Sonar Mastery Article Posted on June 02, 2013
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We rarely see fish on drop-offs because the closest “bottom” to the transducer is the drop-off, so the fish are not displayed. Sonar displays the echo strength of the target and the distance the target is from the transducer. The first example has the fish a farther distance from the transducer than the bottom so the fish echo is added to the “bottom“ echo and not seen. The “bottom” under the transducer is 25 ft, fish at 23 ft, and the drop off “bottom” is 20 ft. Now visualize what the sonar will show you. The picture is my rough drawing so it is not to scale; it is just to get you thinking.
If you can’t find fish near the bottom with sonar - you can’t catch them! I will show you one way to find hidden fish.
Fish close to the bottom are sometimes displayed as bumps. You have 2 ways to decide if a bump on the bottom is a fish. You can drop an underwater camera or use high definition color sonar. Fish return weaker echoes so they display a different color than the bottom depending on the setting of your colorline and sensitivity.
We will compare the freshwater HDS frequencies plus how to eliminate cross talk.
