multibeamSonar

Multibeam sonar is a sonar system that uses an array of transducers to emit multiple acoustic beams, allowing simultaneous sampling of the seabed across a wide swath. By projecting a fan of beams and recording their travel times and angles, the system calculates depth at many points along the swath, with corrections for sound speed, geometry, and vessel motion. This enables higher-resolution bathymetric data than single-beam systems.

Typical multibeam installations can be hull-mounted on ships, towed behind a platform, or mounted on autonomous underwater vehicles. Core components include the transducer array, a navigation and motion reference unit, a data processor, and algorithms to apply sound-velocity profiles and motion compensation. Effective surveys rely on correcting for heave, roll, pitch, and changes in the water column to produce accurate depth measurements.

Output products from multibeam sonar include gridded bathymetric maps or swath mosaics and backscatter imagery that can indicate seabed type. These data support hydrographic surveying, route planning for cables and pipelines, dredging operations, offshore engineering, and marine science. The high data density enables detailed seabed characterization and habitat mapping.

Advantages of multibeam sonar include high spatial resolution, efficient coverage of large areas, and applicability across shallow to moderately deep waters. Limitations involve sensitivity to vessel motion, substantial data processing and calibration requirements, and reduced accuracy in rough seas or highly complex seabed environments. Achieving optimal results depends on accurate motion data, a well-characterized sound velocity profile, and proper system calibration.

Since the late 20th century, multibeam sonar has evolved with advances in transducer arrays, motion sensing, and processing software, progressively increasing depth accuracy and survey speed.