Tips on Fishfinder Use

Tips on Fishfinder Use
So you have your fishfinder and every now and then a little fish symbol floats across the screen. If you're thinking there must be more to it than that, you're right. Fishfinders, or sonar units, are used to locate the type of bottom structure that attracts fish. They are also used to locate sharp changes in water depth, and schools of baitfish. While your fishfinder will work right out of the box, a little understanding will go a long way toward getting the most out of your machine.

Auto Settings

Default settings for your sonar are programmed so that the unit can be used by a novice. Your fishfinder will automatically lock on the bottom, and fish will be displayed as fish-shaped icons instead of the actual arc reflections picked up by the sonar. The problem with the fish icons is that the machine is easily fooled. Sometimes fishfinders interpret sub-surface debris or turbulence as fish. Turn off the Fish I.D. feature and start getting used to looking at arcs.



Your fishfinder works by sending out a sound through the transducer, and then recording its reflection which is then displayed on the monitor. The reflections are displayed in arc-shaped lines. The stronger the reflection, the larger the arc. Schools of baitfish show up as a solid mass.


By increasing the sensitivity, you magnify all reflections. The limiting factor of this feature is the clutter that comes back when the tiny reflections of junk in the water are magnified.


Your machine goes beyond telling you how deep the water is, or how bumpy the bottom is; it also tells you whether the bottom is hard or soft. Your fishfinder displays the bottom as a solid line. A thin line indicates a hard bottom, while a thick line tells you that the bottom is soft mud or sand.


The zoom feature on your fishfinder lets you zoom in on a section of the water column. When you zoom in on the bottom, you get a better view of the detail on the bottom, including wrecks and fish. You can split your screen and have both views simultaneously.


Article Written By Stephen Byrne

Stephen Byrne is a freelance writer with published articles in "Nor'East Saltwater," "Sportfishing" magazine, "Pacific Coast Sportfishing" and "Salt Water Sportsman." As a fishing charter captain, he was also interviewed for a feature in "Field and Stream." Byrne studied environmental science at the State University of New York at Delhi.

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