The principle of an echosounder is based on the concept of sound waves and their reflection. The echosounder system sends out a sound signal or pulse from a transducer, which is located on the bottom of the ship’s hull. The sound wave travels through the water and bounces off the seafloor or any object beneath the ship, such as a wreck, rocks or coral.
The time taken for the sound wave to travel from the transducer to the object and back to the transducer is measured by the echosounder system. The time taken is then used to calculate the depth of the water or the distance to the object, by applying the equation “depth = speed of sound x time taken / 2”.
The speed of sound through water is around 1500 meters per second, so the echosounder system can calculate the distance traveled by the sound wave and thus the depth of the water below the ship or the distance to any object on the seafloor.
This information is displayed on the echosounder screen in the form of a depth reading, which is used by the navigator to ensure the vessel maintains a safe under-keel clearance to avoid grounding. The echosounder is an important navigational tool that helps ensure the safety of the vessel and its crew.