How Is Sonar Used In Ice Fishing?

We all know that fishing on the ice is supposed to be challenging and fun. When our ice rods are busy we can achieve both. If the fish aren’t there, however, the fun can dissipate quicker than the ice during a week of warm spring temperatures.

This is why a fish finder (sonar) is considered by so many anglers to be one of the most important pieces of ice fishing equipment that you can own. You have seen the results from their use, but you might be wondering how to achieve them. Let’s take a closer look at how sonar is used in ice fishing and see how!

How Does Sonar Work Out On The Ice?

The sonar equipment that sports fishermen use emits a signal from its transducer or hydrophone. That signal is converted to a sound wave that travels through the water below the ice until it hits something. The wave is reflected back to the sonar device where it is converted into information that we can see and interpret.

Hydrophones are designed to operate under the water’s surface, so the ice will create interference and block the signal. A hole must be augured through the ice so that the transducer can be placed in the water. Experience has taught that a separate hole from the one I am fishing out of is best unless you want to lose the fish and reel in the sonar equipment instead!

Today, we can choose from an array of fish finders that provide different forms of data and features. The trick is finding the right one for you. There are two main categories of sonar units used on the ice; flashers and LCD units.

Flasher-Type Sonars

These were the first type of portable sonar that sports fishermen used while out on the water, beginning in the 1970s. By the early-80s they found their way onto the ice. While they may be more difficult to interpret when compared to LCD-type sonars, learning to use them correctly ( can produce lots of fish through the ice.

Flashers use a circular display to provide you with information. The dial represents the water column under the transducer, with 12-o’clock representing the water just below the ice. Each signal that is received will be displayed farther down the dial (clockwise) away from that point.

The water’s depth is indicated by referencing the numbers printed on the face of the flasher. Information that is gathered by a flasher comes from the cone-shaped signal broadcast from the hydrophone. These devices use multiple colors and intensities of those colors to display an object as well as indicate the strength of the signal received from it.

A brighter signal lets you know that an object is near the center of the sonar cone. Conversely, a dimmer signal indicates that it is closer to the edge of the cone. These signals can be adjusted through controls for cone-angle, depth, and gain.

Keeping the depth setting as close to the water’s depth under the ice is critical for displaying an accurate picture of what is going on below the hole. Fine tuning the gain will help to eliminate interference and provide more resolution between signals. I’m a visual learner, so I will direct you to this video ( showing a flasher in action.

LCD-Type Sonars

By the mid-1980s technology had advanced to the point that portable sonars started to use screens to display data instead of lights on dial displays. While the scrolling screen information was intended for use on a boat, it didn’t take long for these devices to become part of the ice fishermen’s arsenal. A liquid display can provide lots of information and details ( that will help you improve your luck on the ice.

Images displayed on the LCD screen will show a side or top-down view of the data received by the sonar cone. Information may be displayed in gradients of single colors (such as green) or in multiple colors. With most LCD sonars, fish are indicated by an arc on the screen.

Water depth is marked on the side of the image, with the bottom of the lake running along the lower portion of the screen. With color displays, variances along the bottom can help to identify the substrate make-up and showcase rockpiles or vegetation. Arcs or symbols that indicate fish can be shown in different sizes that reflect the size of the fish that reflects the sound wave.

One feature that LCD sonars provide is scrolling. This feature updates the positions of objects in the cone and provides a history of the signals received. A variety of controls can adjust the depth, gain, and image orientation. For those of us who like visuals, this video showing LCD screens is worth a look.

There are plenty of resources online that can help narrow your search. Visiting a retailer gives you some hands-on feedback as well. No matter what type of sonar you get, remember that having a fish finder on the ice is better than having none at all!