Active Heave Compensation: How It Works, Why It Matters, and How to Implement It
Not sure if your winch is suitable for AHC?
What is Active Heave Compensation?
Active heave compensation (AHC) is a control technology that measures vessel motion in real time and uses that data to drive a winch or cylinder in the opposing direction, keeping subsea loads stable regardless of wave conditions. The result is a longer operational weather window, reduced equipment wear, and safer offshore operations.
This guide covers how AHC works, how it compares to passive systems, which operations benefit most, and what to look for in an AHC controller.
Active Heave Compensation VS Passive Heave Compensation
Passive heave compensation (PHC) is a technique used to reduce the effects of vessel motion by using the natural damping characteristics of the system to reduce the amplitude of the heave motion. This is typically achieved through the use of hydraulic cylinders or tension control on winches. Passive heave compensation systems are simple and reliable, but they are not as effective at reducing heave as active heave compensation systems.
In contrast, active heave compensation measures the vessel motion using a motion reference unit (MRU) and uses this information to control a winch or a cylinder. Active heave compensation systems used to be more complex and require more maintenance than passive systems, until the new AHC Controller entered the market.
The practical difference: a passive system reduces motion amplitude by 40-60% through mechanical damping. An active system using a dedicated controller and MRU typically achieves 90-98% motion reduction, making operations viable in sea states where passive systems fall short.
Advantages of Active Heave Compensation
The primary benefit of Active Heave Compensation (AHC) is the ability to reduce the effects of vessel motion on equipment used for subsea operations. By actively compensating for the vessel motion, caused by waves, winds, and other external factors, equipment for underwater operations can remain stable and safe in rough seas. This is particularly important for vessels with subsea equipment that need to maintain a certain level of stability in order to safely operate in rough conditions.
In addition to providing stability, Active Heave Compensation (AHC) systems can also improve the efficiency of subsea operations. By reducing the effects of vessel motion, operations can be conducted more quickly, precisely, and safely. This can be especially beneficial for tasks that require precise movements, such as laying pipe and drilling operations.
Examples of applications that benefit from AHC:
ROV Operations
Extend the weather window for your ROV operations with an AHC system that stabilises the TMS and enables safe docking even in bad weather. Scantrol AHC can be retrofitted to a wide range of existing LARS systems. Learn more
Offshore Cranes
It is widely accepted that AHC provides an increase in performance for large offshore cranes. Scantrol AHC technology makes it affordable to utilize this advantage even on smaller cranes. Learn more
Intervention
Scantrol AHC combines winch and cylinder control to ensure safe and effective intervention operations.
Boulder Clearance
Scantrol AHC combines winch and cylinder control to ensure safe and effective intervention operations. Learn more
Drilling
Scantrol AHC will add accuracy to your passive compensation system and secure optimum bit weight and displacement control when drilling in varying structures. Learn more
Collecting Scientific Data
Most data sampling equipment is affected by vessel motion. Read more about how our AHC solutions can improve performance in all weather conditions. Learn more
Towing Operations
Whether you are towing a sonar or other survey equipment, Scantrol AHC will keep it stable at a certain depth or follow the seabed profile. Learn more
This brochure brings together documented mTrack AHC use cases from real offshore operations.
It shows how operators reduce the impact of vessel motion, work safely in rough seas, and complete time-critical missions when conditions would normally stop operations.
mTrack AHC Case Studies
How 300+ Vessels Work in Conditions That Used to Stop Operations
How Active Heave Compensation Works
The Active Heave Compensation (AHC) system works by sensing the heave motion and then applying an opposing motion. This process is known as active heave compensation. When vessel motion is detected, the sensors send a signal to the controller. The AHC controller then calculates the necessary control signal for the winch/cylinder. The AHC system continuously monitors the heave motion and adjusts the control signals applied to compensate for the changing motion. This allows the vessel to maintain a stable underwater operation, even in rough seas.
What to Look for in an AHC System
Not all AHC systems require months of engineering work or expensive sea trials. The key specifications to evaluate are:
- Integrated MRU: eliminates the need for a separate motion reference unit and external calibration
- Pre-configured apps: ready-made setups for winches, cranes, LARS, and cylinders reduce commissioning time
- Autotune capability: lets you test and tune at dockside rather than offshore
- Profinet and Modbus support: ensures compatibility with standard PLC environments without custom programming
- Retrofit compatibility: allows integration with existing winches, avoiding full system replacement
The mTrack AHC Controller is designed around all five criteria. It ships pre-calibrated, includes Dynatest simulation tools, and has been installed on 220+ systems globally across ROV operations, offshore cranes, LARS, and research vessels.
Vessel Operator / End User:
→ Download mTrack AHC Case Studies Brochure
The Components of an Active Heave Compensation System
mTrack AHC Controller with integrated motion reference unit is a key component for a safe and efficient active heave compensation system and Includes all the tools you need for easy installation and commissioning. Click here to read more about mTrack AHC Controller
Add Value to your New Winch with Scantrol AHC
An easy and fast way to add Active Heave Compensation (AHC) to your winch is to connect the mTrack AHC controller to your own winch control system, but if you need a complete winch control system, Scantrol can supply that as well.
We have specialists and design tools that can provide free assistance for the design of cost-effective hydraulic or electric AHC drives:
• Guiding on AHC requirements for specific applications.
• Guiding on the selection of hydraulic or electric drive systems and components.
• AHC Analyzer for calculation of AHC performance and required power, speed, and torque.
mTrack AHC Controller - probably the world’s most affordable and easy to integrate AHC Solution
• Off-the-shelf AHC controller with integrated MRU.
• A game-changer that makes AHC affordable even for smaller winches and cranes used for subsea operations.
• Includes all the tools you need for easy installation and commissioning, no need for expensive experts.
Frequently Asked Questions
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Passive heave compensation reduces vessel motion by 40-60% through mechanical damping using hydraulic cylinders or spring systems. Active heave compensation uses a motion reference unit (MRU) to measure vessel movement in real time and drives a winch or cylinder in the opposing direction, achieving 90-98% motion reduction. AHC extends the operational weather window significantly beyond what passive systems can deliver.
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A complete AHC system requires a motion reference unit (MRU) to measure vessel heave, a controller to process the MRU signal and calculate the compensation response, and a winch or hydraulic cylinder to execute that response. The mTrack AHC Controller integrates the MRU directly into the unit, eliminating the need for a separate sensor and external calibration.
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Not with mTrack. The Dynatest simulation tool allows you to test and tune the system at dockside before deployment. This reduces commissioning time and eliminates the cost of dedicated sea trials.
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Yes. Many standard winches are suitable for AHC operation. mTrack connects to your existing winch control system without custom PLC programming. Scantrol offers a free AHC analysis to determine whether your winch is suitable for retrofit.
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ROV launch and recovery, offshore crane operations, subsea intervention, LARS systems, scientific data collection, drilling and coring, and towing of sonar or survey equipment. AHC is particularly critical in operations where load stability directly affects safety, data quality, or equipment integrity.
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AHC controller cost varies by application and system complexity. mTrack is positioned as the most affordable off-the-shelf AHC controller on the market, designed to make AHC viable even for smaller winches and cranes where traditional systems were cost-prohibitive. Contact Scantrol for a quote based on your specific application.
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