What is the best MRU for dynamic positioning?
A Motion Reference Unit (MRU) or a Vertical Reference Unit (VRU) is an important component in Dynamic Positioning (DP) systems to providing reliable and precise roll and pitch measurements. Norwegian Subsea Motion Reference Units (MRUs) are engineered for high accuracy and reliability, making them excellent choices for Dynamic Positioning (DP) systems. Our MRUs utilize advanced sensor fusion algorithms and state-of-the-art MEMS technology to provide precise 6DoF motion data (Roll, Pitch, Heave, Yaw, Surge, Sway) crucial for motion compensation of GNSS antenna and other position reference systems.
The NORSUB MRU can be configured with industry-standard protocols, enabling easy interfacing with existing DP systems or serving as a replacement for other MRUs/VRUs. The MRU/VRU can be installed in any direction. The configuration software allows for convenient setup of the remote monitoring point, specifically the GNSS antenna location.
To accommodate various installation requirements, the NORSUB MRU can be supplied with either an industrial junction box or a pigtail cable for integration into existing systems. This ensures compatibility and ease of implementation in different vessel setups.
It is also frequently used as a cost-effective, high-performance drop-in replacement (retrofit) for older MRUs/VRUs on existing DP systems, often without the need for recalibration.
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%
Further reading
Advanced motion compensation for sonars introduced at Ocean Business 2025
MRUs for vessel performance optimisation in focus at Europort 2025
Research Project to Test Value of MRU Data for Vessel Performance and Carbon Reduction
Related questions
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What is the difference between the MRU Marine and MRU Marine SW?
- The MRU Marine has an IP-68 rating, uses a Lemo 16-pin connector and has indicator lights.
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When navigating the complexities of motion sensing and navigation systems, it is essential to understand the distinctions between devices and systems like Inertial Measurement Units (IMUs), Inclinometers, Roll & Pitch sensors, Vertical Reference Units (VRU), Attitude and Heading Reference Systems (AHRS), Motion Reference Units (MRUs), Gyrocompasses, and GNSS-Aided Inertial Navigation Systems (GNSS/INS). Each serves specific purposes and offers different levels of functionality, accuracy, and application scope.
Gyrocompass
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The MRU Compact uses a standard RJ45 ethernet cable where power is supplied through Passive PoE (Power over Ethernet). In most cases you cannot connect the MRU directly to a an ethernet switch with PoE, since most of these are Active PoE.
We normally supply your first MRU Compact with a start kit containing a POE RJ45 spliter socket. You will only need standard RJ45 cat5 ethernet cables to connect the MRU to the spliter socket and the spliter socket to your PC or ethernet switch.
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