A method for aligning steering angles of marine propulsion devices. The method includes receiving a first steering request to steer the marine propulsion devices, where when the first steering request is received, steering for a first device is deactivated and steering for a second device is activated, and changing a steering angle of the second device according to the first steering request while leaving a steering angle of the first device unchanged. The method includes receiving a request to activate steering for the first device and receiving a second steering request, then changing the steering angles of both the first and second devices when the second steering request is received after receiving the request to activate steering, and changing the steering angle of the second device while leaving the steering angle for the first device unchanged when the second steering request is received before receiving the request to activate steering.

In a vessel steering system including three or more propulsion devices, unintentional turning of a vessel is prevented when the vessel moves in an oblique direction. When a tilt direction of a joystick is an oblique direction between a longitudinal direction and a lateral direction, a controller is configured or programmed to correct at least one steering angle of a left propulsion device, a right propulsion device, and a central propulsion device so that a resultant force of propulsive forces of the left propulsion device, the right propulsion device, and the central propulsion device acts in a direction passing through a center of gravity of the vessel.

In a vessel steering system including three or more propulsion devices, unintentional turning of a vessel is prevented when the vessel moves in an oblique direction. When a tilt direction of a joystick is an oblique direction between a longitudinal direction and a lateral direction, a controller is configured or programmed to correct at least one steering angle of a left propulsion device, a right propulsion device, and a central propulsion device so that a resultant force of propulsive forces of the left propulsion device, the right propulsion device, and the central propulsion device acts in a direction passing through a center of gravity of the vessel.

An outboard motor includes an attachment attached to a hull, and a support vertically rotatably connected to the attachment and horizontally rotatably supporting an outboard motor main unit. The support includes an upper support and a lower support. The outboard motor includes a left reinforcement that includes a left upper connector connected to the upper support and a left lower connector connected to the lower support, and a right reinforcement that includes a right upper connector connected to the upper support and a right lower connector connected to the lower support. The left upper connector is located leftward of a left side of the upper support. The right upper connector is located rightward of a right side of the upper support.

An outboard motor includes an attachment attached to a hull, and a support vertically rotatably connected to the attachment and horizontally rotatably supporting an outboard motor main unit. The support includes an upper support and a lower support. The outboard motor includes a left reinforcement that includes a left upper connector connected to the upper support and a left lower connector connected to the lower support, and a right reinforcement that includes a right upper connector connected to the upper support and a right lower connector connected to the lower support. The left upper connector is located leftward of a left side of the upper support. The right upper connector is located rightward of a right side of the upper support.

In a system for controlling a watercraft, when a first mode is selected, a controller determines a route on which a single or a plurality of specified spots including a destination are located, and controls a marine propulsion device such that the watercraft moves along the route with a bow thereof being kept oriented in a predetermined cardinal direction. When a second mode is selected, the controller controls the marine propulsion device such that the bow of the watercraft is kept oriented in the predetermined cardinal direction without determining the route. The controller obtains a position of the watercraft. In the first mode, the controller determines whether or not the watercraft has passed through the destination. When the watercraft has passed through the destination in the first mode, the controller performs a mode switching from the first mode to the second mode and controls the marine propulsion device in the second mode.

In a system for controlling a watercraft, when a first mode is selected, a controller determines a route on which a single or a plurality of specified spots including a destination are located, and controls a marine propulsion device such that the watercraft moves along the route with a bow thereof being kept oriented in a predetermined cardinal direction. When a second mode is selected, the controller controls the marine propulsion device such that the bow of the watercraft is kept oriented in the predetermined cardinal direction without determining the route. The controller obtains a position of the watercraft. In the first mode, the controller determines whether or not the watercraft has passed through the destination. When the watercraft has passed through the destination in the first mode, the controller performs a mode switching from the first mode to the second mode and controls the marine propulsion device in the second mode.

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 marine vessel maneuvering system includes an operator, propulsion device controllers each configured or programmed to control driving of a respective propulsion device based on an operation signal from the operator, a first communication bus to transmit the operation signal to some of the propulsion device controllers, a second communication bus to transmit the operation signal to a remainder of the propulsion device controllers excluding the some of the propulsion device controllers, and a gateway device to connect the first communication bus to the second communication bus such that the first communication bus and the second communication bus communicate with each other.

A controller for a watercraft controls first and second marine propulsion devices to start moving the watercraft by setting a first default angle, a second default angle, and a default thrust ratio as a first target rudder angle, a second target rudder angle, and a target thrust ratio respectively when a desired motion of the watercraft is straight sideways movement. The controller determines at least one of a first correcting angle, a second correcting angle, and a correcting thrust ratio to reduce an error between the straight sideways movement of the watercraft and an actual motion of the watercraft. The controller corrects the first target rudder angle, the second target rudder angle, and the target thrust ratio with the first correcting angle, the second correcting angle, and the correcting thrust ratio, respectively. The controller repeatedly detects the error and repeatedly updates the correcting angles and the correcting thrust ratio.