What is the role of motion monitoring in offshore operations?
Motion monitoring is a cornerstone of safety, operational efficiency, and asset protection in the offshore industry. Whether on vessels, platforms, or subsea equipment, precise, real-time measurement of movement across all six degrees of freedom (Roll, Pitch, Heave, Yaw, Surge, and Sway) is essential for effective decision-making in complex, dynamic marine environments.
Applications in Offshore Oil and Gas
In offshore oil and gas, Norwegian Subsea’s Motion Reference Units (MRUs) deliver critical data for a range of essential systems:
- Dynamic Positioning (DP): MRUs provide motion-compensated GNSS antenna inputs and other reference data for precise station-keeping.
- Helideck Monitoring Systems (HMS): Accurate real-time Roll, Pitch, and Heave data ensure helicopter safety during landings and take-offs, in compliance with CAP 437 standards.
- Active Heave Compensation (AHC): MRUs stabilise winches, cranes, and launch and recovery systems (LARS), supporting safe lifting operations in high sea states.
- Motion Compensated Gangways: MRUs enable real-time motion correction for personnel transfer systems between vessels and offshore installations.
- Wave Radars: MRUs provide accurate real-time heave data to compensate downward-looking radar measurements for precise sea state assessment.
- Wind Lidar Buoys: MRUs correct for platform movement, ensuring stable wind data collection in offshore wind measurement campaigns.
Subsea Operations and Structural Monitoring
Motion monitoring also plays a vital role in subsea operations and structural health monitoring:
- ROV and AUV Navigation: MRUs provide 6DoF motion data for accurate navigation and control of Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs) during tasks like inspections, installations, and surveys.
- Subsea Surveys: Precise Roll, Pitch, and Heave compensation improves sonar data quality, reducing the need for repeated passes or extensive post-processing.
- Riser and BOP Monitoring: MRUs are used to assess motion and integrity of critical subsea infrastructure including risers and Blowout Preventers (BOPs).
- Structural Health Monitoring: MRUs track motion on both fixed and floating offshore structures, including platforms and offshore wind turbines.
Norwegian Subsea MRU Solutions
Norwegian Subsea offers a comprehensive range of high-performance MRUs tailored for offshore environments:
- MRU Marine: IP68-rated for topside or shallow water applications.
- MRU Subsea: Housed in a compact, robust titanium casing, depth-rated to 6000 metres, ideal for deepwater and subsea operations.
- MRU Ex: Certified for hazardous environments, including areas with explosion risks.
All our MRUs are engineered with advanced MEMS technology and proprietary sensor fusion algorithms. They support standard industry communication protocols such as UDP, Modbus TCP, and Ethernet/IP, ensuring seamless integration with control systems. With no need for recalibration in most cases, they offer long-term reliability and cost efficiency, making them suitable for both new installations and retrofit projects.
Related products
Usage area
50 m depth, IP 68
Connectors
Lemo or SubConn 8 or SubConn 16
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
IP 65
Connectors
RJ45 or RJ50
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
6000 m depth
Connectors
SubConn 8
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
Hazardous areas
Connectors
Pigtail cable
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Further reading
MRUs for vessel performance optimisation in focus at Europort 2025
Research Project to Test Value of MRU Data for Vessel Performance and Carbon Reduction
Advanced motion compensation for sonars introduced at Ocean Business 2025
Related questions
- Read the full answer
The MRU Marine is IP-68 rated with Lemo connectors and LEDs. The Marine SW supports 50m depth, uses SubConn connectors, and comes in two versions differing by available output combinations.
- Read the full answer
A Vertical Reference Unit (VRU) is an advanced device that measures the attitude of an object, specifically its Roll and Pitch.
- Read the full answer
Norwegian Subsea’s Motion Reference Units (MRUs) are designed to deliver real-time data through a combination of high-end MEMS sensors, advanced sensor fusion algorithms, and onboard data processing systems.
Related applications
Wave Radar
Accurate heave measurements play a vital role in compensating for Wave Radar measurements when installed on ships or other floating vessels.
Wind Turbines
Accurate and precise motion monitoring is crucial for wind turbine towers to ensure structural integrity and optimise performance.
Helideck Monitoring
Accurate measurement of roll, pitch, and heave motions is crucial for assessing the safety of helidecks during helicopter landing and take-off operations.
Dynamic Positioning
Dynamic positioning (DP) of vessels necessitates roll and pitch compensation of the GNSS antenna to ensure accurate positioning of the ship's control point.
Floating Wind Base Motion Monitoring
Monitoring the movements and structural integrity of floating wind foundations, including both the base and turbine, along with the anchoring system, is crucial.
Subsea Surveys
Subsea surveys often demand precise tilt measurements (roll and pitch) for various purposes, such as installation tasks or continuous monitoring of tilt changes and deflections in subsea structures.
Motion Compensated Gangways
Accurate measurements of all 6 degrees of freedom are essential for the automatic motion control of gangways.
Offshore Fish Farms
Offshore fish farming presents unique challenges, requiring continuous remote monitoring of all onboard systems, including roll, pitch, and heave motions.
Riser Monitoring
The NORSUB Subsea MRU is specifically designed to provide highly accurate measurements of roll, pitch (inclination), and lateral motions in risers.
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.
Wind Lidar Buoys
Metocean buoys, lidar buoys, and other instrument/sensor carrying buoys, need reliable motion measurements to motion compensate pay load sensors, or to collect motion data for post processing.
BOP Monitoring
Accurate motion sensors play a crucial role in the structural monitoring of Blowout Preventers (BOPs), enabling the measurement of inclination and lateral displacements.
Hydrography New
Accurate measurements of roll, pitch, and heave are crucial for achieving optimal results when compensating multibeam echosounders for vessel motion.
Hydrography
Accurate measurements of roll, pitch, and heave are crucial for achieving optimal results when compensating multibeam echosounders for vessel motion.
ROV/AUV
Reliable motion sensors are vital components in the navigation system and motion compensation of payload sensors for ROVs and AUVs.
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