Frequently Asked Questions

Below we have listed frequently asked questions and answers.
Feel free to contact us if your question isn’t answered here!

What is Heave Compensation?

Heave compensation is a technology used in offshore and marine applications to mitigate the effects of vertical motion, known as heave, experienced by floating structures such as ships, floating platforms, or vessels. Heave refers to the upward and downward movement of a structure caused by waves, currents, or other environmental factors.

What is a Passive Heave Compensator (PHC)?

A passive heave compensator (PHC) is a spring-damper system based on gas pressure and hydraulic fluid. As it is self contained, no external connections of hoses or wires are required.

What is an Active Heave Compensator (AHC)?

An active heave compensator (AHC) use sensors to detect the movement of the platform and then employ actuators (hydraulic or electric) to actively adjust the position of components, such as cranes or tools, to maintain stability and reduce heave-induced motions.

What is the difference between Active Heave Compensation (AHC) and Passive Heave Compensation (PHC)?

Both Active Heave Compensation (AHC) and Passive Heave Compensation (PHC) are techniques used on lifting equipment to reduce the influence of waves upon offshore operations. AHC differs from PHC by having a control system that actively compensates for any movement using external energy. Passive systems reacts to external forces without additional energy to control the motion.

Will a Passive Heave Compensator (PHC) reduce motion in air?

No, as passive heave compensators rely on external forces to reduce motion, they will have no impact on the movements of free hanging objects in air.

Will a Cranemaster Shock Absorber have any effect on peak loads for lifts in air?

Yes, utilization of a Cranemaster shock absorber will have an effect on peak loads for lifts in air. When there is relative motion between a lifted object and the boom tip, a snap load will occur. As a consequence, the dynamic amplification factor (DAF) will increase and potentially lead to unacceptable high peak loads. A Cranemaster unit will work as a shock absorber, efficiently removing these snap loads, and as a result reduce DAF and improve safety. Typically, this will enable you to conduct such lifts in higher sea states, and thereby increasing the operational weather window.

Read more: Shock absorption for pile run protection

Can a Passive Heave Compensator (PHC) be used to reduce dynamic hook loads when lifting through the splash zone?

Yes, a Cranemaster Passive Heave Compensator (PHC) is designed to instantly respond to its surroundings, take up slack wire and reduce dynamic loads.

Read more: Splash Zone Crossing

Can passive heave compensators be used together with active heave compensated systems?

Yes, Cranemaster PHC units will work perfectly together with an active heave compensator (AHC) that responds to inputs from an accelerometer.

Read more: Active Heave Compensation

What is the deepest operating depth for a Cranemaster passive heave compensator?

Cranemaster units are certified for operations down to 3000 meter. As of today units has been used at close to 3000 meter water depth.

What is the minimum and maximum load range for a Cranemaster unit?

The is no minimum load range, but a heave compensator is usually not needed for lifting operations with a load under 1t. Unit load range can typically be divided into ranges of 0-100t100-400t400-1200t and 1200t and above. For lifts over 1200t units may be used in parallel og custom build for a specific operation.