What is a Fishfinder and why do I need one?

A fish-finder is an echo sounder (sonar) specifically designed to detect the presence of fish in the underwater environs of the host boat, in addition to measuring the overall depth of the water. A fish-finder uses echo-location to reflect electronic pulses off fish and other underwater features and converts this information into a graphic rendition, nowadays a full-colour high-definition screen or liquid crystal display unit. The image on the screen, which represents individual fish with a small icon or as a series of arcs, enables fishermen to identify suitable targets and lower their baits or lures to the correct depth.

A fish-finder works by transmitting an electrical impulse which is converted into a sound wave by a transducer or hydrophone mounted on the underside of the hull and sent into the water. When the sound wave strikes something such as a fish, it is reflected back and displays size, composition and shape. The level of detail and precision depends on the frequency and power of the pulse transmitted. The signal is amplified and sent to the display unit which graphically represents the distance to the fish that reflected the wave.

While the boat is underway, the fish-finder’s display in the pilot house will show you what you cannot see with your own eyes: the presence of fish underwater and their size and location, right down to the ocean floor. 

A fish-finder is an essential electronic tool to enable fishermen to maximise the efficiency and enjoyment of each on-the-water excursion. They are used by both the commercial and leisure fishing sectors and in crafts of all sizes and descriptions.

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