The basics of sonar

About sonars

Sonar is a device for finding objects underwater using sound waves. For the purpose of fishing, sonar is defined as a device that can search both horizontally and vertically while a fish finder can search only vertically underneath the own ship.

Sonars transmit ultrasonic waves into the water below and receive the returning echoes from the seabed. Anything that gets hit by these ultrasonic waves will give a returning echo that shows up on the sonar display. The device that emits the ultrasonic waves is called the transducer.

To locate fish schools, Sonar shows a radar-like image of the surroundings of the ship. This image stretches from left to right and back and forth, showing the distribution and density of fish schools if present.

Purse seiners and trawlers worldwide rely on Sonar on a daily basis to get their catch.