Does my MRU need recalibration?
The Norwegian Subsea MRU calibration certificate is valid for 4 years, and full product specification is maintained in this period under normal operating conditions.
Notes:
- We do not normally advise re-calibration of the MRU during its lifetime.
- The specified heave accuracy of 5 cm / 5% is maintained over the MRU's lifetime, also without re-calibration.
- The specified accuracy in roll & pitch for a given model is usually met over the MRU's lifetime under normal operating conditions as Norwegian Subsea uses only validated sensors with exceptional stability.
- Re-calibration and validation of the MRU every 4th year is recommended only if the customer requires full product specification after expiration of a valid calibration certificate.
- The lifetime accuracy in roll & pitch, without re-calibration and under normal operating conditions, not exceed
- 0.1 degrees for the 3000 model
- 0.05 degrees for the 6000 model
- 0.02 degrees for the 9000 model
- Thus, selecting a more accurate model than initially required may extend the calibration intervals or remove the need for re-calibration.
- The computed MTBF (mean time between failure) for a NORSUB MRU Marine is 100 000 hours, but actual lifetime depends on use, vibrations, and temperature. An MRU lifetime of 10 years or more under normal continuous operation can be expected.
In summary, for most applications, no recalibration is required. Examples:
- The MRU 3000 for Helideck monitoring applications. The requirement is 0.1 degrees roll/pitch accuracy and the MRU 3000 will always stay within this accuracy requirement without recalibration.
- The MRU 3000 Marine for DP systems roll/pitch sensor. The MRU 3000 will always stay within the accuracy requirement without recalibration.
Re-calibration and validation of the MRU is done in the factory in Oslo, Norway. Normal turn-around time is one week. Re-calibration includes a complete validation of the MRU, ensuring that the MRU is in full working order.
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
Hazardous areas
Connectors
Pigtail cable
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%
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
- Read the full answer
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.
- Read the full answer
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
- Read the full answer
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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