Primary Active Heave Compensator


The latest development in active heave compensation systems is the primary active heave compensator, or PAHC. This involves regulating speed and direction of the winch by varying the swivel angle of the pump and thus regulating the volume flow rate. To change rotation direction of the winch the hydraulic pump swivels over center and works as a motor. Hence, the primary active heave compensator is a closed loop hydraulic system. A digital controller type HNC 100 is used to control the swivel angle of the pump according to the signals from the MRU.


Another characteristic feature of PAHC is that this type of heave compensation – like the rotating/secondary variant – is suitable for recovering energy in different phases of compensation. Among other things the energy released by easing the load (when the ship moves upwards) can be stored in a hydraulic accumulator. This energy becomes available again when the ship comes down and the load must be taken up. This energy-efficient system is achievable by using a modular kit with safety components, a brake and the required accumulators.