For ships that have turbo-electric drive trains rather than big shafts, I wonder if it would be possible to vector the propellers somewhat for better maneuverability, the same way that rockets use gimballing engines? Probably not worth the maintenance though, with sealant and salt water considerations.
This is common on cruise ships. They spend so much of their time going in and out of port the extra manoeuvrability is worth it in requiring fewer tugs.
Something that people perhaps don't appreciate is that typical large ships like this don't even have a gearbox (which would be perhaps 95% efficient).
They use large two stroke diesel engines which can be stopped and started in reverse. They use an extra valve in the engine head to admit air for starting and have valve gear which controls the direction.
Cruise ships on the other hand have electrical house loads which are almost the same as their propulsion loads. In addition to the manoeuvrability advantages this makes diesel electric drive advantageous.
It's not uncommon for ships to have thrusters that can move or rotate the ship in any directions. When doing underwater operations the ship needs to stay in place, and eg. GPS and/or triangulation from land or oil rigs is used to make sure it holds the correct position, even in quite strong winds.
