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. In the preferred embodiment, 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.

A propeller (1) and a respective use method are described, comprising a cylindrical casing (3), a hub (2) couplable to an engine and rotatably mounted at least partially in the cylindrical casing of the propeller, and at least one blade (4) rotatably pivoted to the cylindrical casing. The hub (2) is rotatable with respect to the cylindrical casing of the propeller, or vice versa, to adjust the fluid dynamic pitch of the at least one blade (4). The propeller further comprises at least one elastic element (8) interposed between the hub (2) and the cylindrical casing (3) and it is characterized in that the elastic element (8) is preloaded to prevent its deformation until the resistant torque opposing the propeller rotation is lower than the torque generated by the preload of the elastic element (8), wherein said at least one blade is arranged on at least one first fixed fluid dynamic pitch before the deformation of the elastic element (8) begins. It is further described a flat spring (100) for propellers, which has a longitudinal development line (MS) and comprises a plurality of notches (103) transversally arranged with respect to the longitudinal development line. At least two distances (MD) between successive notches (103) are different from one another and/or at least two notches (103) are different from one another.

A Pulsed Locomotor (120), for propelling media, fluids and crafts, in fluids and on land, comprising a blade (124) securely connected to a drive shaft (122). Upon reciprocation, the ambient medium is forced towards the trailing edge of the blade (124) thereby causing a reactive locomotion of the apparatus, substantially along the plane of the blade. Apparatus is secured to motor M by fastening through aperture (130). The apparatus can be operated directly by motor M, and indirectly by the reaction momentum imparted to a supporting platform P. Thrust is directed by steering handle (128) about a bearing (126), rotatably coupling to platform P and base C. Lubricant L is supplied to outlets (134) via conduit (136) and inlet (132), to coat the apparatus with a lubricant cavity, for drag reduction. The blade (124) planes along a figure 8 reciprocation path s1e1s2e2s1. Crafts are embodied.

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. In the preferred embodiment, 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.

The present invention relates to a controllable pitch propeller capable of changing a blade pitch according to the sailing conditions of a ship and, specifically, to a controllable pitch propeller having an optimal hub-to-tip diameter ratio, the propeller being capable of reducing the size of a hub so as to have a high efficiency that is close to the propulsion efficiency of a fixed pitch propeller (FPP). In order to accomplish the aforementioned objective, the present invention relates a controllable pitch propeller which comprises a hub mounted at the propelling shaft of a ship, and a blade that is mounted at the circumference of the hub and that has a variable pitch, and which is technically characterized by a H/D ratio, of diameter (H) of the propeller and diameter (D) of the hub, of 0.170-0.2.

A propulsion device for a marine vessel includes a driving source including at least one electric motor, a propeller including blades with changeable pitches and rotatable around a central axis of a propeller shaft together with the propeller shaft, a propeller shaft rotation driver to transmit a driving force from the driving source to the propeller shaft and rotate the propeller shaft around the central axis, and a pitch change driver to transmit the driving force from the driving source to the blades and change pitches of the blades. The propeller shaft rotation driver includes a first shaft, and the pitch change driver includes a second shaft closer to a bow side of the marine vessel than the first shaft.

A variable pitch propeller is described, including an external central body and a plurality of rotatable blades, protruding from the central body, the central body housing, in its interior, a hub of a drive shaft which is placed coaxial to the hub, the central body housing in its interior a device to transform, in an automatic manner, the rotary motion of the hub or of the drive shaft into rotary motion of the at least one blade around its axis with respect to the body of the propeller, the device being coupled to at least one of the blades and to the hub or to the drive shaft. The device is a modified Scottish yoke kinematic system contained inside the central body.

A propeller pitch adjustment assembly is provided with a base hub operatively connected by blade shafts to propeller blades in which each blade rotates about an axis of each shaft. Each blade shaft is radially disposed about a propeller drive shaft and parallel to a pressure flange of a base hub spring plate. The spring plate counterforces the blade rotation with a lever screw that impacts the plate. An opposing spring transfers a load to the plate. The equilibrium position of the plate is determined by the spring force on the lever and a counteracting force exerted on the lever by a lift force generated by fluid flow over a propeller blade. A capping mechanism can provide a preload to the spring. A force exerted by the lift of the blade on the lever screw results in a blade pitch change.

A propeller (1) and a respective use method are described, comprising a cylindrical casing (3), a hub (2) couplable to an engine and rotatably mounted at least partially in the cylindrical casing of the propeller, and at least one blade (4) rotatably pivoted to the cylindrical casing. The hub (2) is rotatable with respect to the cylindrical casing of the propeller, or vice versa, to adjust the fluid dynamic pitch of the at least one blade (4). The propeller further comprises at least one elastic element (8) interposed between the hub (2) and the cylindrical casing (3) and it is characterized in that the elastic element (8) is preloaded to prevent its deformation until the resistant torque opposing the propeller rotation is lower than the torque generated by the preload of the elastic element (8), wherein said at least one blade is arranged on at least one first fixed fluid dynamic pitch before the deformation of the elastic element (8) begins. It is further described a flat spring (100) for propellers, which has a longitudinal development line (MS) and comprises a plurality of notches (103) transversally arranged with respect to the longitudinal development line. At least two distances (MD) between successive notches (103) are different from one another and/or at least two notches (103) are different from one another.

A propeller and related method for adjusting the fluid-dynamic pitch of the propeller blades are described. The propeller has at least one rotatable blade pivoted to a propeller cylindrical casing, a hub adapted to be coupled to an engine and mounted within the propeller casing. The hub is rotatable with respect to the propeller cylindrical casing, or vice versa, for a non-zero angular interval () for the adjustment of the fluid-dynamic blade pitch. Moreover, the hub has a contact surface movable between direct or indirect disengagement and engagement positions with a respective abutment which defines a limit stop of the angular interval (). The limit stop abutment has a region of a movable element arranged in a seat of the propeller cylindrical casing for modifying the limit stop abutment position of the at least one angular interval ().