Kongsberg MRU-M-SU1 MRU S

The Kongsberg MRU-M-SU1 (often referred to as the MRU S) is a high-precision Motion Reference Unit specifically engineered for marine applications that require real-time compensation for vessel movement.

While it belongs to the broader "MRU" family used in Dynamic Positioning (DP), it is most commonly integrated with fish-finding sonars, multibeam echosounders, and hydrographic survey equipment to stabilize the display and data during rough sea conditions.1

Technical Specifications

The MRU-M-SU1 (MRU S) utilizes solid-state MEMS (Micro-Electro-Mechanical Systems) technology, meaning it has no moving parts and requires no scheduled mechanical maintenance.2

Feature    Specification

Model    MRU-M-SU1 (Part of the MRU S series)

Roll & Pitch Accuracy    0.1° RMS (Dynamic)

Heave Accuracy    5 cm or 5% (whichever is highest)

Angular Orientation Range    $pm 45^circ$

Output Data Rate    Up to 200 Hz

Interfaces    Ethernet (TCP/IP, UDP), RS-232. and RS-422

Power Supply    10 to 36 VDC

Housing Material    Anodized Aluminum

Key Capabilities

Motion Compensation: It calculates real-time Roll, Pitch, and Heave.3 This data allows sonar systems to "cancel out" the movement of the boat, ensuring that a school of fish or a seabed feature stays in the same position on the screen even as the boat rocks.

Lever Arm Compensation: The unit can be configured with "lever arms," allowing it to calculate the exact motion at a remote point (like the sonar transducer head) even if the MRU is mounted elsewhere in the hull.

Solid-State Reliability: Because it uses MEMS sensors rather than traditional mechanical gyros, it is highly resistant to vibration and has a significantly higher MTBF (Mean Time Between Failures).4

Easy Integration: It supports common marine protocols, including NMEA 0183. and can be configured via Kongsberg's Windows-based "MRC" software.5

Common Use Cases

Fishery Sonars: Vital for high-end sonar systems where wave motion would otherwise cause "smearing" or jumping on the display.6

Hydrographic Surveying: Used with single-beam or multibeam echosounders to correct depth soundings for vessel heave.

Offshore Cranes: Providing heave data to active heave compensation (AHC) systems to keep loads steady during transfer.7

Maintenance & Service Tip

Recalibration: Kongsberg recommends factory recalibration for the MRU S series every 2 years to maintain its specified static accuracy. If your system is reporting a "Sensor Health" warning or if you notice a "drifting" horizon on your sonar, the unit likely needs a professional recalibration.