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2

Install the locking rings on the marine network and power 

cables.

3

Connect the bare-wire end of the power cable to a 12 Vdc 

power source and to ground.

4

Align the notch on the end of the power cable with the power 

port on the device, and press the cable into place.

5

Tighten the locking ring.

6

Select an option:
• If your boat is equipped with a GMS

 10 network port 

expander, connect the network cable to an available port 

on the GMS 10.

• If your boat is not equipped with a GMS 10 network port 

expander, connect the network cable directly to the 

network port on your chartplotter.

Cable Routing Grommets

When routing cables through your boat, it may be necessary to 

drill holes to route the cables. Cable routing grommets can be 

used to cover cable installation holes. The grommets do not 

create a waterproof seal. If necessary, apply a marine sealant 

after installation to weatherproof around the grommet and the 

cable. You can purchase grommets from your Garmin dealer or 

directly from Garmin at 

www.garmin.com

.

Installation Diagram

You can use this diagram to identify the connection points from 

your sounder to the network, power, and transducer.

Item

Description

À

Chartplotter

Á

GSD 25

Â

Power Source

Ã

Transducer

Blink Codes

After the sounder is installed, it turns on when the chartplotter is 

turned on. The two-color (green and red) status LED on the 

sounder indicates its operational status.

LED 
Color

State

Status

Green

Slow blink

The sounder is connected to a chartplotter 
and is operating properly. You should see 
sonar data on the chartplotter.

Red

Slow blink

The sounder is turned on, but is not 
connected to a chartplotter, or is waiting to 
connect to a chartplotter. If the sounder is 
connected to the chartplotter and this code 
persists, check the wiring connections.

Red/
Green

Slow blink

The sounder is in test mode.

Red

Rapid blink 
sequence

System error. The chartplotter displays a 
message indicating the type of failure. When 
the error condition is fixed, the sounder must 
be completely disconnected from and 
reconnected to its power source to clear the 
error.

Red

Solid

The sounder has a hardware failure. Contact 
Garmin Product Support for assistance.

Specifications

Specification

Measurement

Size

W × H × D: 251 x 66 x 192 mm (9.9 x 2.6 x 
7.6 in.)

Weight

771 g (1.7 lb.)

Case material

Fully gasketed, polycarbonate plastic

Water rating*

IEC 60529 IPX7

Temperature range

From -15° to 70°C (from 5° to 158°F)

Power input

From 10 to 35 Vdc

Power usage

27 W maximum

Fuse

4.0 A

Compass safe 
distance

30 cm (11.8 in.)

Transmit power 
(RMS)**

1 kW

Frequency

Traditional sonar: 50/77/83 kHz
Single channel and dual channel CHIRP: 40 kHz 
to 250 kHz
SideVü/DownVü: CHIRP 455/800 kHz and 
260/455 kHz

Depth***

Traditional: 1524 m (5000 ft.); DownVü: 305 m 
(1000 ft.); SideVü: 229 m (750 ft.) left and right.

Data output

Garmin Marine Network

*The device withstands incidental exposure to water of up to 1 m 

for up to 30 min. For more information, go to 

www.garmin.com

/waterrating

.

**Dependent upon transducer rating and depth
***Maximum depth, dependent upon transducer, water salinity, 

bottom type, and other water conditions.

Garmin

®

 and the Garmin logo are trademarks of Garmin Ltd. or its subsidiaries, registered in the USA and other countries. GSD

 is a trademark of Garmin Ltd. or its subsidiaries. These trademarks may not be 

used without the express permission of Garmin.

© 2014 Garmin Ltd. or its subsidiaries

www.garmin.com/support

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