Marine propeller

A marine propeller having a hub and a plurality of blades each attached to the hub, said blades each comprising a body having a radially inner end connected to said hub and a radially outer tip located radially outwardly from said inner end;

• said body having an inner section located adjacent said inner end and extending outwardly therefrom which is contoured so that it has a rounded leading edge and a tapered trailing edge portion with arcuate pressure and suction side surfaces extending therebetween;
• said body having an outer section located adjacent said tip and extending radially inwardly therefrom which is contoured so that it has tapered trailing and leading edge extending therebetween, said side surfaces of said outer body section being of higher pitch than said inner section so as to give said outer section a higher angle of attack than said inner section,
• means whereby during rotation of said blade at slow speeds both sections function in a noncavitation producing manner and at high speeds said inner section continues to subcavitate and said outer section functions as a supercavitation section.

A marine propeller having a hub and a plurality of blades each attached to the hub, said blades each comprising a body having a radially inner end connected to said hub and a radially outer tip having an inner section located radially outwardly from said inner end, said blade body having an inner section adjacent said inner end with means for causing said inner section to subcavitate at substantially all rotational speeds and an outer section adjacent said tip with means for causing said outer section to supercavitate and create a cavity at high rotational speeds, said blade proportioned so that the mid-chord line for said blade extending through said tip and hub extends rearwardly and radially outwardly through said outer section at a swept back angle inclined with respect to a radial line extending perpendicular to the axis of rotation of said blade through said blade whereby radially outer flow of the liquid medium in which the propeller operates is induced to deflect the cavity on the blade outwardly away from the subcaviating inner end.

A marine propeller having a hub and a plurality of blades each attached to said hub, said blades each comprising:

• a body having a radially inner end connected to said hub, a radially outer tip, an inner section adjacent said inner end, and an outer section adjacent said tip;
• said inner section having contoured suction and pressure sides on opposite sides of said blade which cause said inner section to subcavitate at substantially all rotational speeds;
• said outer section being contoured to supercavitate at high rotational speeds and including a convex suction side and a concave pressure side on opposite sides of said blade, said suction side having a chord length greater than the chord length of said pressure side generally at each radial position along said outer section, and a trailing surface area which extends between the trailing ends of the chords on said pressure side and the trailing ends of the chords on said suction side.