Applied Underwater Acoustics

10.4. Multibeam Echo Sounders

MBESs can be considered a further development of the SBES. The MBES operates a fan of single beams with small individual widths and with a small angle separating each beam. The best multibeam systems today have 0.5–1 degree beam widths and simultaneously operate more than 800 beams. This makes it possible in hydrography to cover a broad swath along the ship's path with a theoretical maximum swath width of about 7.5 times the water depth with a 150 degree total fan angle. In deep water the swath width decreases from this maximum as a function of depth and seafloor type, for example, rock, sand, and mud. The swath width depends on the noise level and spectrum and the sea state and water column conditions. In deep water ...