How they make propeller shafts on large vessels like ocean liners or aircraft carriers waterproof considering the intense water and mechanical pressures that come into play?

Question

It seems like a grommet-type seal would fail in no time. Also, looking at an image of one of the propellers for the Queen Mary, it hit me that this is decades old, and would have to go to dry dock to be serviced, and there is no way they are doing that so… How is that even possible? I’d figure dry rot would set in somewhere along the way.

In: Engineering

Answer 1

Traditionally propeller shafts were sealed with a stuffing box. These were crammed with oiled rope to form a tight, waterproof but relatively low-friction seal. Modern boxes use more modern fibers than ropes of old but the concept is much the same.