“Once the vessel’s weights dissolved after 24 hours, the submersible would be able to rise to the surface.”
WHAT!!??.....UNBELIEVABLE.
24+ hours under constant 5000psi, and the weights would not be the only thing to ‘dissolve’...............
It is a backup system in case the primary electronic weight control system fails. The tethers that hold the weights in place dissolve in ocean water after 24 hours and drop the weights.
I don’t know how you could possibly improvise on the ocean floor and use “hydraulics” to drop the weights.