Norwegian Subsea

Norwegian Subsea produces Motion Reference Units, or MRUs, for marine, subsea and wind energy applications. An MRU measures and records the movements of a vessel or object in all six degrees of freedom: roll, pitch, yaw, surge, sway and heave. The company describes its units as robust and affordable, with high-accuracy performance and a plug-and-play interface, and says over 1200 Norwegian Subsea Motion Reference Units are in operation world-wide on over 600 vessels, floating and subsea structures. The distinguishing claim concerns test conditions. The company argues that many suppliers present test data solely for simple regular motions observed in laboratory conditions, whereas vessels at sea experience irregular and coupled motions, and that while most sensors perform well in sine wave motion only a select few excel in irregular sea conditions. Its own sensor fusion algorithms are presented as the means of getting precision motion measurements from high-accuracy sensors in any sea state, and it publishes how it validates its MRUs in real sea conditions. Four hardware variants are offered. The MRU Compact is rated IP 65 with RJ45 or RJ50 connectors; the MRU Marine is rated to 50 m depth and IP 68 with Lemo, SubConn 8 or SubConn 16 connectors; the MRU Subsea is rated to 6000 m depth with a SubConn 8 connector; and the MRU Ex is built for hazardous areas with a pigtail cable. Each comes in three accuracy grades: a 3000 series at plus or minus 0.05 degrees roll and pitch, a 6000 series at 0.02 degrees and a 9000 series at 0.01 degrees, all with heave accuracy of 5 cm or 5.0 percent. Setup is handled by the MRU Configurator, supplied free of charge, which defines communication ports, protocols and mounting orientation and location, and also monitors outputs in real time, plots variables, checks on-board diagnostics and updates firmware. Units are described as calibration-free after a single installation calibration. Applications fall into three groups. Motion monitoring covers safe landing of helicopters, ship and cargo stability, and monitoring of ships, risers or wind turbines, feeding real-time data into safe operating limits, digital twin models or AI algorithms. Motion control uses active heave compensation to improve stability and positioning during crane operations, subsea installations and similar offshore tasks. Instrument compensation accounts for sensor misalignments, offsets and drift to sharpen navigation, research and structural monitoring data. Published case studies show the units embedded in other manufacturers' equipment: Radac uses them as standard in its WaveGuide wave radar systems, Light Structures applies them in structural health monitoring tied to ABS and DNV SMART notations, ShoreConnection builds them into helideck motion monitoring and weather data systems, Miros runs them continuously inside its products, and Ultrabeam Hydrographic integrates the MRU Marine into the rotating multibeam head of its Black Swan autonomous survey platform.