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GT36UHD/GT56UHD 

TRANSDUCERS

INSTALLATION 

INSTRUCTIONS

Important Safety Information

 WARNING

See the 

Important Safety and Product Information

 guide in the 

chartplotter or fishfinder product box for product warnings and 

other important information.
You are responsible for the safe and prudent operation of your 

vessel. Sonar is a tool that enhances your awareness of the 

water beneath your boat. It does not relieve you of the 

responsibility of observing the water around your boat as you 

navigate.

 CAUTION

Failure to install and maintain this equipment in accordance with 

these instructions could result in damage or injury.
To avoid possible personal injury, always wear safety goggles, 

ear protection, and a dust mask when drilling, cutting, or 

sanding.

NOTICE

When drilling or cutting, always check what is on the opposite 

side of the surface to avoid damaging the vessel.

To obtain the best performance and to avoid damage to your 

boat, you must install the Garmin

®

 device according to these 

instructions.
Read all installation instructions before proceeding with the 

installation. If you experience difficulty during the installation, go 

to 

support.garmin.com

 for more information.

Software Update

You must update the Garmin chartplotter software when you 

install this device. For instructions on updating the software, see 

your chartplotter owner's manual at 

support.garmin.com

.

Tools Needed

• Number 2 Phillips screwdriver

Transom mount

• Drill
• Drill bits: 4 mm (

5

/

32

 in.), 3.2 mm (

1

/

8

 in.), 25 mm (1 in.)

• Masking tape
• Marine sealant

Trolling motor mount

• Waterproof tape

Mounting Considerations

To ensure peak performance with the lowest noise and 

interference, you should route the transducer cable away from 

ignition wires, house batteries and wires, trolling motor batteries 

and wires, and high-energy wires such as radar, audio amplifier, 

and autopilot pump wires.

If your transducer cable is not long enough to reach the 

chartplotter, you can add an extension cable (Garmin part 

number 010-11617-42 or 010-11617-32, not included). To avoid 

signal degradation, do not extend the cable more than 9 m (30 

ft.).

Preparing the Transducer for Long-Term Exposure to 

Water

NOTICE

Do not use acetone or acetone-based products on the 

transducer. Acetone damages the plastic transducer housing.

When you install a transducer on a boat that spends a 

significant amount of time in the water, you should coat the 

transducer and mounting hardware with a water-based anti-

fouling paint to prevent marine growth.

1

Lightly sand the transducer and mounting hardware with a 

fine-grit abrasive pad.

2

Wipe the transducer and mounting hardware with isopropyl 

alcohol.

3

Apply water-based anti-fouling paint to the transducer and 

mounting hardware.

Installing the Transducer on a Transom

Mounting Location Considerations

• The transducer should be mounted parallel to the water line 

.

• The transducer should extend 3.5 mm (0.125 in.) below a 

fiberglass hull or 10 mm (0.375 in.) below an aluminum hull 

.

• On boats with outboard or inboard/outboard motors, the 

transducer should be mounted as close to the centerline of 

the transom as possible but at least 38 cm (15 in.) from the 

propeller  .

• If your propeller moves clockwise when the boat moves, the 

transducer should be mounted on the starboard side (right 

side when facing forward).

• If your propeller moves counter-clockwise when the boat 

moves, the transducer should be mounted on the port side 

(left side when facing forward).

• The transducer should not be mounted behind strakes, struts, 

fittings, water intake or discharge ports, or anything that 

creates air bubbles or causes the water to become turbulent.

GUID-24516B07-7980-45F4-972C-79F74FE21812 v1

October 2020

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