Provided is a pod propulsion system including first and second counter rotating propellers for propelling a marine vessel first and second propeller modules, each including an electric motor having a driving-end configured to rotate the first and second propellers, respectively. Also included are first and second gondolas, each (i) for housing a respective one of the first and second electric motors and (ii) including a boltable interface formed along a lengthwise direction of an extremity of the gondola. A strut (i) connects the first and second gondolas to a hull of the marine vessel (ii) including first and second boltable interfaces. Each of the boltable interfaces of the strut is configured to form a bolted joint interface with a corresponding one of boltable interfaces of the first and second gondolas.

A coaxial contra-rotating circumferential thruster includes: an input end, a one-way commutator, a two-way deflector, a steering support and two output ends. The input end is connected to a power device. The one-way commutator converts one rotation into two rotations having the same rotation speed and opposite rotation directions. The two-way deflector respectively indirectly connects two shafts of a contra-rotating sleeve shaft to two output shafts thereof by means of two bevel gear pair. Two unidirectional deflecting torques respectively generated by the two bevel gear pairs have the same magnitude and opposite directions. By transferring by means of a bracket or an output sleeve shaft, the two unidirectional deflecting torques cancel each other. The two output ends are respectively connected to two propellers (or rotors). A turnaround control device controls the steering support to be turned around, the control torque required for co-rotating and contra-rotating is the same.

A boat shaft seal system including a flexing gland configured to receive a boat drive shaft therethrough, the flexing gland having a first end configured to receive a shaft log fitting, and a second end configured such that the boat drive shaft extends therefrom, and a plurality of circumferential ribs formed along at least a portion of a length of the flexing gland and configured to allow limited flexing of the flexing gland.

A drive for a boat includes a housing that is arranged underwater during operation, and that houses an electric motor that drives a propeller. The housing includes a cooling section that includes a coolant duct.

A lower unit for a marine propulsion device includes a gearcase housing defined along a longitudinal center axis between a fore end and an aft end. A propulsor shaft extends through the gearcase housing along the longitudinal axis. A driveshaft extends non-parallel to the propulsor shaft and rotates in a direction of rotation when powered by an engine. The driveshaft is coupled in torque-transmitting relationship with the propulsor shaft. A skeg projects from a bottom surface of the gearcase housing proximate at least the aft end thereof. The skeg or the gearcase housing is cambered such that a moment acting in a direction opposite the driveshaft's direction of rotation is induced on the skeg or the gearcase housing as the lower unit moves through water. A marine propulsion device is also disclosed.

A drive for a boat includes a housing that is arranged underwater during operation, and that houses an electric motor that drives a propeller. The housing includes a cooling section that includes a coolant duct.

A boat shaft seal system including a flexing gland configured to receive a boat drive shaft therethrough, the flexing gland having a first end configured to receive a shaft log fitting, and a second end configured such that the boat drive shaft extends therefrom, and a plurality of circumferential ribs formed along at least a portion of a length of the flexing gland and configured to allow limited flexing of the flexing gland.

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.