Abstract: A boat comprising a propeller tunnel formed in a hull. The tunnel has a forward end and a rearward end. The rearward end defines a shaped upper surface transverse to a longitudinal axis of the propeller tunnel. An output shaft extends from the propeller tunnel. A propeller is provided that rotates on the output shaft and comprises a plurality of blades defining: outer diameter and radius dimensions, a forward plane perpendicular to the output shaft and defined by a forward-most extension of said blades, and an aft plane perpendicular to the output shaft and defined by an aft-most extension of the blades. A protrusion is provided terminating aft of the propeller and inwardly extending from the propeller tunnel. The protrusion defines a curved portion that terminates in a tip portion, wherein a longitudinal distance between the tip portion and the aft plane is less than the outer diameter dimension.

Abstract: A boat including a propeller tunnel portion formed in a hull of the boat in which a propeller rotates on an output shaft that extends from the propeller tunnel. A protrusion having a curved portion terminates in a tip portion. The protrusion extends from the propeller tunnel portion and the tip portion terminates near the aft plane of the propeller. The placement of the protrusion in the propeller tunnel portion can be shown to improve propulsion efficiency.

Abstract: A boat including a propeller tunnel portion formed in a hull of the boat in which a propeller rotates on an output shaft that extends from the propeller tunnel. A protrusion having a curved portion terminates in a tip portion. The protrusion extends from the propeller tunnel portion and the tip portion terminates near the aft plane of the propeller. The placement of the protrusion in the propeller tunnel portion can be shown to improve propulsion efficiency.