A computer implemented diagnostics system for a marine propeller drive unit is provided. The diagnostics system comprising processing circuitry connected to a speed sensor system and to a control unit associated with the electric machine. The speed sensor system is arranged in connection to the differential arrangement to provide propeller speed data to the processing circuitry indicative of a speed of rotation of at least one of the propeller axles of the self-balancing propeller drive unit. The control unit is arranged to provide motor current data to the processing circuitry indicative of a motor current drawn by the electric machine. The processing circuitry is arranged to monitor the motor current data from the control unit, and the propeller speed data from the speed sensor system, and to classify a state of the self-balancing propeller drive unit into a pre-determined number of states comprising one or more fault states, based on the motor current data and on the propeller speed data. The processing circuitry is arranged to trigger an action by the diagnostics system in case the state of the self-balancing propeller drive unit is classified as a fault state.

The present invention relates to a device for optional activation of a vertical-axis propeller to be configured on the lower surface of a marine vessel, said device comprises a vertical-axis propeller; a sliding means associated with the lower surface of the marine vessel and sliding the vertical-axis propeller; at least one slider that is associated with the vertical-axis propeller and is in sliding relation with the sliding means; and at least one driving means for driving the vertical-axis propeller in upwards and downwards in the sliding direction.

Dual propeller assemblies for driving engagement by a propeller drive shaft may include at least two propellers having a forward propeller and a rear propeller rearwardly of the forward propeller. The forward propeller may include a forward propeller hub with a forward propeller hub wall having a forward propeller hub outer diameter. A forward propeller hub bore may be formed by the forward propeller hub wall and configured to receive the propeller drive shaft for driving engagement of the forward propeller hub thereby. The forward propeller hub bore may form a passageway for flow of exhaust gas configured to traverse the forward propeller between the propeller drive shaft and the forward propeller hub wall. The rear propeller may include a rear propeller hub with a rear propeller hub wall having a rear propeller hub outer diameter less than the forward propeller hub outer diameter of the forward propeller hub wall of the forward propeller hub. A rear propeller hub bore may be formed by the rear propeller hub wall. The rear propeller hub bore may be configured to receive the propeller drive shaft for driving engagement of the rear propeller hub thereby. The passageway for flow of exhaust gas may be configured to traverse the rear propeller hub wall exterior to the rear propeller hub bore of the rear propeller hub.

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.

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 are a propulsion device for a ship and a ship including the same. The propulsion device for the ship includes: a rear propeller fixed to a rotation shaft; a front propeller that is rotatably supported on the rotation shaft in the front of the rear propeller; at least one bearing interposed in at least one of spaces between a hub of the front propeller and the rotation shaft and between the rotation shaft and a ship body; and an inverse rotation unit that inverts rotation of the rotation shaft, transfers the inverted rotation to the front propeller and includes a gearbox that is accommodated in an installation space formed in a tail of the ship body in a state in which a plurality of gears for implementing inversion of the front propeller are embedded, wherein at least one measurement unit for measuring operating states of the at least one bearing is mounted to the rotation shaft.

A marine propeller combination for a marine propulsion unit includes a first propeller and a second propeller arranged to rotate simultaneously in opposite directions about a common rotational axis. The marine propeller combination is configured such that the first and second propellers are angularly positioned such that during one revolution one of the blades of the first propeller is aligned with a drive leg of the marine propulsion unit when a blade gap of the second propeller is aligned with the drive leg, or one of the blades of the first propeller is aligned with the drive leg when one of the blades of the second propeller is aligned with the drive leg. The disclosure further relates to a marine vessel and to a method of operating a marine propeller combination.

The outboard motor includes a lower unit that rotatably supports a propeller shaft installed with propellers, and a shift unit that switches a shift position. The lower unit is provided with an upwardly opened shift unit storage chamber and a lid member that covers the upper side of the shift unit storage chamber. The shift unit has a dog clutch that switches the shift position by reciprocating in parallel with the drive shaft, a shift fork member that reciprocates the dog clutch in parallel with the drive shaft, and an actuator that reciprocates the shift fork member in parallel with the drive shaft. The actuator is supported by the lid member.

Disclosed are a propulsion system for a ship, a method of assembling the same, and a method of disassembling the same. The propulsion system for the ship includes: a rear propeller fixed to a rotary shaft; a front propeller that is rotatably supported on the rotary shaft in front of the rear propeller; a contra-rotating device that is mounted in an installation space at a rear end of a hull so as to reverse the rotation of the rotary shaft and transmit the reversed rotation to the front propeller; a propeller connecting member that connects the contra-rotating device and the front propeller to transmit a rotational force; and a thrust supporting device that is provided between the contra-rotating device and the propeller connection member to support thrust of the front propeller.

A tapered counter rotating propeller hub assembly for a stern drive marine propulsion assembly. The propeller hub assembly having aligned forward and aft tapered hubs with a predetermined slope.