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How Electronic Depth Sounders Work

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An electronic depth sounder is an invaluable aid in determining the depth of the water underneath any particular vessel or watercraft.  It may also help to measure the distance of water between the bottom of a boat and a submerged object further beneath, thus helping the craft to avoid a collision.  Many fishermen use electronic depth sounders in order to locate where the best schools of fish are and to gauge the size of potential catches.  Another use is in the examination of plant growth and assorted debris that may prove to be navigational hazards through any particular charted course of a boat.

-  How a depth sounder works:

Electronic depth sounders use a sonar (sound navigation and ranging) system that emits sound waves from a device at the bottom of a hull of a watercraft.  These sound waves travel through the water and bounce off solid objects, or the ocean bottom, then bounce back where they are picked up by a receiver device on the boat.  Depths are calculated by time based measurements that take in to account the traveling speed of sound waves and how long it takes for them to travel back to the boat in a deflected state.  The electronic depth sounder can calculate measurements of depth instantaneously and provide clear, accurate and potentially life-saving information to the crew of a boat. 

-  Components in a depth sounder:

A depth sounder is made up of two main parts, known as a transducer (measures depth) mounted underneath the boat, and an instrument panel that is located inside the craft.  Depth information may be given in feet, metres and in the older style measurement, fathoms.  GPS navigation systems are also a common feature in many electronic depth sounders and allow the position and location of a watercraft to be noted.  The depth information that the instrument panel displays is updated in quick time when the boat is moving across the surface of the water.  Depending on the quality of the depth sounder, information displays may be in flat, linear form or show up as a detailed 3D image.  The inclusion of an electronic depth sounder on any boat can be a valubale addition to ensure safety; most boating accidents do not happen out on the deep ocean, but rather occur close to shorelines where hidden obstacles and dangers can lie submerged.

-  Information sources used:,,,,, Fishfinders

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