Garmin GT36UHD-TM, GT56UHD-TM Installation manual

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.

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 anti­fouling paint to prevent marine growth.

Lightly sand the transducer and mounting hardware with a

1

fine-grit abrasive pad.
Wipe the transducer and mounting hardware with isopropyl

2

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

3

mounting hardware.

Installing the Transducer on a Transom

Mounting Location Considerations

• The transducer should be mounted parallel to the water line
.

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.

• 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 v2February 2021

The transducer must be in clean (non-turbulent) water for
optimal performance.

• On single-drive boats, the transducer must not be mounted in
the path of the propeller.

The transducer can cause cavitation that can degrade the
performance of the boat and damage the propeller.

• On twin-drive boats, the transducer should be mounted
between the drives, if possible.

• Mount the transducer cable cover well above the water line

.

• Apply marine sealant to all screw threads to prevent water
from seeping into the transom .

• This transducer has an integrated spray guard, but if your
transducer throws an excessive amount of water spray,
recheck these mounting considerations and adjust the
position of the transducer as needed to eliminate the spray.

Assembling the Transducer with a Transom Mount Bracket

Attach the mount to the transducer with the included

1

star washers , and screws .

Mark the center location of the two holes of the template.

4

Remove the template from the transom.

5

Wrap a piece of tape around a 4 mm (5/32 in.) bit at 18 mm

6

(7/10 in.) from the point of the bit, to avoid drilling the pilot
holes too deep.

If you are installing the bracket on fiberglass, place a piece of

7

tape over the pilot-hole location to reduce cracking of the gel
coat.

Using the 4 mm (5/32 in.) bit, drill the pilot holes approximately

8

18 mm (7/10 in.) deep at the marked locations.
Apply marine sealant to the included 20 mm screws, and

9

attach the transducer assembly to the transom.
Route the cable under the transom mount cable hook.

10

Attach the mount to the bracket with the bolt , flat

2

washer , rubber washer , and lock nut .
NOTE: The bolt should be tight enough to hold the

transducer in place when the boat moves at high speed, but
loose enough to allow the transducer to pivot out of the way if
the transducer hits an obstruction.

Installing the Transom-Mount Hardware

NOTICE

If you are mounting the bracket on fiberglass with screws, it is
recommended to use a countersink bit to drill a clearance
counterbore through only the top gel-coat layer. This will help to
avoid cracking in the gel-coat layer when the screws are
tightened.

The cables connected to the transducer should not be cut,
because cutting the transducer cables voids your warranty.

Choose an installation location on the transom (Mounting

1

Location Considerations, page 1).

Cut out the template.

2

With the template aligned vertically on the transom at the

3

installation location (Mounting Location Considerations,

page 1), place the bottom corner of the template on the

edge of the transom.

If you must route the cable through the transom, choose a

11

pilot-hole location well above the waterline and mark it.
Place a cable clamp on the transducer cable, approximately

12

halfway between the transducer and the top of the transom or
the pass-through pilot hole.

Mark the pilot-hole location for the cable clamp, and using a

13

3.2 mm (1/8 in.) bit, drill a pilot hole approximately 10 mm
(3/8 in.) deep.

Apply marine sealant to the included 12 mm screw, and

14

attach the cable clamp to the transom.
If you marked a pilot hole in step 11, use a 25 mm (1 in.) drill

15

bit to drill a pass-through hole completely through the
transom.

Route the transducer cable to the chartplotter:

16

• If you are routing the cable using a pass-through hole,
push it through the pass-through hole, and install the
cable-entry cover (Installing the Cable-Entry Cover,

page 2).

• If you are not routing the cable using a pass-through hole,
route the cable up and over the top of the transom.

You should avoid routing the cable close to electrical wires or
other sources of electrical interference.

Installing the Cable-Entry Cover

If you routed the cable through the transom after you installed
the transducer, you should install the cable-entry cover to keep
water from entering your boat.

2