There are plenty of airplanes which have only a single propeller. You can find videos online from light aircraft where the propeller literally fell off in flight.
Sub propellers have a lot of torque. There's no way that one would really get entangled by seaweed. But thick ropes, cables, and heavy fishing tackle are a risk. Every military sub carries qualified divers who could manually cut it free as a last resort.
Sub propellers have a lot of torque. There's no way that one would really get entangled by seaweed. But thick ropes, cables, and heavy fishing tackle are a risk. Every military sub carries qualified divers who could manually cut it free as a last resort.