Single beam echo sounders measure water depth along the vessel track using a single downward-pointing acoustic beam. Though geometrically simpler than multibeam systems, they remain sensitive to vessel motion, where uncompensated roll, pitch, and heave directly affect the accuracy and reliability of every depth sounding.
Although a single beam echo sounder uses only one downward-pointing beam, vessel motion still degrades its measurements in several ways. Roll and pitch tilt the beam away from vertical, widening its effective footprint on the seabed and introducing across-track positional uncertainty in the measured depth. Heave compensation is equally critical, as the vertical motion of the vessel is superimposed directly onto every sounding.
For port and harbour surveys, river surveys, and inland waterway bathymetry where single beam systems are commonly used, accurate motion compensation ensures that depth measurements meet navigation safety standards. For fishing vessels using single beam echo sounders to assess bottom type, structure, and fish presence, accurate motion data helps avoid false bottom detections and improves the reliability of the depth-dependent information used in operational decisions.
The MRU Marine 3000 series provides the roll, pitch, and heave accuracy that single beam systems need for reliable bathymetry. For survey work requiring higher precision, the MRU Marine 6000 series delivers enhanced accuracy in the same easy-to-integrate, maintenance-free package.
50 m depth, IP 68
5 cm or 5.0%
Lemo or SubConn 8 or SubConn 16
6000 m depth
5 cm or 5.0%
SubConn 8
Ultrabeam, a specialist in hydrographic survey and underwater inspection, relies heavily on precise motion compensation to ensure accuracy in their 3D mapping projects. By integrating Norwegian Subsea’s compact, calibration-free Motion Reference Units (MRUs), Ultrabeam has significantly improved its survey data accuracy, while enjoying simplified integration, and enhanced operational efficiency in diverse surveying environments, from bridges, to offshore installations.
Motion Reference Units (MRUs) are crucial in bathymetric survey technology, providing precise motion compensation data to ensure reliable and accurate seafloor mapping. For users like Captain Sid Hynes, a seasoned mariner exploring Newfoundland’s shipwreck-rich waters, the Norwegian Subsea MRU has redefined what is possible, delivering exceptional performance even in incredibly challenging conditions.
Norwegian Subsea’s Motion Reference Units (MRUs) are now available integrated with WASSP’s multibeam sonar systems, offering enhanced motion data accuracy and performance for offshore applications.
