Echo Sounder

An echo sounder on a boat or ship is an instrument that is used to ascertain how deep the water is under the vessel’s keel. It does this by transmitting pulses of sound which bounce - or echo - off the sea bed, similar to the way sonar works.

The difference between an echo sounder and sonar, however, is that echo sounders transmit their pulse vertically while sonar transmits its pulse horizontally. There are two types of echo sounder: the single beam echo-sounder and the multi beam echo-sounder.