Sweep Width

Sweep width is the cross-track distance ensonified by a swath sonar in a single pass, the width of the seabed strip covered per survey line. For a multibeam echosounder it scales with water depth and the total angular swath: a system with a 120-degree swath covers roughly 3.5 times the water depth, so coverage shrinks in shallow water and widens with depth. Sweep width sets the line spacing needed for the overlap and full-bottom coverage that IHO S-44 orders demand; lines are run closer than the nominal swath so adjacent strips overlap and outer-beam quality stays inside the order limits.