There is provided a ship propulsion machine including: a drive shaft; a drive gear fixed to the drive shaft; a front gear meshed with the drive gear; a rear gear meshed with the drive gear; a rear propeller provided on an inner propeller shaft; a front propeller provided on an outer propeller shaft; a casing having a gear chamber; a second bearing that supports a front end side of the outer propeller shaft at a rear portion of the casing; a third bearing that supports the inner propeller shaft and the outer propeller shaft in a manner rotatable with respect to each other. The third bearing is disposed on an inner peripheral side of a shaft portion of the rear gear, and the second bearing is disposed on an outer peripheral side of the shaft portion of the rear gear.

A drive system is provided for propelling a ship through water. The drive system has two propellers. The propellers are coaxial so that one propeller engages the incoming water first, and the other propeller engages the water after it passes through the first propeller. The drive system has a stator that causes a first rotor to rotate. The first rotor is connected to, the first propeller to cause the first propeller to rotate. The first rotor also causes a second rotor to rotate. The second rotor is connected to the second propeller to cause the second propeller to rotate.

A drive system is provided for propelling a ship through water. The drive system has two propellers. The propellers are coaxial so that one propeller engages the incoming water first, and the other propeller engages the water after it passes through the first propeller. The drive system has a stator that causes a first rotor to rotate. The first rotor is connected to, the first propeller to cause the first propeller to rotate. The first rotor also causes a second rotor to rotate. The second rotor is connected to the second propeller to cause the second propeller to rotate.

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.

There is disclosed a marine propulsion system for a shaft-driven boat. The system includes a recess formed in the hull of the boat, and a drive cassette. The drive cassette includes: a housing; a static tube extending rearwardly from the housing and fixed relative thereto; and at least one drive shaft extending through the static tube and into the housing. The drive shaft is supported for rotation within the static tube by at least one shaft bearing, and is rotatably supported within the housing by thrust bearings. The static tube, the drive shaft, the or each shaft bearing, and the thrust bearings are all coaxially aligned with one another. The housing and the recess are mutually configured such that the housing may be engaged within the recess to install the drive cassette within the drivetrain of the boat.

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.

There is disclosed a marine propulsion system for a shaft-driven boat. The system includes a recess formed in the hull of the boat, and a drive cassette. The drive cassette includes: a housing; a static tube extending rearwardly from the housing and fixed relative thereto; and at least one drive shaft extending through the static tube and into the housing. The drive shaft is supported for rotation within the static tube by at least one shaft bearing, and is rotatably supported within the housing by thrust bearings. The static tube, the drive shaft, the or each shaft bearing, and the thrust bearings are all coaxially aligned with one another. The housing and the recess are mutually configured such that the housing may be engaged within the recess to install the drive cassette within the drivetrain of the boat.

A propeller drive assembly for transferring a torque between an engine and at least one propeller of a water surface vessel includes a plurality of lubrication clients. The propeller drive assembly includes a first lubrication system arranged to house a first lubricant, dedicated for lubrication of at least one first of the lubrication clients, and a second lubrication system arranged to house a second lubricant, dedicated for lubrication of at least one second of the lubrication clients, the at least one second lubrication client includes a seal arranged to seal the second lubrication system from a body of water surrounding at least a portion of the propeller drive assembly, the second lubrication system being arranged to transport the second lubricant to the seal.

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.