Patent ID: 8210885

Claim:
An impeller for the pump of a waterjet unit that is rotatably driven by an engine to generate a high velocity jet stream, having a thrust that is dependent on the power absorbed by the impeller, which is in turn dependent on the rating of the impeller and the engine speed, to propel a marine vessel, the impeller comprising: a hub mountable to a rotating shaft through which an input power is transmitted by the engine; and a plurality of blades spaced about the periphery of the hub, the blades having a primary profile that defines the primary rating of the impeller, each blade having a span that extends outwardly from the hub to an outer edge of the blade and a length defined between a leading edge of the blade situated toward the front end of the hub and a trailing edge of the blade situated toward the rear end of the hub, where a trailing portion of each blade has resilient flexibility relative to the primary profile such that the trailing portion will progressively flex under hydrodynamic load to alter the profile of the blades to progressively lower the rating of the impeller with increase in engine speed, the flexible trailing portion of each blade having minimal progressive flex for a substantial portion of the lower engine speed range to maintain the primary rating of the impeller, and increasing substantial progressive flex for an upper portion of the engine speed range to progressively lower the rating of the impeller from its primary rating.