Deciphering Bottom Hardness With Your Flasher

When it comes to catching bass from structure, nothing is more important than the electronics mounted to the boat. One of the best tricks I've learned using a flasher is deciphering soft bottoms (muck, clay, fine sand) from hard bottoms (sand/gravel, chuck rock, boulders). Bass often show a preference for one or the other, but usually the harder bottoms. Therefore vast amounts of fishless water can be avoided simply by using your electronics to guide you to the appropriate bottom type.

Reading bottom types is done by observing the signal strength on the flasher. Soft bottoms tend to absorb a certain amount of the sonar's signal, while hard bottoms bounce back a greater percentage of the signal. Therefore the resulting signal of the flasher will reflect these differences. Hard bottoms will be displayed on the flasher as having a wider band of red, while soft bottoms will show as a narrower green band. The other tell-tale sign of a hard bottom is the appearance of a double-echo. This second echo occurs anytime the flasher passes over a hard bottom. It appears on the sonar simply as another bottom reading twice the depth as the true bottom reading. For example, if you're positioned over a ten foot gravel bar, a band will be displayed at ten feet on the sonar, while another slightly less intense band occurs at twenty feet. This band at twenty feet is the double echo.

Avoid changing the gain when trying to interpret bottom hardness, because the gain affects the intensity of the signal. Adjusting it high will result in a strong signal on the sonar, while a low setting will display a signal of less intensity. Continually adjusting the gain will leave you without a base signal from which to compare all other signals to. Find a setting for the gain when you first head out on the lake and then leave it alone. Thereafter, any changes to the flasher's signal as you travel across the water can be attributed to changes in bottom hardness.

Jim Moynagh