What is an Echo Sounder, its principle, errors and corrective action?

• The E/S Transducer is fitted at the keel of the ship.
• It means that the depth will be measured below the keel.
• To obtain the depth of water, the draft of the ship will have to be added to the measured reading. This can be achieved by setting this control which is known as setting the Zero Line to the ships draught.
• It is safest to keep the switch to 0 setting because there have been instances when the watch keeper presumed that he was reading below the keel reading whereas the zero line was set to the draft of ship. The watch keeper thus over read the depth and ship ran aground.

Feet /  Fathom / Meter Selector Switch of echo sounder