Hollow hub marine propeller with anticavitation groove

Claim 2

A marine propeller having a hub with a hollow interior passage terminating at a rearwardly located discharge opening for passage of exhaust gases into the water and with a plurality of propeller blades extending outwardly from said hub spacedly forwardly of said opening, said hub rearwardly of said blades having a smooth outer surface extending in the direction of normal water flow during straight ahead high speed propulsion, said propeller being characterized by a hub-girdling groove disposed spacedly between said blades and said rearward opening, said groove opening outwardly through said hub surface and defined by a rear groove wall, said groove having a bottom located inwardly of said surface and said rear wall extending outwardly from the bottom of said groove toward said surface at an angle with respect to the hub axis not greater than 90° as measured in a forward direction.

Claim 3

A marine propeller in accord with claim 1 wherein more than one such groove is located along the portion of said hub surface between said blades and said rearward opening.

Claim 4

A marine propeller in accord with claim 1 wherein said groove rear wall extends circularly around said hub.

Claim 5

A marine propeller in accord with claim 1 wherein said groove defines a helix of at least one full turn around and along said hub.

Claim 6

A marine propeller in accord with claim 1 wherein said groove is rectangular in cross section.

Claim 7

A marine propeller in accord with claim 3 wherein said groove is rectangular in cross section.

Claim 8

A marine propeller in accord with claim 4 wherein said groove is rectangular in cross section.

Claim 9

A marine propeller in accord with claim 1 wherein the upper end portion of said rear wall is in the form of a forwardly extending annular lip partially closing the entrance into said groove.

Claim 10

A marine propeller in accord with claim 8 wherein said lip tapers in cross section forwardly from said rear wall.

Claim 11

A marine propeller in accord with claim 8 wherein said lip is resilient.

Claim 12

A marine propeller in accord with claim 8 wherein said groove is defined by a front wall lying in a plane normal to the hub axis.

Claim 13

A marine propeller in accord with claim 1 wherein said wall is of resilient material.

Claim 14

A marine propeller in accord with claim 1 wherein the width of the opening through said surface into said groove is less than the maximum width of said groove inwardly of said surface.

Claim 15

A steerable marine propeller having a hub with a hollow interior passage terminating at a rearwardly located discharge opening for passage of exhaust gases into the water and with a plurality of propeller blades extending outwardly from said hub spacedly forwardly of said opening, said hub rearwardly of said blades having a fair outer surface extending in the direction of normal water flow during straight ahead high speed propulsion, said propeller being characterized by means defining an annular cavity girdling said hub having a bottom disposed inwardly of said surface and opening outwardly through said outer surface of said hub, said means including rear wall extending outwardly from said bottom, said cavity being operative to receive water thereinto through said opening at one side of the hub when the hub is subjected to water flow toward such side, such as during steering, and to release water so received from the cavity on the opposite side of the hub.

Claim 16

A steerable marine propeller having a hub with a hollow interior passage terminating at a rearwardly located discharge opening for passage of exhaust gases into the water and with a plurality of propeller blades extending outwardly from said hub spacedly forwardly of said opening, said hub rearwardly of said blades having a fair outer surface extending in the direction of normal water flow during straight ahead high speed propulsion, said propeller being characterized by means defining an annular cavity girdling said hub having a bottom disposed inwardly of said surface and opening outwardly through said outer surface of said hub, said means including rear wall extending outwardly from said bottom, said cavity being operative to receive water thereinto through said opening at one side of the hub when the hub is subjected to water flow toward such side, such as during steering, and to release water so received from the cavity on the opposite side of the hub.

Claim 17

A marine propeller in accord with claim 14 wherein said cavity has a closed bottom and a rearward end wall and is in part defined inwardly of an annular lip extending forwardly from said rearward end wall, said lip having an outer surface substantially fair and flush with said outer surface of said hub, said lip terminating forwardly in an edge defining the rearward side of such opening.

Claim 18

A marine propeller in accord with claim 14 wherein said cavity has a closed bottom and a rearward end wall and is in part defined inwardly of an annular resilient lip extending forwardly from said rearward end wall, said lip having an outer surface when at rest substantially fair and flush with said outer surface of said hub, said lip being yieldable from its at rest shape under the forces of flowing water and terminating forwardly in an edge defining the rearward side of such opening.