A propulsion device for a marine vessel includes a driving source including at least one electric motor, a propeller including blades with changeable pitches and rotatable around a central axis of a propeller shaft together with the propeller shaft, a propeller shaft rotation driver to transmit a driving force from the driving source to the propeller shaft and rotate the propeller shaft around the central axis, and a pitch change driver to transmit the driving force from the driving source to the blades and change pitches of the blades. The propeller shaft rotation driver includes a first shaft, and the pitch change driver includes a second shaft closer to a bow side of the marine vessel than the first shaft.

A marine propulsion unit has at least one motor for rotating a pitchable propeller around an axis. The pitchable propeller is connected with a first shaft and a second shaft, the first shaft being rotated by a first power way and the second shaft being rotated by a second power way. The first power way and the second power way are controllable independently of each other so that a first rotation speed (rpm) of the first shaft and a second rotation speed (rpm) of the second shaft can vary in relation to each other. A coupling is arranged between the first shaft, the second shaft and the pitchable propeller for changing a pitch angle of the pitchable propeller when the first rotation speed and/or second rotation speed vary in relation to the other.

A marine propulsion unit has at least one motor for rotating a pitchable propeller around an axis. The pitchable propeller is connected with a first shaft and a second shaft, the first shaft being rotated by a first power way, the second shaft being rotated by a second power way. The first power way and the second power way are controllable independently of each other so that a first rotation speed (rpm) of the first shaft and a second rotation speed (rpm) of the second shaft can vary.

A blade pitch control system for a cycloidal marine propulsion system is provided. The cycloidal marine propulsion system comprises a rotating wheel, and a plurality of rotating blades attached to the rotating wheel and individually rotatable with respect to the rotating wheel. The blade pitch control system comprises at least one rotating wheel position sensor, configured to provide a sensor signal indicative of a measured position of the rotating wheel, a wheel position estimation unit, configured to determine an estimated position of the rotating wheel based upon the sensor signal of the at least one rotating wheel position sensor, and a blade pitch determining unit, configured to determine a blade pitch set point for at least one of the plurality of rotating blades based upon the estimated position of the rotating wheel. Determining the estimated position of the rotating wheel comprises a data processing activity of the sensor signal.