Would the engine going down typically kill *all* electrical immediately? I’d hope they’d at least have several minutes of battery supply for instrumentation and control.
What’re the chances this was just bad fuel into a marginally maintained engine?
Quite the contrary. Loss of electrical power would necessitate shutting down the main engine, as the lube oil pumps, cooling pumps, and scavenge air pumps are all electric motor driven.
I went up on the beach 16 years ago, so am not certain that procedures are still the same, but in my experience a ship would always have at least two generators up and paralleled before entering a port and whilst maneuvering within the port. As it would be a stretch to imagine both generator engines going down at once, I consider the possibility that the blackout might have been caused by malfunction in the switchgear, like weakened circuit breakers or thermal overloads.
Indeed, there is on board a bank of batteries that would immediately and automatically engage to supply emergency lighting, the gyro, navigation electronics, and radios, but would not be sufficient to power the steering pump AC motor.
RE: fuel, it is possible that the engine crew were switching the main engine over from MDO (marine diesel oil) to heavy oil, if the engine was already hot enough and the turbochargers were spooled up. However, the generator engines would not be affected because they continue to burn MDO.