Abstract: A damping system for a heave compensator for an off-shore oil rig includes a hydraulic cylinder having a piston and a housing. The hydraulic cylinder is configured for accepting a hydraulic fluid. There is a flow passage for restricting the flow of the hydraulic fluid during movement of the piston in the housing. The hydraulic fluid is a magnetic fluid and the damping system includes a magnetic fluid management system for controlling a magnetic field at the flow passage. A heave compensator including such a damping system, and a method for controlling the damping of a heave compensator are also disclosed, the method including subjecting a magnetic fluid to a magnetic field at a flow passage for restricting the flow of the magnetic fluid.

Abstract: An apparatus for recuperation of hydraulic energy from an actuator comprises a first hydraulic machine having a first drive and a second hydraulic machine having a second drive mechanically coupled to the first drive. The first hydraulic machine is in hydraulic communication with an actuator, and the second hydraulic machine (20) is in hydraulic communication with an accumulator.

Abstract: A heave compensating system for a marine vessel includes a hydraulic machine configured to be coupled to a load suspended from the vessel and to vary the distance between the load and the vessel in response to heaving motion of the vessel. The system further includes a second hydraulic machine in fluid communication with a hydraulic accumulator, both the first and second hydraulic machines are mechanically connected to one another and a shared electric motor, and a controller configured to control hydraulic movement of the first and second hydraulic machines and to control the supply of power to the electric motor.

Abstract: An apparatus for tensioning a marine riser comprising a support for a number of actuators, where the support is connected to a vessel's structure, and where each actuator is connected to the support and to a marine riser, and where elements of the riser tensioner apparatus are enclosed.

Abstract: A heave compensating system for a marine vessel includes a hydraulic machine configured to be coupled to a load suspended from the vessel and to vary the distance between the load and the vessel in response to heaving motion of the vessel. The system further includes a second hydraulic machine in fluid communication with a hydraulic accumulator, both the first and second hydraulic machines are mechanically connected to one another and a shared electric motor, and a controller configured to control hydraulic movement of the first and second hydraulic machines and to control the supply of power to the electric motor.

Abstract: An apparatus for recuperation of hydraulic energy from an actuator comprises a first hydraulic machine having a first drive and a second hydraulic machine having a second drive mechanically coupled to the first drive. The first hydraulic machine is in hydraulic communication with an actuator, and the second hydraulic machine (20) is in hydraulic communication with an accumulator.

Abstract: An apparatus for tensioning a marine riser comprising a support for a number of actuators, where the support is connected to a vessel's structure, and where each actuator is connected to the support and to a marine riser, and where elements of the riser tensioner apparatus are enclosed.