Propellers for boats are usually of two types, left-hand and right-hand, known as CW and CCW respectively.
CW is an abbreviation for Clockwise, indicating a clockwise rotating propeller, also known as a right-hand propeller. When a ship's propeller is rotating, the leading edge of the propeller blade is to the right and the trailing edge is to the left when viewed from the side, propelling the water in the same direction as the rotation. The right-hand propeller is usually mounted on the left side of the ship, i.e. the port side of the ship.
CCW stands for Counterclockwise and indicates a propeller that rotates counterclockwise, also known as a left-hand propeller. When the ship's propeller is rotating, the leading edge of the propeller blade is to the left and the trailing edge to the right when viewed from the side, propelling the water in the opposite direction to the direction of rotation. The left-hand propeller is usually installed on the right-hand side of the ship, i.e. the starboard side of the ship.
Installing the left and right-hand propellers on both sides of the ship balances the propulsive and side thrust forces, making the ship more stable and stable.
CW propellers: produce forward thrust when rotating clockwise and backward thrust when rotating counterclockwise;
CCW propellers: produce forward thrust when rotating counterclockwise and backward thrust when rotating clockwise;