How to Install a Garmin Fishfinder

Updated March 23, 2017

Garmin fishfinders consist of a digital display screen, which depicts sonar and depth information in a graphical format with an ergonomic keypad design. Installing a Garmin fishfinder primarily involves mounting the display unit, installing the transducer, and installing the wiring harness. Although there are many models of Garmin fishfinders, the installation and setup for each individual model is standardized, requiring only minimal diversions from the generalized installation procedures.

Select the location for the Garmin fishfinder. Considerations for the location of your Garmin fishfinder include easy access and viewing during boat operation, sufficient strength for the weight of the fishfinder unit, and adequate space, usually 3 inches, behind the fishfinder to accommodate the wiring harness.

Determine whether the location of your fishfinder will require a horizontal or flush mount. Both mounting assembles are included with the Garmin fishfinder.

Predrill holes for the three screws that will secure the fishfinder mount to your vessel.

Place the fishfinder mount over the pre-drilled holes, aligning the mount's fastener holes over the predrilled screw holes.

Insert the 3, 4 mm bolts through the fishfinder mounts with the washers providing a buffer between the screw heads and the mount assembly. Attach the bolts to the through ends of each screw assembly. Tighten the mount to the vessel using the Phillips screwdriver.

Determine the best location for the transducer unit and connecting cable. The transducer cable should be mounted above the water line with the transducer itself 1/8 inch below a fiberglass hull or 3/8 inch below an aluminum hull. The transducer is the sonar unit and the transducer cable attaches the transducer to the boat hull with the wiring continuing to the fishfinder display unit.

Use the fasteners included in the transducer kit to secure the transducer cable to the stern of the vessel, in accordance with the model's owners manual.

Install the wiring harness in a secure, dry, protected area using the wiring harness kit and specific instructions for your fishfinder model.

Attach both the transducer cable and the fishfinder display cables to the transducer. The wiring harness connects the Garmin fishfinder unit to the transducer and power supply.

Test the Garmin fishfinder installation. Turn on the fishfinder and follow the prompts. If the power supply is not connected, the fishfinder will remain off. In the event the transducer is not properly connected, the message "Transducer Disconnected, Sonar Turned Off" will appear on the display screen.


Consult the owners manual for specific instructions for your fishfinder unit's installation procedures.

Things You'll Need

  • Drill
  • Phillips screwdriver
  • 3, 4-mm pan-head machine bolts with nuts and washers
  • Transducer mounting kit
  • Wiring harness kit
  • Owners manual
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About the Author

Stan Kane is an experienced professional pilot and freelance writer. He enjoys writing about a diverse range of outdoor, science and technology topics. Kane has a Bachelor of Science degree from Florida Tech and has been writing for Demand Studios since 2009.