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.