A marine propulsion system, supported by a strut, comprising an inner propeller shaft supporting a first propeller adjacent a trailing end thereof, and the inner propeller shaft is connected to the drive shaft for receiving and supplying a first portion of torque to the first propeller as well as transfer thrust, generated by the first propeller, along the inner propeller shaft back to the drive shaft. An outer propeller shaft supports a second propeller adjacent a trailing and thereof, and the outer propeller shaft surrounds the inner propeller shaft. A differential gear set receives a second portion of the torque and supplies the second portion to the outer propeller shaft so that the second propeller rotates in an opposite rotational direction to the first propeller. The thrust, generated by the first and the second propellers, is conveyed along either the inner or the outer propeller shafts, to the drive shaft.

A strut mounted gear box for counter rotating propellers. The gear box is strut mounted for securement to the hull of a boat. A main input shaft is coupled to a propulsion component of a boat with a distal end secured to an idler gear cage assembly located within the gear box. The main input shaft transfers torque and rotation from the propulsion component to an idler gear cage assembly. An inner tail shaft is coupled to the main input shaft and arranged to rotate the inner tail shaft in a first direction. A counter shaft is coupled to the idler gear cage assembly and arranged to rotate the counter shaft in a second direction. A first propeller is secured to the inner tail shaft providing rotation in the first direction; and a second propeller is secured to the counter shaft allowing rotation in the second direction.

A floating vessel with gearless pod propulsor and counter rotating propellers is secured to a hull, each pod having a lead propeller and a trailing propeller, each propeller connected to a shaft connected to either a stator and rotor or a hydraulic motor. A lead propeller turns in a first direction and a trailing propeller turns in an opposite direction simultaneously, generating thrust for the floating vessel along a thrust vector using the counter rotation of the trailing propeller to recover swirling energy from the lead propeller improving propulsive efficiency of the floating vessel. The pod is positioned below a water line of the floating vessel providing propulsion for the floating vessel without gears.

A method controlling a thruster of a marine vehicle is provided. The marine vehicle is at least partially submerged in a liquid and includes a body and a thruster including two propellers. Each propeller includes blades intended to tum about a rotation axis of said propeller. The method includes a step of low-speed maneuver controlling, during which the thruster is controlled in such a way that each propeller generates a flow directed toward the flow generated by the other propeller and reaching the flow generated by the other propeller.

A method controlling a thruster of a marine vehicle is provided. The marine vehicle is at least partially submerged in a liquid and includes a body and a thruster including two propellers. Each propeller includes blades intended to tum about a rotation axis of said propeller. The method includes a step of low-speed maneuver controlling, during which the thruster is controlled in such a way that each propeller generates a flow directed toward the flow generated by the other propeller and reaching the flow generated by the other propeller.

A front propeller on a main shaft communicated from one end to an engine transmission; the propeller having a hub and a plurality of blades extending radially outwardly from the hub; a rear propeller co-axially to, and spaced apart from, the front propeller rearwardly in an axial direction having a hub and a plurality of blades extending radially outwardly from the hub. An adaptor is coaxial with the main shaft and comprising a second shaft for supporting the rear propeller. A plurality of pitched-formed seating surfaces having ramps, are spaced apart from the second shaft in an axial direction. An adaptor communicates with the rear side of the front propeller in the axial direction; a plurality of locking elements are movable in the axial direction, each being in contact with the seating surfaces of the adaptor, and communicate with the rear propeller from the other end.

Provided is a ship propelling apparatus including a rotation shaft on which a rear propeller is fixed; a front propeller rotatably supported on the rotation shaft in front of the rear propeller; and a counter-rotating device through which the rotation shaft passes, which includes a gear box including therein a plurality of gears configured to reverse rotation of the rotation shaft and transfer the reversed rotation to the front propeller, and which is installed in an installation space formed at the rear of a ship. The rotation shaft includes a measurement hole formed to pass through a center of the rotation shaft for centering of the counter-rotating device installed in the installation space; and an individual lubricant path separated from the measurement hole.

Provided is a ship propelling apparatus including a rotation shaft on which a rear propeller is fixed; a front propeller rotatably supported on the rotation shaft in front of the rear propeller; and a counter-rotating device through which the rotation shaft passes, which includes a gear box including therein a plurality of gears configured to reverse rotation of the rotation shaft and transfer the reversed rotation to the front propeller, and which is installed in an installation space formed at the rear of a ship. The rotation shaft includes a measurement hole formed to pass through a center of the rotation shaft for centering of the counter-rotating device installed in the installation space; and an individual lubricant path separated from the measurement hole.

Transmission systems and methods are for a marine propulsion device having an internal combustion engine that drives a propulsor. An input shaft is driven into rotation at a non-zero first rotational speed by the internal combustion engine. An output shaft drives the propulsor into rotation at a non-zero second rotational speed. A planetary gearset transfers power from the input shaft to the output shaft. A band brake is on the planetary gearset. Actuation of the band brake effects a gear change in the planetary gearset. A band brake actuator actuates the band brake to effect the gear change. A controller controls the band brake actuator. Based upon one or more operational characteristics of the marine propulsion device the controller is programmed to control the band brake actuator so that the second rotational speed is less than the first rotational speed.

Transmission systems and methods are for a marine propulsion device having an internal combustion engine that drives a propulsor. An input shaft is driven into rotation at a non-zero first rotational speed by the internal combustion engine. An output shaft drives the propulsor into rotation at a non-zero second rotational speed. A planetary gearset transfers power from the input shaft to the output shaft. A band brake is on the planetary gearset. Actuation of the band brake effects a gear change in the planetary gearset. A band brake actuator actuates the band brake to effect the gear change. A controller controls the band brake actuator. Based upon one or more operational characteristics of the marine propulsion device the controller is programmed to control the band brake actuator so that the second rotational speed is less than the first rotational speed.