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Get more from your sonar.

Although electronics are constantly , changing to better suit the desires of avid walleye anglers, savvy sonar interpretation remains a necessary requirement, and transferring the picture on your sonar display to a cerebral image of the bottom takes practice. Walleye seekers often look for signals that indicate minor nuances--shifts in bottom contours, changes in substrate composition, and abrupt variations in depth; yet finding such potentially fertile areas requires a close relationship between mind and machine.


On a basic level, sonar interpretation is pretty simple. You can power-up most any decent unit and, with very little effort in the way of adjusting the settings, read things like the depth and water temperature--even view wary walleyes lurking below your boat.

Yet as simple as they are to operate, sonar displays are also easy to misinterpret. For instance, as you weave back and forth along a steep drop-off, idling up and down the incline, the display typically shows a series of unmistakable "humps." In reality, there aren't any humps below the hull, just a uniform breakline. But the sonar doesn't know that--it sees humplike changes in depth. And so will you, if you fail to factor the boat's trajectory into the equation.

What sonar doesn't show is equally important. Many accomplished walleye anglers don't fish "spots" as much as they wander the water looking for the right combination of structure, forage, and fish. If the sonar screen remains blank, they believe there's really no reason to drop a line, right? However, there are situations--particularly along steep drop-offs or among large boulders--where fish won't appear on the sonar display but are actually present below your boat.

Anglers often assume their electronics cover complete areas of bottom descent, yet the transducer cone only extends to the uppermost point of bottom contact, creating a dead zone beneath. Narrow-beam transducers work best under these circumstances, since they limit the dead zone instances. But even if your sonar is equipped solely with wide-angle capabilities, there is a simple solution: Travel over your anticipated "hotspot" from multiple angles.

Instead of scooting along transition lines--breaks and drop-offs--on a parallel plane with the depth change, intersect the underwater topography directly. Move the boat in and out, shallow to deep, deep to shallow, allowing opportunity for your sonar to view everything below. Keep a sharp eye on the sonar display. If the transducer cone hits only a small portion of the walleye's body, return signals are shown as a small blob. If the entire fish enters the cone, it appears as a straight line.


Such thorough scouting with the main outboard will tell you if fish are present or not, and whether you should give the spot a try--or put your boat on plane in search of more fertile fishing grounds.

Jason Durham *

* Jason Durham is a guide (, sonar expert, and writer from Park Rapids, Minnesota. Inside
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Title Annotation:ELECTRONIC 'EYES; use of sonar in walleye fishing
Author:Durham, Jason
Publication:Walleye In-Sider
Geographic Code:1USA
Date:May 1, 2009
Previous Article:The case for twistertails.
Next Article:Mud in your 'eye.

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