Introduction

The echo sounder is an important and necessary electronic navigation instrument that determines the depth of water under the keel.
This instrument is one of the prime considerations for safe navigation.
An echo sounder consists of the transducer and the display.
The transducer transmits ultrasonic waves through the water.
The wave strikes the seabed and part of the wave are then reflected back and received by the transducer.
Knowing that the ultrasonic wave travels through water at a nearly constant speed of 1500 meters (4921 feet) per second at a temperature of 13°C at a salinity of 35
(35 parts per thousand), the depth can be determined by calculating the time difference between the transmission and the reception of the ultrasonic wave.
The determined depth information is converted into visual or graphic form.