 foot waves, that's putting a lot of unnecessary stress on the submersible and barge.

Have you ever been hit head on by a wave that's 10+ feet tall, or buried the nose of a small craft into the trough of a large wave? There's a tremendous force to it, water is not gentle when it hits at 10 knots+.

The concept of sinking the barge down to around 10m before launching the sub is a good one, to avoid needing to maneuver the sub on the lumpy surface of the ocean. It's the hundreds of miles with it getting tossed around and pounded by the surface action that concerns me.
 
1503-44 said:
Polar Prince Technical details
Click to expand...

That's the wrong ship, and a far more capable support ship. The ship used by OceanGate was the former CCGS Sir Humphrey Gilbert, a multi-role coastguard icebreaker, buoy tender, and lighthouse support vessel built in 1959. IMO number 5329566.

Some photos of her over the years:
 
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