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 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 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.

Disclosed herein is an inventive dual propeller assembly that can be manually or automatively assembled and includes a leading propeller, and a trailing propeller which are coaxially aligned and secured with a propeller shaft and a locking nut. Various embodiments are disclosed with and without interior grooves for alignment. In all embodiments, the two propellers are secured and aligned with a propeller shaft and locking nut assembly.

A propulsion unit for a marine vessel is adapted to receive power from at least one power supply unit. The propulsion unit includes a stationary part adapted to be mounted to a hull of the marine vessel, and a movable part comprising one or more thrust generating devices adapted to transform the received power into a thrust by acting on water carrying the marine vessel. The propulsion unit is adapted to receive exhaust gases from at least two internal combustion engines, wherein the movable part is adapted to release the exhaust gases into the water.

A system for providing marine propulsion is provided including an input shaft driven by a prime mover, a pinion gear coupled to the input shaft, a plurality of planet gears coupled to the pinion gear, a planet carrier having the plurality of planet gears rotationally mounted thereto, and a ring gear surrounding the planet gears and coupled thereto. The planet carrier and ring gear are coupled to internal and external output shafts that are coaxially aligned, which are coupled to aft and forward propulsor elements. The ring gear and planet carrier rotate in opposite directions to provide contra-rotating forward and aft propulsor elements. The ring gear and planet gear are each coupled to rotation altering devices that, when at least one is activated, the rotation of both the planet carrier and ring gear will be altered, thereby altering the rotation of the propulsor elements.

Example transmissions for rotating coaxial drive shafts in opposite directions are described herein. An example apparatus includes a first face gear coupled to a first drive shaft, a first elliptically interfacing gear coupled to a second drive shaft and facing toward the first face gear, the second drive shaft disposed within and coaxially aligned with the first drive shaft, and a wobble plate disposed between the first face gear and the first elliptically interfacing gear. The wobble plate has a second face gear on a first side of the wobble plate engaged with the first face gear and a second elliptically interfacing gear on a second side of the wobble plate engaged with the first elliptically interfacing gear. The wobble plate is to rotate the first face gear and the first elliptically interfacing gear in opposite directions.

A marine drive includes an output gear including a beveled gear and a hub. A propeller shaft extends through the hub. A first bearing and an adjacent second bearing are located on the hub and support rotation of the output gear. The first and second bearings have inner races and outer races. An inner spacer is located on the hub and sandwiched between the respective inner races of the first and second bearings. An outer spacer is sandwiched between the respective outer races of the first and second bearings. A bearing carrier surrounds the propeller shaft and holds the first and second bearings therein by way of a press fit. The inner and outer spacers and the bearing carrier are dimensionally sized to provide a dimensional preload on the first and second bearings to maintain the output gear in alignment with the propeller shaft during operation of the marine drive.

Disclosed herein is an inventive dual propeller assembly that can be manually or automatively assembled and includes a leading propeller, and a trailing propeller which are coaxially aligned and secured with a propeller shaft and a locking nut. Various embodiments are disclosed with and without interior grooves for alignment. In all embodiments, the two propellers are secured and aligned with a propeller shaft and locking nut assembly.

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 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.