Patent ID: 6010380
Filing Date: 2000-01-04
Classification: B63H,F01N,F02B

Abstract:
In a marine propulsion system for a vessel adapted to travel on ambient water and having an engine that emits exhaust gas, a propeller shaft for rotating a propeller having a hub and blades extending radially from the hub, and a propeller-shaft-supporting lower unit having an outer casing with port and starboard sides disposed forward of the propeller, the improvement comprising:a) exhaust passage means within the lower unit for conveying exhaust gas down to a level corresponding to the propeller shaft level;b) a least one exhaust gas vent to ambient water located on the port side of the casing and at least one exhaust gas vent to ambient water located on the starboard side of the casing, the vents being in communication with the exhaust passage means and being located at said propeller shaft level so as to discharge exhaust gas substantially symmetrically about the propeller hub as the vessel moves forward at low velocity, the communication being patent at all rotational speeds; andc) at least one drain hole in communication with the exhaust passage means and being so located as to enable substantially complete drainage of the exhaust passage when the lower unit is not immersed.