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Motion Reference Unit


MRU family
MRU product range.

Operating vessels at sea is, by its very nature, a highly challenging activity. In order to undertake tasks such as wave height monitoring, using cranes during rough weather, or determining where vessels are using dynamic positioning, roll, pitch, yaw and heave motion needs to be measured. This is where Motion Reference Units (MRUs) come in and KONGSBERG has been a leader in this field for over 20 years.

The ultimate marine motion sensor

The MRU is suitable for any maritime operation that requires attitude determination and motion compensation. Kongsberg's range of motion sensors provides high accuracy motion measurements in all dynamic environments. They cover all marine activities, from small hydrographic vessels to large vessels and installations.

Typical applications for MRUs

  • Motion compensation of single and multi-beam echo sounders
  • Orientation and attitude measurements on AUVs and ROVs
  • High speed craft motion control and damping systems
  • Heave compensation of offshore cranes
  • Dynamic positioning
  • Hydro acoustic positioning
  • Ship motion monitoring
  • Ocean wave measurements
  • Antenna motion compensation and stabilization

High reliability

Built with solid-state gyros and accelerometers, Kongsberg's MRUs provide realtime motion measurements with high dynamic accuracy. In-house, state-of-the-art design, construction and assembly provide an MRU with extremely high reliability in the most demanding marine environments.

Merging the art of technology with applications


Micro Electro Mechanical System (MEMS) -based gyros have been implemented in many different variations over the past 20 years and a constant focus on innovation and ingenuity has led to constant improvements in price/performance. Consequently, MEMS-based gyros today challenge the 'prone to wear' mechanical gyro solutions, as well as gyros based on fibre optic (FOG) technology. A gyro developed by Kongsberg, optimized for use in the high-end of the Kongsberg Motion Reference Unit (MRU) product range, is a defining example of the MEMSbased gyro design, demonstrating new performance levels for this technology.



The MRUs can be supplied with a variety of accessories such as; MRU mounting brackets, junction boxes, cables and subsea housings, depth rated from 10 to 4,000 metres.

State-of-the-art production facilities

To ensure the required quality and meet the demands from our customers, the production process is continuously improving. Service, calibration and verification of MRU units in order to meet required specifications are a vital part of the process.

Our production process meets all relevant standards and is certified in accordance to ISO 9001and ISO 14001.

MRU product range

PFree Heave*
PFree Period*
MRU 5+ 0.008° 0.001 m/s2 5 cm 2 cm 25 s 50 s
MRU 5 0.02° 0.01 m/s2 5 cm 2 cm 25 s 50 s
MRU E 0.05° 0.01 m/s2 5 cm 3 cm 25 s 50 s
MRU H 0.05° 0.01 m/s2 5 cm 3 cm 25 s 50 s
MRU 3 0.08° 0.02 m/s2 5 cm 4 cm 18 s 50 s
MRU 2 0.10° 0.01 m/s2        
MRU D 0.35° 0.04 m/s2        

*PFreeHeave® is a delayed heave output where phase errors are removed. The delay is 132 sec.

Services & Aftermarket Support

24/7 Technical Support

Our 24/7 technical support team is there to help at any time, day or night, wherever your vessel is. We will manage your call from the time it is received to the time the issue is resolved.

The team has direct access to the experts in our product centres, should additional support be required, and for the more complex issues a product specialist will be assigned to you. Our priority is to get the right expertise quickly matched with the issue to provide the answers you need.

Support information this product

Key support information for this product is found here:

Contact us

The following contact information will put you through to our global support team:


We understand the importance of having the right parts, available in the right place, at the right time.

We have streamlined our operations to reduce lead-times and increase spares availability.

Contact us

Our 24/7 technical support team is there to help at any time of day or night wherever your vessel is located. They manage your call from the time it is received to the time the issue is resolved.

Contacting any of these numbers will put you through to our global support team:

Our local representatives will respond to your support requirements 24/7. If you want to know more about how our enhanced service delivery will benefit you, please contact our nearest Office.

Product Training

Ensure that your crew is properly and thoroughly trained. This will reduce operational risk, downtime and maximise return on asset investment.

It also enables you to meet regulatory standards, improve crew safety and retain key personnel. In our state of the art training centres qualified and experienced trainers are able to provide your crew with practical training tailored to suit your products, systems and operational requirements. Our instructors can also train your crew on-board your vessel.

From hands on experience on live products in our training centres, to experiencing real life scenarios in our world class simulators all our courses are designed to focus on efficient and safe operation and maintenance of your Kongsberg Maritime equipment.


  • BRAZIL, Rio de Janeiro
  • CANADA, Halifax
  • CHINA, Shanghai
  • GREECE, Athens - Elliniko
  • MEXICO, Veracruz
  • NORWAY, Horten Bekkajordet
  • NORWAY, Horten Strandpromenaden
  • NORWAY, Kongsberg
  • NORWAY, Trondheim Grilstad
  • NORWAY, Trondheim Seatex
  • POLAND, Szczecin
  • SINGAPORE, Singapore, Jurong East
  • SINGAPORE, Singapore, Tuas
  • SOUTH KOREA, Busan
  • UNITED KINGDOM, Aberdeen
  • UNITED STATES, Houston
  • UNITED STATES, New Orleans

This type of solution is ideal for theoretical training, especially for larger groups. It goes through detailed systems overview including drawings and functionality.

This type of solution is ideal for practical training with focus on maintenance and troubleshooting on actual products. This type of training used together with classroom training can provide a holistic view of complete systems.