Active / passive heave compensation

Active heave compensation
- Compensation used to maintain the load at a specific height in relation to a fixed point, from a crane that is moving with the swell of the sea.
- The compensation is operated with pumps, or using an accumulator for heavy loads, and can be connected with a hydraulic motor or a linear cylinder. A unit on board the ship, which shows the exact height of the ship, controls the system.
- Active compensation if often used in combination with passive compensation. The passive part counteracts the greatest forces, while the active part regulates small movements. This is done to avoid having to regulate too large amounts of oil.

Passive heave compensation:
- Usually ordinary damping used to ensure better lifting control.