Patent ID: 7186157

Claim:
A rotatable propeller drive ( 1 ) for a boat in which said propeller drive ( 1 ) comprises: an upper fixing plate ( 4 ) adapted for rotationally fixed attachment to the hull bottom ( 2 ) of a boat and a lower underwater housing ( 6 ) on which at least one propeller ( 10 , 10 a , 10 b ) is mounted, said underwater housing ( 6 ) being rotatably mounted at the fixing plate ( 4 ) about an essentially vertical axis of rotation ( 8 ); an exhaust duct ( 50 ) provided with an exhaust exit ( 14 ) located in the underwater housing ( 6 ), wherein the exhaust duct ( 50 ) includes: an upper duct section ( 54 ) which extends through the fixing plate ( 4 ) and has an outlet opening ( 62 ) located in proximity to an opposite inlet opening ( 60 ) in a lower duct section ( 56 ) which extends through the underwater housing ( 6 ), where one of said outlet opening ( 62 ) and said inlet opening ( 60 ) overlaps the other at least within a limited first rotation angle range for the propeller drive ( 1 ), and wherein said outlet and inlet openings ( 62 , 60 ) are offset from said vertical axis of rotation ( 8 ); and said exhaust duct ( 50 ) further comprises a sliding seal arrangement ( 58 ) adapted for sealing between said upper duct section ( 54 ) and said lower duct section ( 56 ), wherein said sliding seal arrangement ( 58 ) comprises a sealing element ( 64 ) accommodated in a seat ( 66 ) around one of said outlet opening ( 62 ) and said inlet opening ( 60 ), which sealing element ( 64 ) has a contact surface ( 68 ) slidingly contacting an opposite sliding seal surface ( 70 ) around the other of said outlet and inlet openings ( 62 , 60 ).