Motion Reference Unit

MRU H, the versatile heave compensator, represents the fifth generation MRU specially designed for heave compensation applications. As an ideal sensor for a range of marine applications requiring highly accurate heave measurements, this unit enhances the precision in environments with extreme horizontal accelerations.

Enhanced Applications and Output Variables

The MRU H is an essential instrument constructed for precise motion measurements in marine environments. With applications that stretch from offshore cranes to echo sounders, it is also valuable for ship motion monitoring, helideck motion monitoring, hydroacoustic positioning systems, and hull stress monitoring. Its output encompasses significant data such as roll, pitch, and heave alongside linear acceleration in 3-axes, enabling accurate heave position, velocity, and acceleration in adjustable frames with additional outputs like angular rate vectors.

Advanced Functionality and Algorithm Utilization

Embodying three accurate accelerometers and MEMS angular rate gyros, the MRU H achieves remarkable reliability with no rotational or mechanical wear-out components. A distinctive feature of its function is the PFreeHeave algorithm, which uses historical measurements to deliver a precise, phase-free heave signal. This is especially beneficial in conditions of long swell or for seabed mapping applications that can utilize slightly time-lagged heave signals.

Seamless Configuration and Data Integration

Accompanied by user-friendly Windows-based configuration software, the MRU H allows for meticulous calibration of monitoring points and alignment with the vessel's center of gravity. It offers multi-point heave measurement outputs and compatibility with various protocols for seamless data sharing across multiple users. This capability underscores its adaptability to diverse operational needs while ensuring widespread accessibility through established data communication standards.

Key features

  • 0.05° roll and pitch accuracy
  • High accuracy heave measurements even in dynamic environments
  • Outputs on RS-232, RS-422, and Ethernet
  • High output data rate (200 Hz)
  • Precise heave at long wave periods by use of PFreeHeave® algorithms
  • Lever arm compensation to two individually configurable monitoring points
  • Meets IHO special order requirements
  • Small size, light weight, and low power consumption
  • No limitation to mounting orientation
  • Each MRU delivered with Calibration Certificate
  • Selectable communication protocols in the Windows-based MRU configuration software
  • 2-year warranty

Technical specifications


Roll/pitch Static RMS:
Roll/pitch Dynamic 1-sigma:
Heave Real-time RMS:
5 cm/5 %
Heave Period Real-time:
25 s
Heave Delayed RMS:
1 cm/1 %
Heave Period Delayed:
50 s

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