A New Type Of Fishing Tools

The rise of fishfinders chartplotters has definitely brought changes to the way people catch fish. Before, fishermen relied only on clues that the water and the world gave them in finding a good place where they could go fishing. But now, high tech fish-finders like e.g. the humminbird 798c or the raymarine a70d have brought more excitement and fun to fishing adventures, providing anglers with more information about what's beneath the water.

A kind of fathometer, a fishfinder is a specialized type of echo sounding system that makes use of active sonar to detect fish and the surface and displays them on a CRT or LCD screen. This technology, which can also measure the depth of the water, generally works by converting an electrical impulse coming from a transmitter into a sound waves and sending the waves into the water. Once the sound waves hit something, they are reflected back and show the size, shape and composition of the object. The power and frequency of the transmitted pulse determine the correct extent of what can be detected.

Fishfinders normally come with a "Fish Symbol" feature; this displays a FISH symbol for any echo not attached to the surface or bottom. More specialized fishfinders have the capability to detect living or even dead fish thanks to a detection of a special type of fingerprint in echosignals.

If the Fish Symbol feature is disabled, anglers can learn to differentiate fish, debris, schools of forage fish or baitfish, or vegetation, among other things. Fish normally appears on the screen as an arch due to the changes in the distance between the transducer (the device that changes electrical impulse into sound waves), as the fish swims underneath the boat or as the boat passes over them. A display pixel will be turned on once the fish goes through the sonar beam's leading edge. The pixels are turned on at shallower depths when the fish swims in the direction of the beam center. Deeper pixels will be shown if the distance between the fish and transducer increases, while thicker line will be displayed if the fish is closer to the boat.

With the displayed images on the screen, anglers can identify ideal targets and lower their lures or baits to the right depth. The display on the screen allows them to differentiate between the fish they are aiming at and the bait fish.

Fishfinders came to existence after the integration between fathometers and CRTs for commercial fishing. Nowadays, there are a few big players in the fishfinder manufacturing game, namely Humminbird, Raymarine, or Garmin (GPS). Fishfinding fathometers eventually hit the sporting market thanks to the high power requirements of CRT brought about by the advent of huge LCD arrays. Currently, sporting fishfinders do not yet have a permanent record of the large ship navigation fathometer, which is only available in high end units.