Flasher fish finders use sonar technology to locate structure, bottom composition and depth directly below the transducer. Flasher fish finders consist of two main components: the control head and the transducer. As you suspend the transducer beneath the water -- or underneath the ice if you are ice fishing -- it receives sound wave signals. These are converted and displayed on the flasher's dial to help you locate fish.
Experiment with the key functions on your flasher fish finder. Functions vary per model, but many include a flasher dial, range scale, active display, selection dial, color key, target key, zoom key, backlight key, battery key and power or range dial.
Turn on the device by turning the range dial to any setting. Set the depth range, or opt for auto range. Wait for the flasher fish finder to enter normal operation. Sonar return signals will appear on the flasher's dial.
Look at the display and the multiple color palettes on the flasher's dial. These will vary depending on your model.
Understand the color lines on the dial. The line thickness and color reflect the strength of the sonar return, or the size and density of the object under water. Objects can be fish, structures or vegetation. The color palettes will depend on your specific unit model. Red usually means strong, yellow means medium and green means weak sonar-return signals.
Read the numbers on the dial in a clockwise direction. The top of the dial is zero, which represents the top or surface of the water column. The further you read around the dial, the deeper the water column. The unit of measurement may vary per model, but it is typically displayed in feet.
Look at the sonar-return signal colors displayed between zero and the bottom. The bottom is usually indicated by a thick, red line. This is because the bottom is often a dense and hard object which results in a strong sonar-return signal.
Find fish depending on the depth and activity reading of the dial display. Find the depth where the fish are located; adjust your fishing pole and lure based on the information. If the dial is showing a thick, yellow line pointing at 8 feet, adjust your fishing techniques to target that area. The yellow line likely indicates a school of fish.