There is described an assembly having a plurality of screws, a propeller and a related method for adjusting the fluid dynamic pitch of the blades of the propeller. The propeller has at least one blade pivoted rotatably to a cylindrical propeller casing, a hub coupled to an engine and mounted coaxially inside the propeller casing, a kinematic mechanism coupled to the hub and/or to the propeller casing, and to the blade for adjusting the fluid dynamic pitch of the propeller. The hub is rotatable with respect to the cylindrical propeller casing, or vice versa, for at least one non-zero angular interval () of operation of the kinematic mechanism for adjusting the fluid dynamic pitch and is also integral with a contact surface movable between disengagement from and engagement with, direct or indirect, at least one relative abutment integral with the cylindrical propeller casing which defines a limit stop of the angular interval (). The plurality of screws has at least two different screws and the propeller has a seat for complete installation of a screw selected from the plurality of screws, and the limit stop abutment has a region of screw selected from the plurality of screws installed in the seat provided in the propeller.

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.