Split Screens

Before delving into sensitivity, colorline, and so forth, consider your fishing style. Are you structure-fishing or setting up a trolling spread for open water? For structure, try switching your unit to split-screen zoom mode. That way, the nuances of bottom are displayed on both sides of the screen. Moreover, the zoom window is powerful enough to pick out individual fish lying on bottom. Dropping a jig in the unit’s cone angle shows your presentation in relationship to the fish, perhaps even their approach toward it. You can mark crappies in zoom mode and watch them rise off bottom or out of a school to inspect and strike bait.

On the other hand, full-screen mode is preferable for the wide-screen view of what lies below. It’s possible to go into the “sonar setup” menu to create upper and lower depth limits to read specific bands—say, 20 to 40 feet—to zero in on bait and fish with greater accuracy. If you primarily troll, however, split-screen mode may not be for you—wide-screen view is better for this application.

Colorlines

Next up: The crucial setting of sensitivity. While it was once important to crank the sensitivity almost to 100 percent with black-and-white units, color screens operating with higher power levels no longer require full-tilt sensitivity. Rather, the best way to set it is to turn it up until clutter and distortion fill the screen to the point of unreadability. Then back off until the screen clears itself of all but a little sprinkling that looks like a dusting of pepper. Then back off one or two more clicks for good measure. You’ll need more sensitivity in deeper water, less in water shallower than 15 feet. Fish show in shades of red and orange, depending on their size and location in relation to the sonar’s cone angle.

That brings us to colorline, the modern version of grayline, once the standard way black-white units provided separation of targets from bottom. On a color screen with colorline, you’re better able to see fish on structure and even in weeds. For most applications, start with a colorline range of 75 to 90 percent, then adjust as needed.

To dial-in specific numbers, experiment with the colorline settings until the bottom shows a black, defining line with yellow underneath it. Then increase the colorline until the yellow has a hint of red in it; reduce the level from there until the red disappears, then increase by a click or two. At this setting, changes in the sonar return indicate both fish and differences in bottom content.