What device is used to pump and force water through a steering nozzle on a vessel?

The correct answer, impeller, is essential in the operation of certain types of boat propulsion systems, particularly jet drives. An impeller is a rotating device that draws in water and forces it out through a steering nozzle at the back of the vessel. This high-pressure jet of water not only propels the boat forward but also allows for increased maneuverability and steering.

The other options refer to different components of a vessel's propulsion or steering system but do not perform the same function as the impeller. The drive shaft transmits power from the engine to the propeller but does not actively pump water. The stern drive combines features of both inboard and outboard motors but is not responsible for the direct movement of water through a nozzle. The transom is the rear part of the boat where the engine or motor is mounted; it supports the structure but does not play a role in pumping water. Understanding the specific roles of these components helps clarify the importance of the impeller in watercraft propulsion systems.