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Installing the Transducer on a Transom

Mounting Location Considerations

• The transducer should be mounted as close to the center of 

the boat as possible.

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

optimal performance.

• The transducer should not be mounted in a location where it 

might be jarred when launching, hauling, or storing.

• 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.

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 any 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.

1

Position the transducer mount 

À

 so the center of the bottom 

of the transducer is level with the bottom edge of the transom 

and is parallel to the water line.

2

Align the transducer parallel to the water line 

Á

, and mark 

the center location of the two outer holes and the center hole 

of the transducer mount.

3

Wrap a piece of tape around a 4 mm (

5

/

32

 in.) bit at 15 mm 

(

19

/

32

 in.) from the point of the bit, to avoid drilling the pilot 

holes too deep.

4

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

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

coat.

5

Using the 4 mm (

5

/

32

 in.) bit, drill the pilot holes 

approximately 15 mm (

19

/

32

 in.) deep at the marked locations.

6

Apply marine sealant to the included 20 mm screws, and 

attach the transducer assembly to the transom.

NOTE: 

A third screw in the lower center screw hole stabilizes 

the mount.

7

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

pilot-hole location well above the waterline 

Ã

 and mark it.

8

Place a cable clamp on the transducer cable 

Ä

approximately one third of the distance between the 

transducer and the top of the transom or the pilot hole.

9

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

3.2 mm (

1

/

8

 in.) bit, drill a pilot hole approximately 10 mm 

(

3

/

8

 in.) deep.

10

Apply marine sealant to the included 12 mm screw, and 

attach the cable clamp to the transom.

11

Repeat steps 10–12 to install the other cable clamp 

approximately two thirds of the distance between the 

transducer and the top of the transom or the pilot hole.

12

If you marked a pilot hole in step 9, use a 25 mm (1 in.) drill 

bit to drill a pass-through hole completely through the 

transom.

13

Route the transducer cable to the sounder:
• If you are routing the cable using a pass-through hole, 

feed it through the hole you drilled in step 14, and install 

the cable-entry cover 

Ã

.

• If you are not routing the cable using a pass-through hole, 

route the cable up and over the top of the transom 

Å

.

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.

1

Place the cable-entry cover 

À

 over the hole and the cable, 

with the opening pointing downward, and mark the location of 

the two pilot holes.

2

Remove the cable-entry cover, and, using a 3.2 mm (

1

/

8

 in.) 

bit, drill the pilot holes approximately 10 mm (

3

/

8

 in.) deep.

3

Fill the pass-through hole with marine sealant so it covers the 

cable completely and there is excess sealant around the hole 

and the cable.

4

Place the cable-entry cover over the hole and the cable, with 

the opening pointing downward.

2

Summary of Contents for GT30-TM

Page 1: ...date to a memory card 1 Insert a memory card into the card slot on the computer 2 Go to www garmin com support software marine html 3 Select Download next to Garmin Marine Network with SD card 4 Read and agree to the terms 5 Select Download 6 If necessary select Run or save and open the file 7 If necessary select the drive associated with the memory card and select Next Finish Updating the Device ...

Page 2: ...2 in deep at the marked locations 6 Apply marine sealant to the included 20 mm screws and attach the transducer assembly to the transom NOTE A third screw in the lower center screw hole stabilizes the mount 7 If you must route the cable through the transom choose a pilot hole location well above the waterline à and mark it 8 Place a cable clamp on the transducer cable Ä approximately one third of ...

Page 3: ...of the boat and put the transducer at risk of striking underwater objects Test the transom mount transducer installation in open water free of obstacles Pay attention to your surroundings as you test the transducer 1 With the boat in the water turn on the chartplotter 2 Drive the boat at a slow speed If the chartplotter appears to be working properly gradually increase speed while observing the ch...

Page 4: ...are trademarks of Garmin Ltd or its subsidiaries registered in the USA and other countries These trademarks may not be used without the express permission of Garmin 2013 2014 Garmin Ltd or its subsidiaries www garmin com support ...

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