I understand why oceanographers /might/ want to do this, but not in person when ROV tech is so good now, for biology and tourism. There are so many things that can happen to fragile humans in that complex machine: drowning, freezing, asphyxiating, crushing, oxygen narcosis, nitrogen narcosis, co2 poisoning, and the plain old bends.
So why do people risk all that, and pay 125k to do it? Why the titanic obsession? It's only the fourth worst maritime disaster (Doña Paz in 1987 had 4k deaths) and so what if someone made a movie about one.
That said, yes, titanic might not have been my choice personally. It has a sister ship that lies at a more reasonable depth of ~100 meters, so divers can actually be in the water and explore the inside. It is also fairly intact in contrast to titanic which is broken in half with the stern being mostly destroyed.
People enjoy casual risk-taking.
If I had the 125k to dish out for this experience, I probably would have done so myself.
An umbilical cable, copper conductors and fiber optics inside steel wire sheath. The weight of the thing makes it impossible to attach it directly to the ROV - It would be unmaneuverable - so instead they bring it down to a TMS (Tether Management System) - basically a cage where the steel umbilical terminates and a spool of lightweight tether cable, 100m or so, which the crew then pays out to give the ROV the capability to snoop around at depth.
https://en.wikipedia.org/wiki/Remotely_operated_underwater_v...
Is a great starting spot, read it and then branch out following the sources links.
As an aside, one of the first field jobs I attended after graduating was commissioning some equipment fitted onto the R/V Knorr, the very ship which was used for finding the Titanic.
For a Titanic buff, that was a great experience - doubly so when the project manager at the Woods Hole end found out that I had more than a passing interest in the wreck, and during lunch one day suggested we go see if we could find Bob, as he believed him to be on the premises.
Bob, of course, turned out to be Robert Ballard, who turned out to be an incredibly gentle and patient guy who answered each and every question I had like it was the first time he had it posed to him, despite probably having had them thousands of times before...
For high depth like this, tanks of a light liquid are probably most suitable. I'd probably use liquid butane. With a vapour pressure of 40 psi, it is easy to contain, and is has a density of only half of water. If it leaks, there won't be an environmental cleanup cost either.
https://en.wikipedia.org/wiki/Jason_(ROV)
Titanic was also discovered with a tethered sled, the Argo:
https://en.wikipedia.org/wiki/Argo_(ROV)
It was then explored with a combination DSV and tethered ROV:
The wreckage site is around 370 miles from Newfoundland, Canada.
Seems like the rescue effort could be unfolding over days.
mercifully quickly?
https://web.archive.org/web/20070202144233/http://bjsonline....
https://www.youtube.com/watch?v=29co_Hksk6o
"I couldn't help noticing how many pieces of the sub seemed... improvised."
Fix it in post
Save/load game
“We run the whole thing from this game controller.” [shows some knockoff controller]
https://www.amazon.com/Logitech-Wireless-Nano-Receiver-Contr...
and this from a review:
“Pretty good controller, fits in hand comfortably and is compatible with anything I throw at it in a Debian linux environment. The conductive pads are extremely low quality though as I've had to replace them 3 times in the 2 years Ive been using it. For a Logitech product I expect better build quality and reasonably easier to find replacement parts but not true for this product.
Last night I had the left directional button go out on me and without parts on hand I ended up breaking down an old wired controller I had laying around. The IZDTech controller i used for parts is over 5 years old and the conductive pads are still in good shape. With a little modification I was able to get them to sit 'okay' on the buttons. Until i can find the appropriate conductive pads this will have to do.”
They also briefly showed a single button on the wall that it was implied functioned like an elevator button.
There were a lot of ways it looked like things could trivially go wrong, once you got a feel for how it was built.
Can anyone even try to explain this choice? Even a hobbyist would curate the inside with top of the line products and aesthetics - this dude this dude has just jerry rigged some cheap chinese crap - what the actual hell?
It should not have a low-cost consumer-grade controller.
The CEO should not be bragging about the fact that it does, on camera. It demonstrates an incredible lack of experience and/or mental disconnect. All of this would be fine if it were a boat in an amusement park 1 meter pond or something, but it is in the open ocean at depth. It was a matter of time before people died.
> "We only have one button, it should be like an elevator."
Oof. The thought of being at that depth being at the sole mercy of automated software. Godspeed to those aboard.
I don't think they have any "drop-weights" which would make them positively buoyant. If I'm reading the spec-sheet correctly, the submersible itself weights ~1500lbs. Subs have ballast tanks which they pump with air and force out water to make themselves positively buoyant. But if something goes wrong with the mechanism to fill the ballast tanks, I'm guessing they'd just be stuck at depth. (disclaimer, I am far from an expert at this - I just have a cursory understanding of Boyle's law)
edit: upon viewing this video https://www.youtube.com/watch?v=29co_Hksk6o&t=157s they seem to have construction pipes as ballasts that they can drop :| God help the poor souls on that sub
https://en.wikipedia.org/wiki/Emergency_main_ballast_tank_bl...
It's not too much of a leap from there to the 380 bar pressure at Titanic's depth.
As such, I will revise my theory, and posit that the actual issue with this strategy at Titanic depths is keeping the water out of the ballast tanks once you've evacuated them. This seems plausible given that the hatch must be bolted on from the outside. If they had a method to keep 382 bar of water dynamically out of the ballast tanks, presumably they could use that same method to have a hatch that can be opened without manual screwing.
[1] https://steelheadcomposites.com/composite-pressure-vessels/
By filling the ballast tanks with 382 bar of air.
The human-interior of the sub is maintained at 1 bar to avoid compression demands (hyperoxic seizure triggers at approx 7.6 bar when breathing atmospheric gases; HPNS (High Pressure Nervous Syndrome) is common after 16 bar on a helium-oxygen mix), and decompression requirements.
Equalizing the inside-outside pressures would help a lot with the composite materials, and somewhat less so with the fleshy meat bags inside.
Then to clear the ballast tank you would open the air tank, the higher pressure air would then force out the lower pressure water (this is clearly why it can't be the same pressure as implied in your first comment), and then when you're done you have two tanks (your air and ballast tanks) both at 380 bar.
If that's how it works (which sounds better to me), you'd actually need a PV rated for 740 bar, which seems well outside our current materials science. Presumably you could increase the volume of the air tank relative to the ballast tank and therefore need less than 2x pressure, but the more you do that the more you're increasing your buoyancy, defeating the purpose. In fact (and I'm still mostly just spitballing here, not actually doing any math), I assume you really need some pressure greater than 2x, otherwise you're just cancelling out your ballast with your air tank. You need the volume of the air tank to be less than your ballast tank to actually end up with ballast tanks that make you sink without being totally counteracted by your purge tanks.
That would track with using this system in submersibles that are operating at ~300m and not for things like this which are trying to operate at 4000m. At 300m you could have a 400 bar COPV that is 7.5% the size of the ballast tanks, which sounds practical.
edit: No cites, sorry.
I see so many parallels to bad devops patterns I’ve seen. You build your incident response protocols around a metric alarm (bouy being released). However the alarm is noisy so people either ignore the alarm or suppress it (welding the bouy in place). And then when an actual accident occurs your response is ineffective.
Nothing can be actual human care and attention. Everything can break and no automated system made by careful people is exempt from needing that.
I'm reminded that late into development of a Pixar movie servers crashed, work was lost, and the automated back up system failed. The only thing which saved it was that an artist took a copy of the project home to work on it.
If so how do you know that?