Echo Sounding

The measurement of water depth using the travel time of a reflected sound pulse.

The pulse is transmitted towards the seabed and its echo is detected after travelling down and back. An echo sounder converts that elapsed time into a depth using an assumed speed of sound through the water.

An echo sounding is an observed measurement at a particular time and position. It should not be confused with a charted sounding, which has been reduced to chart datum and incorporated into a hydrographic survey and chart. Equipment offsets and measurement conditions must be considered when comparing the two.