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Secondary Active Heave Compensator


Fuel costs, green shipping and valuable deck space: Energy efficiency definitely is a major concern in the maritime and offshore industries. Secondary Rotary Active Heave Compensation Systems (RAHC) recover energy with every wave and reuse it. Ultimately, these systems use up to 65% less energy. Your advantage: a reduction in installed power, smaller footprint for the hydraulic power unit and tanks, less fuel costs and reduced exhaust emissions.

More than one hundred RAHC systems from Rexroth are in service in cranes and winches, positioning loads of up to 400 tonnes safely. Their principle is simple but genius: during the upward movement of the vessel the drive unwinds the winch cable that works like a pump. In the following downward movement the drive works like a motor, reusing the stored energy from the accumulator. RAHC systems respond dynamically, which is crucial in wave motion conditions that vary constantly.

Rotary Active Heave Compensation types

The latest generation rotating active heave compensators is based on secondary controlled drive technology and pre-eminently is suitable for the controlled handling of loads from 20 to 100 tons.

  RAHC 25 RAHC 50 RAHC 75 RAHC 100
SWL 25 mT 50 mT 75 mT 100 mT
Winch drive 800 kW 1600 kW 2400 kW 3200 kW
AHC power 200 kW 400 kW 600 kW 800 kW
Hoisting power 150 kW 300 kW 450 kW 600 kW


  • High dynamic of speed and torque
  • High accuracy and repeatability
  • Possibility of storage and recovery of energy
  • Parallel operation of several other consumers without restriction
  • Increased safety for load, equipment, personnel and environment
  • High-responsive performance
  • Versatile and flexible operation
  • Compact system, minimum claim to deck space
  • No additional operators required