We'll probably have to wait for the inquiry, for the full details but yeah, it was such a weird design, normally subs have ballast tanks they fill to submerge and then purge with high pressure air to achieve positive buoyancy, it looks like all the working parts were in that fairing astern, but it didn't look big enough for any ballast tanks.
I'm wondering if the weight of the Titanium end caps was equalled by the positive displacement of the air filled pressure chamber, which made it neutrally buoyant and they just used external ballast to make it sink.
The thrusters didn't look big enough to maneuver, look at the thrusters on Alvin, they're big, not like the ones Rush had.
I know there were external ballast they could drop, Rush was using cast iron pipes and bags of steel shot, but the thing was so poorly balanced according to Karl Stanley, Rush made the passengers line up along one side of the sub when they dropped the external ballast to prevent it from rolling over as the center of gravity changed.
There were no seats or anything to secure people in place in the event of anything going wrong, you'd have been thrown around like coffee beans in a grinder.
I'm not sure why anyone trusted a cylindrical pressure chamber either, especially one made from an untested material like carbon fiber that any materials scientist will tell you is not good under compression, every expert I've seen interviewed about DSV's, from Stanley, to Cameron, to Ballard and Jaque Picard, who first took Trieste to Challenger Deep, said pressure vessels are round, as close as you can get them (Limiting Factor is titanium machined to 1000's of a millimeter tolerances) as that's the best shape to resist that ungodly pressure.
Rush's Fleshligh looked like a tube of toothpaste, and probably performed the same function when it collapsed.
