How to Boost the Signal of a Fish Finder

Fish finders display the location of fish underwater.

Fish finders use a transmitter and transducer to display fish and underwater obstructions on a display. If your fish finder is producing images that look nothing like fish, a weak signal may be to blame. You can make changes to the fish finder's settings on deck to resolve the problem. In some cases, however, you must change the transducer angle or mount location.

Things You'll Need

• Fish finder owner's manual
• Drill
• Marine grade sealant

Instructions

1. Adjust the sensitivity on your fish finder. Some fish finders are equipped with Advanced Signal Processing (ASP). Check the owner's manual to verify your fish finder has ASP. Turning on ASP or adjusting sonar sensitivity will change the signal and produce a different display. Play with the adjustment until the resolution is correct.

2. Slow down the boat for a better fish finder signal. At high speeds, the sonar cannot bounce the signal off underwater objects fast enough to produce good fish images. Trolling speeds will likely produce the best fish images.

3. Adjust the transducer angle. The fish finder's transducer transforms electrical signals into information the display can read as fish. Transducers need to be positioned perpendicular to the water to produce the best images. If the transducer is mounted on the boat's transom, loosen the mounting screws with a drill and adjust the angle to perpendicular. If you're using a thru-hull installation, you may need to move the transducer for a better signal. Use marine grade sealant to fill all holes from the previous mount.

4. Tweak display pixels to produce a better signal. In some cases the signal is strong but the display is not converting those signals to fish arches or images. Pixels make up the on-screen picture. Low pixels per square inch tend to produce a grainy image while higher pixels per square inch product a more detailed picture.

Tips & Warnings

• If the transducers mount requires movement, fill all holes with marine-grade sealant to waterproof the hull or transom.

Resources

• Lowrance: Sonar Tutorial