Fishfinder Terminology


A fishfinders transducer uses sonar to see what is underneath it. When it shoots its sound wave it goes out in a cone shape. Depending on the angle it uses, it might show more or less of the bottom.

For example when you shine a flashlight the light comes out of the but goes out at a certain angle to help the light expand. This is like a fishfinder works because the sound wave goes out with an angle too. The bigger the degrees, the more it stretches out. Some high end fishfinders have up too to 120 to even 150 degree angles of view.


Another important measurement is that of frequency. This is the frequency of the sound wave signal that the fishfinder uses. A lower frequency like 50 kHz is good for deep water and you can go a long distance without splitting apart. A higher frequency like 200 kHz would work very well in a shallow water surface like a lake or pond. Most fishfinders allow you to set the transducer frequency based on your preference for you to find the most fish.


A very useful feature into fishfinder is the ability to tag possible fishes and other marine life on the display. By sensing what kind of sonar is returned from an object, your fishfinder can intelligently guess if it is a fish or not.


On this web site and you’ll run across the term transducer frequently. The transducer is the main sonar device on your fishfinder. It actually shoots the sound beam and listens for the return.

It is very important that you transducer be positioned correctly on your boat. You want to keep it away from your motor. Some transducers are made to be mounted in the water. Some can be mounted on the hull of your boat. Still, some other fishfinders need to be mounted by drilling a hole in your boat.


The display of the fishfinder is the part of the device that you actually look at the sonar results on. Obviously, the larger the screen the easier it will be for you to read it when you are out fishing on your boat.

Some displays are rated with high resolution and have lots of pixels. Some displays come in black and white, others come in color.


One Response to “Fishfinder Terminology”

  1. which fishfinder works best in shallow salt/brackish water. ie at depths of 1 foot. for flats fishing

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