What are the specifications of Norwegian Subsea MRUs?
Norwegian Subsea offers a range of high-performance Motion Reference Units (MRUs) designed for diverse marine, subsea, and offshore applications. All our MRUs measure 6 Degrees of Freedom (6DoF): Roll, Pitch, Heave, Yaw, Surge, and Sway. They are available in three distinct accuracy tiers based on Roll & Pitch performance: Series 3000 (±0.05°), Series 6000 (±0.02°), and Series 9000 (±0.01°). Standard Heave accuracy across the MRU range is 5.0 cm or 5.0%. For applications requiring only orientation data, Inclinometer/VRU versions are available, offering the same high Roll & Pitch accuracy without Heave/Surge/Sway output. Our sensors are designed for easy integration with broad protocol support and user-friendly web-based configuration.
The MRU Compact is designed for indoor or control box installations, featuring an IP65-rated anodized aluminum enclosure. It is exceptionally compact (12.0 x 5.7 x 5.3 cm) and lightweight (0.55 kg). Connectivity is simplified via an RJ45 or RJ50 connector supporting Ethernet communication (UDP, Modbus TCP, Ethernet/IP) with passive Power over Ethernet (PoE, 9-36V DC). The operating temperature range is -40 to +85°C.
The MRU Marine is built for on-deck use (IP68) or shallow water deployment up to 50m (MRU Marine SW version). Housed in anodized aluminum (15.4 x 8.6 x 6.7 cm, 1.2 kg), it offers versatile connectivity through a 16-pin marine connector or SubConn options, providing Ethernet, RS-232, RS-485, and PPS ports. Supported protocols include UDP, Modbus TCP/RTU, and Ethernet/IP. It operates from -40 to +85°C and is often used for cost-effective retrofitting of older systems. An optional junction box provides analog outputs (+/-10V, 4-20mA).
For deep-water applications, the MRU Subsea features a robust Titanium housing rated for 6000m water depth. It utilizes an 8-pin SubConn wet-mateable connector providing Ethernet and serial (RS-232 or RS-485) communication (UDP, Modbus TCP, Ethernet/IP). Despite its depth rating, it remains compact (7.6 x 7.6 x 16.5 cm) and weighs 1.6 kg. The operating temperature range is -40 to +70°C.
The MRU Ex is specifically designed for hazardous areas, certified to II 2 G Ex d IIC Gb. It features a durable AISI 316L stainless steel enclosure (19 x 19 x 20.5 cm, 15 kg excluding cable) and connects via a pigtail cable available in custom lengths. It provides Ethernet and serial (RS-232 or RS-485) communication options supporting UDP, Modbus TCP/RTU, and Ethernet/IP protocols. The operating temperature range is -20 to +40°C.
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Related products
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
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
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
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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