Abstract: A passive heave compensator comprising: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head, a gas phase above the piston head, and at least one oil phase below the piston head separated by a boundary; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and at least one accumulator, the or each accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator, and the or each oil phase being in communication with an oil phase in the main hydraulic cylinder; characterized in that the main hydraulic cylinder further comprises a cylinder sleeve co-axial with the piston head to provide, in co-ordination with the piston head, the boundary between the gas phase and the at least one oil phase in the main hydraulic cylinder.

Abstract: A passive heave compensator having: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head to divide the main hydraulic cylinder between a gas phase above the piston head, and oil phase below the piston head; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and an accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator and being in communication with the oil phase in the main hydraulic cylinder; wherein an oil phase includes a magnetorheological substance, and that the passive heave compensator includes one or more electromagnetic controllers.

Abstract: A passive heave compensator comprising: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head, a gas phase above the piston head, and at least one oil phase below the piston head separated by a boundary; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and at least one accumulator, the or each accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator, and the or each oil phase being in communication with an oil phase in the main hydraulic cylinder; characterized in that the main hydraulic cylinder further comprises a cylinder sleeve co-axial with the piston head to provide, in co-ordination with the piston head, the boundary between the gas phase and the at least one oil phase in the main hydraulic cylinder.

Abstract: A passive heave compensator having: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head to divide the main hydraulic cylinder between a gas phase above the piston head, and oil phase below the piston head; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and an accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator and being in communication with the oil phase in the main hydraulic cylinder; wherein an oil phase includes a magnetorheological substance, and that the passive heave compensator includes one or more electromagnetic controllers.