The lengths and/or chords and/or pitches of wind turbine or propeller blades are individually established, so that a first blade can have a length/chord/pitch that is different at a given time to the length/chord/pitch of a second blade to optimize performance and/or to equalize stresses on the system.

A propeller device for a marine vehicle with a main shaft; a front propeller is provided on the main shaft, the front propeller having a hub and a plurality of blades extending radially outwardly from the hub; a rear propeller being co-axially to and spaced from the front propeller, the rear propeller having a hub and a plurality of blades extending radially outwardly from the hub. A second shaft being communicated with the hub of the front propeller; and at least one support for supporting the rear propeller on the second shaft, the support prevents the second shaft to rotate in the direction of rotation of the main shaft, and being free to rotate thereof in the counter direction of rotation of the main shaft.

A novel watercraft propulsion device is disclosed that includes multiple propulsive elements improving power and efficiency over prior designs. A self-adjusting variable pitch propeller is combined with a water jet and an exhaust driven turbine to provide optimal thrust and efficiency across the range of engine power, load and watercraft speed. Propulsive elements are axially disposed around a central drive shaft and exhaust port with the combined water jet/exhaust turbine disposed closest to drive shaft and the variable pitch propeller attached to the exterior of the water jet housing. A rotating duct is fixed to the propeller blades and rotates with the blades to reduce cavitation. Combined apparatus provides increased performance and efficiency over all watercraft speeds/load as well as additional safety due to the ducted propeller. Propulsor with an inducer, conical impeller and a diffuser also shown.

The present disclosure relates to a vessel propelling mechanism. In one aspect, a vessel propelling system includes a motor and a waterjet system. The waterjet system is coupled to the motor and includes a stator with a plurality of blades. A first blade of the plurality of blades has a shape that is different than remaining blades of the plurality of blades, the shape of the first blade allowing a driving mechanism of the motor to be coupled to a shaft within the waterjet system.

A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

Propulsion devices that provide increased propeller efficiency when operating outside of an optimal advance ratio are described. In one example, a propulsion device includes a hub having a curved surface extending around and along a rotation axis of the hub. The propulsion device can further include two or more rows of blades extending radially outward from the curved surface and including a first row of blades having a first blade and a second row of blades having a second blade that is angularly and axially offset from the first blade on the curved surface. A first centerline of the first blade and a second centerline of the second blade each intersect with a helical line that extends along the rotation axis of the hub. The first blade and the second blade collectively form a helical pattern of blades that projects radially outward from the curved surface along the helical line.

The lengths and/or chords and/or pitches of wind turbine or propeller blades are individually established, so that a first blade can have a length/chord/pitch that is different at a given time to the length/chord/pitch of a second blade to optimize performance and/or to equalize stresses on the system.