The arrangement comprises at least one steering electric motor (60) rotating the propulsion unit (20) via a force transmission arrangement (50). The force transmission arrangement (50) comprises a differential (100) comprising a first shaft (111) connected to the steering electric motor (60), a second shaft (131) connected to the propulsion unit (20), and a third shaft (141) connected to a brake device (200). The third shaft (141) is locked from rotation when a torque produced by an external force on the propulsion unit (20) is below a threshold value, whereby power is distributed only from the steering electric motor (60) to the propulsion unit (20) or vice a versa. The third shaft (141) is allowed to start rotating when the torque produced by the external force on the propulsion unit (20) exceeds the threshold value, whereby power is distributed from the steering electric motor (60) to the rotation of the propulsion unit (20) and to the brake device (200) or from the rotation of the propulsion unit (20) to the steering electric motor (60) and to the brake device (200).