“...No electricity to run the pumps to evacuate the ballast tanks. ... we have divers that can go 230 feet down but not for long, since the decompression takes hours. ...”
Ballast tank blow used to be performed by compressed air, held in reserve tanks. Worked faster than pumps, less prone to malfunction, doesn’t require electrical power as long as manual valve operation is possible by backup means. I stress “used to be” - haven’t checked into sub design & construction for some time.
Rigid dive suits capable of going to depths of 1000 feet or more have been in operation for decades. Think of spacesuits, in reverse.
This boat was built by a German yard but has been in the Argentine fleet for some 30 years and is the youngest sub they have. Anything is possible after such a long time in the hands of a Third World country.
Zere is nussing wrong wit ze German engineerink!.....................
Saw a doc on the USS Thresher. One of the theories was that the Thresher had rigid screens over the emergency tank nozzles, and given expanding air sucking the heat out of a moist environment, the screens iced up, blocking, then clogging the nozzles.
From my scuba days, I remember regulator companies hyping transferring heat from exhaled breath to the regulator internals. (Granted, regulators claimed to be designed to fail "open" anyway.)