[madphilosopher]

A flywheel has a lot of angular momentum. Of course, that's the point. On buses, the axis of the flywheel is oriented in the vertical axis so that the bus can turn corners or change horizontal directions without causing gyroscopic precession. But on a ship that pitches and rolls, the external force on the flywheel will cause a torque that changes the direction of the angular momentum of the flywheel. A roll would do something like pitch the ship forward or backward (depending on the direction that the flywheel spins), which would really mess up the ship's motion, I imagine. The preceding is just my thought experiment on what would happen to such a ship. Let's build one!