The disclosure provides a pod propulsion system including first and second counter rotating propellers for providing thrust to propel a marine vessel. The pod propulsion system includes a first electric motor (i) for rotating the first propeller and (ii) electrically coupled to a first drive, the first drive being configured to control the first motor and a second electric motor (i) for rotating the second propeller and (ii) electrically coupled to a second drive, the second drive being configured to control the second motor. The first and second drives respectively control the first and second motors interdependently.

A marine plant assembly comprising a floating vessel and a plant operating unit attached to a buoyancy vessel in such a way that the operating unit is at least partially submerged during operation. At least one link element provides a hinged connection between the operating unit and the buoyancy vessel, thereby to allow movement of the operating unit from its submerged operating position to above the water level and adjacent the buoyancy vessel by said link element rotating into a position substantially parallel to the buoyancy vessel.

A marine plant assembly comprising a floating vessel and a plant operating unit attached to a buoyancy vessel in such a way that the operating unit is at least partially submerged during operation. At least one link element provides a hinged connection between the operating unit and the buoyancy vessel, thereby to allow movement of the operating unit from its submerged operating position to above the water level and adjacent the buoyancy vessel by said link element rotating into a position substantially parallel to the buoyancy vessel.

A propulsion unit includes a housing supported on a vessel. A propeller shaft extends in the housing. The propeller shaft is rotatably supported with a first bearing and a second bearing. A propeller is attached to at least one end of the propeller shaft. The first bearing includes a first radial bearing and a first thrust bearing. The first radial bearing is a sliding bearing positioned axially inside the first thrust bearing. The first bearing is positioned at the first end of the housing and the second bearing being positioned at the second end of the housing or vice a versa.

A propulsion unit includes a housing supported on a vessel. A propeller shaft extends in the housing. The propeller shaft is rotatably supported with a first bearing and a second bearing. A propeller is attached to at least one end of the propeller shaft. The first bearing includes a first radial bearing and a first thrust bearing. The first radial bearing is a sliding bearing positioned axially inside the first thrust bearing. The first bearing is positioned at the first end of the housing and the second bearing being positioned at the second end of the housing or vice a versa.

A method and an arrangement for sealing a propeller shaft located under water. The propeller shaft is arranged at a pod of a ship and an air chamber is provided circumferentially around the propeller shaft. The method includes supplying compressed air from a compressed air source to the air chamber, discharging compressed air from the air chamber in an air return line and colleting liquid present in the compressed air discharged from the air chamber in an intermediate leakage tank that is provided in the air return line. The method includes closing the air return line upstream of the intermediate leakage tank, and supplying compressed air to the intermediate leakage tank to effect flowing of liquid present in the intermediate leakage tank to a leakage tank.

A calibration method for at least one propulsion unit of a marine vessel, the at least one propulsion unit being arranged to provide a propulsive force to the vessel, the at least one propulsion unit being adjustable so as to change a respective steering angle of the at least one propulsion unit in relation to a hull of the vessel. The method includes controlling the at least one propulsion unit so as to provide at least one acceleration sequence, wherein the vessel is accelerated stepwise or continuously in each acceleration sequence, adjusting, continuously or repeatedly, during the acceleration sequence, the steering angle of the at least one propulsion unit, to keep the path of the vessel straight during the acceleration sequence, registering, during the acceleration sequence, a plurality of values of the respective steering angle of the at least one propulsion unit, and determining, based at least partly on the registered steering angle values, a respective reference steering angle of the at least one propulsion unit, which reference steering angle minimizes a deviation of an actual course over ground of the vessel from a desired course over ground of the vessel.

A calibration method for at least one propulsion unit of a marine vessel, the at least one propulsion unit being arranged to provide a propulsive force to the vessel, the at least one propulsion unit being adjustable so as to change a respective steering angle of the at least one propulsion unit in relation to a hull of the vessel. The method includes controlling the at least one propulsion unit so as to provide at least one acceleration sequence, wherein the vessel is accelerated stepwise or continuously in each acceleration sequence, adjusting, continuously or repeatedly, during the acceleration sequence, the steering angle of the at least one propulsion unit, to keep the path of the vessel straight during the acceleration sequence, registering, during the acceleration sequence, a plurality of values of the respective steering angle of the at least one propulsion unit, and determining, based at least partly on the registered steering angle values, a respective reference steering angle of the at least one propulsion unit, which reference steering angle minimizes a deviation of an actual course over ground of the vessel from a desired course over ground of the vessel.

A method is disclosed for controlling heading of a marine vessel having a steerable component coupled thereto, the steerable component being rotatable to affect a direction of movement of the vessel. The method is carried out by a control module and includes accepting a command to initiate a control mode in which the vessel's heading is to be maintained at a desired heading. The method includes receiving a current heading of the vessel and determining a heading error between the current heading and the desired heading. The method also includes determining if the vessel is on-plane or off-plane. In response to the vessel being off-plane, the method includes controlling the steerable component to rotate by at least a predetermined correction amount away from a starting position in a direction that will cause the vessel to rotate to reduce the heading error, and subsequently to rotate back toward the starting position.

A paddle assistance and propulsion system for use with personal watercraft is disclosed. The paddle assistance and propulsion system may include different mounting techniques that allow a propulsion device (e.g., a motor) to be coupled to various types of personal watercraft. Some mounting techniques may include the use of magnets to couple a motor-side mount to a boat-side mount. The paddle assistance and propulsion system may also utilize a variety of sensors in combination with control systems to provide various types of paddle assistance and different types of paddle assistance modes for the user of the personal watercraft.