Where should I mount the MRU?
Your MRU can be mounted almost anywhere on your vessel and in any orientation, but there are some guidelines you can follow to ensure the absolute highest accuracy of measurements from your device:
- Position your MRU close to the point which you’d like to measure
- Avoid mounting your MRU on machinery or in other areas with high levels of vibration, as this can negatively impact accuracy
- Avoid placing your MRU high up in your vessel, as this will lead to large horizontal accelerations, which can have a small negative impact on accuracy.
While we do recommend you position your MRU as close to the point of measurement as possible, if this can’t be achieved (perhaps because this area isn’t easy to access), you can also configure a remote measurement point.
Remote measurement points allow you to take measurements from almost any point on your vessel, but there will be a degradation in heave accuracy due to the lever arm between MRU position and measurement point.
As an example, a distance of 30 m between MRU and measurement point will give an additional inaccuracy in Heave of 2.6 cm at a roll/pitch accuracy of 0.05 degrees (3000 series). By selecting the 6000 series instead (0.02 degrees roll/pitch accuracy), this additional heave inaccuracy will be reduced to 1.0 cm. So by selecting a more accurate MRU series, you can maintain accuracy for measurement points further away from the MRU position.
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
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
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What is the purpose of the MRU in classed vessels?
The MRU (Motion Reference Unit) monitors vessel motions to evaluate risks related to sloshing and structural fatigue in cargo containment systems. It supports a condition-based inspection regime under DNV’s Alternative Survey Programme (ASP).
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