Sonar operates by emitting acoustic pulses into the water column and measuring the time it takes for echoes to return from the seafloor or submerged objects. Hydrographers use these systems to determine depth, map seabed topography, and locate hazards. The technology ranges from simple singlebeam units that measure depth directly below the vessel to complex multibeam and side-scan arrays that map wide swaths of the bottom.
We're getting too much aeration under the hull, and the sonar keeps losing bottom track.
The frequency dictates the application: high frequencies give crisp resolution for shallow object detection, while low frequencies penetrate deeper water but yield lower resolution.
Related terms
MBES
Multibeam echo sounder: a sonar that measures a fan of depths across the track on every ping, covering a wide swath.
Side-scan sonar
A sonar that images the seabed to either side of its track, revealing objects and textures by their echoes and shadows.
Singlebeam echo sounder
An echo sounder that measures one depth directly beneath the vessel on each ping, using a single vertical beam.
Ping
One transmit-and-listen cycle of a sonar; as a verb, to run the sonar.
Transducer
The device that turns electrical pulses into sound in the water and converts returning echoes back into signals.