Active Heave Compensation

Accurate measurement of vertical motion at the crane tip or winch is crucial for the operation of Active Heave Compensated (AHC) cranes and winches.

illustration of our MRU Marine showing roll, pitch, yaw, surge, sway and heave

Motion Reference Units for Active Heave Compensation Systems

The Marine MRU provides precise heave motion measurements at user-selected remote monitoring points, making it an ideal choice for Active heave Compensation (AHC) applications.

The Marine MRU stands out in AHC applications particularly due to its exceptional performance and reliability in irregular waves. While some other MRUs struggle to provide accurate heave measurements in such conditions, Norwegian Subsea MRUs are specifically designed to deliver the highest performance in real sea conditions. This ensures accurate and reliable heave motion data for effective AHC operations.

Integrating the Marine MRU with your Programmable Logic Controller (PLC) is seamless and convenient, thanks to the availability of industrial Ethernet communication protocols such as Modbus TCP and Ethernet/IP. This enables straightforward interfacing and facilitates smooth integration into your existing control systems.

Why accurate MRU data is critical for Active Heave Compensation

In Active Heave Compensation systems, the performance of the Motion Reference Unit directly affects compensation accuracy, load stability, and operational safety. In real offshore conditions, vessel motions are irregular, coupled, and often combined with significant horizontal accelerations, conditions where low-quality motion sensors can introduce instability, delayed compensation, and reduced operational performance.

Accurate heave measurements in real sea conditions

Many motion sensors perform well in laboratory sine-wave testing but struggle in irregular offshore sea states. Norwegian Subsea MRUs are validated in real coupled vessel motions and maintain stable heave measurements during complex wave conditions and horizontal accelerations

Proven technology with long offshore track record

Norwegian Subsea MRUs have been used in Active Heave Compensation and 3D motion compensated systems for more than 10 years, serving 20+ OEMs and system integrators worldwide. Our sensors are used in offshore cranes, winches, LARS, and gangway systems where stable and accurate motion measurements are critical for safe and precise offshore operations.

Easy Integration into existing AHC systems and retrofit friendly

The MRUs support a wide range of marine industry protocols including Modbus TCP, Ethernet/IP, Modbus RTU, TSS1, SMCC, custom NMEA, and binary protocols, simplifying integration into PLCs, crane control systems, and offshore winches.

picture of an active heave compensated offshore crane

picture of an offshore crane and LARS system

Remote Monitoring Points for AHC Systems

Norwegian Subsea MRUs can output heave position, velocity, and acceleration at remote monitoring points, enabling accurate motion compensation directly at the crane tip, winch, or lifting point. The remote monitoring point can be dynamically updated through configuration commands, allowing the compensation point to be adjusted during operation or system setup.

This improves compensation accuracy in offshore lifting operations while simplifying system integration and reducing the need for additional external calculations, coordinate transformations, and system complexity.

Explore our products

Motion Reference Units designed for Active Heave Compensation

Norwegian Subsea produces industry-leading Motion Reference Units (MRUs) for marine and subsea applications. Our MRUs are robust and affordable, and offer high-accuracy performance, along with a plug-and-play interface.

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picture of an AHC Crane and a Launch and Recovery System

What our customers say

"The motion compensation industry was overmature with too few players. Norwegian Subsea disrupted that business, bringing the sector several steps ahead."

Jonas Røstad, Chief Commercial Officer, Miros

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"Other MRUs often fail in extreme climates, such as freezing Arctic waters or the intense heat below a metal deck in the tropics and Middle east... Norwegian Subsea MRUs remain stable and functional across its environmental range."

Johnny Rabben, CEO, ShoreConnection

Related customers

Next week, the maritime world gathers in Rotterdam for Europort 2025, one of the largest international meeting points for shipbuilders, technology providers and operators. With a strong focus on innovation and sustainability, the exhibition is an important platform for discussing how the industry can meet future demands through smarter, greener solutions.

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A year in Motion Reference Units...

From bathymetric surveys to subsea inspections and wave radar systems, our Motion Reference Units (MRUs) have been put to work in a wide range of challenging environments during 2025. As the year draws to a close we take a quick look back at some of the highlights, applications, and collaborations that helped shape another strong year of progress for Norwegian Subsea.

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Active Heave Compensation

Active Heave Compensation

Motion Reference Units for Active Heave Compensation Systems

Why accurate MRU data is critical for Active Heave Compensation

Accurate heave measurements in real sea conditions

Proven technology with long offshore track record

Easy Integration into existing AHC systems and retrofit friendly

Remote Monitoring Points for AHC Systems

Motion Reference Units designed for Active Heave Compensation

What our customers say

Related customers

Related products

Usage area

Connectors

Roll & Pitch accuracy

Heave accuracy

Usage area

Connectors

Roll & Pitch accuracy

Heave accuracy

Related questions

What is the difference between the MRU Marine and MRU Marine SW?

What is a Gyrocompass?

What is the role of motion monitoring in offshore operations?

Further reading

Advanced motion compensation for sonars introduced at Ocean Business 2025

Motion Reference Units for vessel performance optimisation in focus at Europort 2025

A year in Motion Reference Units...

Contact us

Active Heave Compensation

Active Heave Compensation

Motion Reference Units for Active Heave Compensation Systems

Why accurate MRU data is critical for Active Heave Compensation

Accurate heave measurements in real sea conditions

Proven technology with long offshore track record

Easy Integration into existing AHC systems and retrofit friendly

Remote Monitoring Points for AHC Systems

Motion Reference Units designed for Active Heave Compensation

What our customers say

Contact us