SHIP'S PROPULSION UNIT

The invention relates to a ship's propulsion unit comprising a closed liquid cooling system (9) having an inner space (10) containing liquid. The inner space (10) is partly limited by a cylindrical outer surface (8) of a cylindrical section (7) of a motor housing section (6) of the propulsion unit for exchanging thermal energy between an electric motor (3) arranged in the cylindrical section (7) of the motor housing section (6) and liquid in the inner space (10). The inner space (10) of the closed liquid cooling system (9) is partly limited by the shell structure (1) of the propulsion unit so that liquid in the inner space (10) is in direct contact with the shell structure (1) of the propulsion unit for exchanging thermal energy between liquid in the inner space (10) and water surrounding the propulsion unit via the shell structure (1) of the propulsion unit.