A monitor and alarm system is provided for a marine vessel having a rotatable propeller drive shaft supported by one or more water-cooled bearings contained in strut barrels mounted on struts extending from the vessel hull or in stern tube assemblies. A heat sensor on the hull senses the ambient temperature of the water surrounding the vessel and one or more sensors on one or more bearings sense the temperature of the bearings. The sensed temperatures are electrically communicated via wires or wirelessly to gauges for monitoring and to a processing unit. The processing unit compares the sensed temperatures and generates a signal to an alarm device to initiate a bearing overheat warning or alarm if the differential between the bearing temperature and the ambient water temperature exceeds a predetermined amount.

A monitor and alarm system is provided for a marine vessel having a rotatable propeller drive shaft supported by one or more water-cooled bearings contained in strut barrels mounted on struts extending from the vessel hull or in stern tube assemblies. A heat sensor on the hull senses the ambient temperature of the water surrounding the vessel and one or more sensors on one or more bearings sense the temperature of the bearings. The sensed temperatures are electrically communicated via wires or wirelessly to gauges for monitoring and to a processing unit. The processing unit compares the sensed temperatures and generates a signal to an alarm device to initiate a bearing overheat warning or alarm if the differential between the bearing temperature and the ambient water temperature exceeds a predetermined amount.

A vessel propulsion apparatus includes a cylindrical duct including a stator and a propeller. The propeller includes a rim including a rotor disposed at a position facing the stator and defining an electric motor in combination with the stator, and blades on an inner side in a radial direction of the rim. A fluid bearing is provided on the duct and defines a gap into which surrounding water is introduced between the fluid bearing and the rim, and is water-lubricated with respect to the rim due to water introduced into the gap from the surroundings. The vessel propulsion apparatus further includes a motor controller that drives the electric motor by rotation speed control in a rotation speed control region in which an output command is not more than a predetermined value, and drives the electric motor by torque control in a torque control region in which an output command is more than the predetermined value.

A vessel propulsion apparatus includes a cylindrical duct including a stator and a propeller. The propeller includes a rim including a rotor disposed at a position facing the stator and defining an electric motor in combination with the stator, and blades on an inner side in a radial direction of the rim. A fluid bearing is provided on the duct and defines a gap into which surrounding water is introduced between the fluid bearing and the rim, and is water-lubricated with respect to the rim due to water introduced into the gap from the surroundings. The vessel propulsion apparatus further includes a motor controller that drives the electric motor by rotation speed control in a rotation speed control region in which an output command is not more than a predetermined value, and drives the electric motor by torque control in a torque control region in which an output command is more than the predetermined value.

A method and an arrangement for sealing a propeller shaft. The propeller shaft is rotatably supported with a bearing arrangement inside a pod that is suspended at a hull of the marine vessel. The bearing arrangement includes at least two seal rings axially spaced apart from each other such that at least one lubricant seal chamber is delimited. The arrangement includes a lubrication arrangement for conducting lubricant to and from said bearing arrangement. The lubrication arrangement includes an additional lubrication circulation line for conducting a part of said flow of lubricant to and from said at least one lubricant seal chamber. The lubrication arrangement being additionally configured to create a flow of lubricant in the additional lubricant circulation line and in said at least one lubricant seal chamber.

The invention relates to a thrust generating assembly for a marine vessel, comprising a rotatable device (201) adapted to carry a thrust generating device adapted to generate a thrust by acting on water supporting the marine vessel, wherein the thrust generating assembly comprises a bearing (211, 212) for the rotatable device (201), wherein the bearing (211, 212) comprises an envelope (222) adapted to be fixed to a part of the vessel which is stationary in relation to a rotational axis (R) of the rotational device, wherein the thrust generating assembly comprises a liner (221) which is fixed to the rotatable device (201), wherein the liner (221) is electrically isolated from the rotatable device (201).