Patent ID: 7247068

Claim:
A propulsion unit for a boat, the propulsion unit comprising a cylindrical pump housing, a rotatable impeller disposed in the cylindrical pump housing, said impeller having an upstream side and a downstream side, a plurality of stationary blades disposed within the pump housing on the downstream side of the impeller, wherein the stationary blades are provided for guiding a fluid stream in an axial direction of the pump housing, an intake structure for extracting cooling water from the pump housing and sending the cooling water to an engine, a water muffler and other water-cooled members, the intake structure disposed between a first stationary blade and a second stationary blade which is adjacent to the first stationary blade, wherein: a bisecting line bisects the space between the first stationary blade and the second stationary blade, the intake structure is provided on a part of the pump housing on a side of the first stationary blade relative to the bisecting line, and wherein the propulsion unit is constructed and arranged such that when the boat is towed while the impeller is stopped, hydraulic pressure on the side of the first stationary blade relative to the bisecting line is lowered by the guide action of the impeller, and hydraulic pressure on a side of the second stationary blade relative to the bisecting line is raised, respectively.