Active Heave Compensation: Frequently Asked Questions (FAQ)
AHC Terminology
1. What is an AHC Crane?
An AHC crane is an offshore crane equipped with active heave compensation technology, using real-time control to keep the load stable by counteracting vessel motion. mTrack with an integrated Motion Reference Unit (MRU) makes this technology practical to add to smaller offshore cranes for subsea lifting and intervention work.
2. What is heave in Drilling?
Heave is the vertical motion of a vessel caused by waves, which disrupts drilling operations by affecting bit weight and displacement. Active heave compensation maintains precision during drilling by counteracting this motion, particularly in varying sea conditions.
3. What is Heave Compensator?
A heave compensator is a device that counteracts the effects of vessel movement caused by waves. These systems dynamically stabilize equipment, enabling safer and more efficient offshore activities such as lifting, drilling, or subsea construction.
4. What does heave do in offshore engineering?
Heave affects the stability of vessels and equipment, causing operational inefficiencies and safety risks during tasks such as ROV operations, crane lifts, and subsea construction. Heave compensation systems, particularly active heave compensation, reduce these motion disruptions and maintain operational stability.
→ Learn more about Active Heave Compensation for ROV Operations.
5. How is Heave Calculated?
Heave is calculated using motion reference units (MRU’s) that measure vessel displacement and velocity. This data is processed by an AHC controller, which controls winches or cylinders to counteract motion in real time.
→ Learn more about mTrack AHC Controller with Integrated MRU
6. What is the differences between heave and hoist?
Heave is the up-and-down motion of a vessel caused by waves. Hoist refers to raising or lowering a load using equipment such as a crane or winch. An active heave compensation controller synchronises the two, keeping the hoisted load steady regardless of vessel movement.
→ Learn more about mTrack AHC Controller with Integrated MRU
7. What is the difference between settlement and heave?
Settlement is the downward movement of ground or structures over time due to natural forces. Heave, in offshore contexts, refers to upward or wave-induced vertical motion of vessels. While they occur in different settings, both impact structural stability.
AHC Compared to Other Systems
8. How does the complexity and cost of AHC compare to PHC?
Active heave compensation was traditionally more complex and expensive to implement than passive heave compensation. Controllers such as mTrack have reduced this gap by making AHC systems easier to configure, test, and tune independently, lowering both complexity and cost while maintaining higher compensation performance.
9. What is the difference between constant tension and active heave compensation?
Constant tension maintains a steady pulling force on a line to prevent slack or over-tension, and its effectiveness depends heavily on the size and shape of the load. Active heave compensation instead measures vessel motion directly and adjusts the load's position to counteract it, giving higher precision independent of load size or shape.
AHC Compared to Other Systems
10. Why choose Scantrol for heave compensation?
Scantrol's mTrack AHC Controller is designed to be managed without hiring outside specialists, using pre-defined applications and an integrated motion reference unit (MRU) to simplify setup. Scantrol has been an independent supplier of active heave compensation systems since 1988.
Have questions or would you like to discuss your project?
If you have any questions about AHC, your application, or next steps, you are welcome to reach out directly.
Suzy Zhu
International Sales Manager
Email: suzy@scantrol.com
Phone: +47 465 20 370
Jan Kjærstad
CEO
Email: jan.kjarstad@scantrol.com
Phone: +47 911 59 434
We are happy to review your setup, answer technical questions, or schedule a meeting
Henry Boddington,
International Sales Manager
Email: henry@scantrol.com
Phone: +47 901 57 044