I usually implement this kind of drivetrain in lego ships. the shaft rises above the water level and is driven down to the screw with two sets of bevel gears behind the hull so I don't have to deal with watertight bearings, but the screw has fixed axis. Next time, I'll try to make the azimuth thrusters
So, what design changes did you make and how much did you improve performance? You should show off those technical skills by demonstrating and describing how and why your systems are good.