What is the primary means of propulsion on a ship?

The primary means of propulsion on a ship is the propeller. A propeller converts the rotational motion provided by the ship's engines into thrust, allowing the vessel to move through the water. When the engines turn the propeller, it pushes water backward, and according to Newton's third law of motion, the ship moves forward as a reaction.

Other components, like the rudder, are critical for steering and maneuverability but do not provide propulsion. The mast is primarily used for carrying sails or antennas and is not involved in the direct movement of the ship. Freeboard refers to the distance from the waterline to the upper deck level and is related to a ship's structural integrity and safety rather than propulsion. Thus, the propeller serves as the fundamental mechanism that enables a ship to transit across the waters, confirming its position as the primary means of propulsion.