Rotating-Blade Propeller

a marine propeller with vertical rotating wing-shaped blades spaced at equal angles around a rotor that rotates relative to its vertical axis. The rotor is driven by the main engine through a reduction gear and is mounted in a housing flush with the outer skin; only the blades protrude below the ship’s bottom into the water. There are three to seven blades; as the rotor turns, they rotate about their longitudinal axes so that each blade, like a wing, develops a thrust in the direction of the ship’s motion. The thrust is adjusted by varying the angular setting of the blades.

A rotating-blade propeller can produce thrust in any direction, so that it becomes possible to turn the ship without using the rudder, both during forward or backward motion and when motionless. The ship is maneuvered (without altering the direction and rate of rotation of the rotor) and the rotating-blade propeller is controlled from the bridge. Such propellers are used as the main drive on vessels for which maneuvering requirements are higher than usual (harbor tugs, minesweepers, floating cranes, ferryboats, and so on), and also as an auxiliary steering gear on large ships.