Echo Sounders

One of the great mysteries of boating is wondering what lies beneath us, between the water and the bottom. An echo sounder can help us in our exploration of the world below the depths.
 
  • An echo sounder sends sound wave pulses from a transducer that’s usually located on the bottom of a ship/boat’s hull. These pulses travel through the water, hit submerged objects (the ocean floor, wrecks, large schools of fish), bounce off these things, and return upwards to the transducer.
  • The echo sounder knows how fast the sound pulses were going when they left the boat, so when it calculates the time it takes for the pulses to return, the echo sounder can indicate the distance from the boat to ocean’s bottom (or to the wreck located on the bottom, etc).
  • Echo sounders used on big ships to assess the water’s depth are often called fathometers, because commercial vessels use fathoms, instead of feet, as their unit of water depth measurement.
 
The fishfinder on your boat uses the same general principles of operation as the original echo sounder/fathometer to show you hidden structures, submerged contours, and schools of fish.