Consider this thing displaces about 5 m^3 of water, you’d want it to be buoyant after dropping the ballast, so the entire vehicle needs to weigh in at under 5000 kg. You’ve got 400kg of humans, and probably another 600kg of batteries and other equipment.
That means you need your pressure vessel to be under 4000kg. To fashion a 151cm OD cylinder, that was 252cm long, with spherical end caps out of titanium that was 10cm thick you’d need (if my math is correct) a weight of 7,853 kg. That would sink to the bottom of the ocean floor, which is decidedly unattractive.
Probably weight too.
Consider this thing displaces about 5 m^3 of water, you’d want it to be buoyant after dropping the ballast, so the entire vehicle needs to weigh in at under 5000 kg. You’ve got 400kg of humans, and probably another 600kg of batteries and other equipment.
That means you need your pressure vessel to be under 4000kg. To fashion a 151cm OD cylinder, that was 252cm long, with spherical end caps out of titanium that was 10cm thick you’d need (if my math is correct) a weight of 7,853 kg. That would sink to the bottom of the ocean floor, which is decidedly unattractive.