Garmin GNX 20 GNX 2021 Installation Instructions

GNX

™

20/21 Installation Instructions

To obtain the best possible performance, install this marine

instrument according to these instructions. If you experience

difficulty during the installation, contact Garmin

®

Support, or seek

the advice of a professional installer.

This instrument communicates with NMEA 2000

®

sensors and

devices, and shows information such as speed, heading, and

water depth when connected to the appropriate sensors. The

instrument can also communicate with a NMEA

®

0183 device

using an optional data cable.

Important Safety Information

WARNING

See the

Important Safety and Product Information

guide in the

product box for product warnings and other important

information.

CAUTION

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.

Mounting Considerations

NOTICE

This device should be mounted in a location that is not exposed

to extreme temperatures or conditions. The temperature range

for this device is listed in the product specifications. Extended

exposure to temperatures exceeding the specified temperature

range, in storage or operating conditions, may cause device

failure. Extreme-temperature-induced damage and related

consequences are not covered by the warranty.

The mounting surface must be flat to avoid damaging the device

when it is mounted.

When selecting a mounting location, observe these

considerations.

•

The mounting location should be at or below eye level to

provide optimal viewing as you operate your vessel.

•

The mounting location should be at less than a 45° viewing

angle for the GNX 20 Marine Instrument with Standard LCD

and less than a 50° viewing angle for the GNX 21 Marine

Instrument with Inverted LCD. Screen color inversion occurs

when the viewing angle is greater than 30° in the 9 o'clock

direction on the GNX 20 and when the viewing angle is

greater than 60° in the 1 o'clock direction on the GNX 21.

•

The mounting surface must be strong enough to support the

weight of the device and protect it from excessive vibration or

shock.

•

To avoid interference with a magnetic compass, the device

should not be installed closer to a compass than the

compass-safe distance value listed in the product

specifications.

•

The area behind the mounting surface must allow room for

the routing and connection of the cables.

Mounting the Device

NOTICE

If you are mounting the device in fiberglass, when drilling the

pilot holes, 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 included template and hardware can be used to flush mount

the device in your dashboard.

1

Trim the flush-mount template and ensure it fits in the

location where you plan to mount the marine instrument.

The flush-mount template is included in the product box.

2

Remove the liner from the adhesive on the back of the

template and adhere it to the location where you plan to

mount the marine instrument.

3

If you plan to cut the hole using a rotary tool instead of a

90 mm (3.5 in.) hole saw, use a 10 mm (

3

/

8

in.) drill bit to drill

a pilot hole to begin cutting the mounting surface.

4

Using the 90 mm (3.5 in.) hole saw or rotary tool, cut the

mounting surface along the inside of the dashed line

indicated on the flush-mount template.

5

If necessary, use a file and sandpaper to refine the size of

the hole.

6

Place the marine instrument into the cutout to confirm that

the mounting holes on the template are in the correct

locations.

7

If the mounting holes are not correct, mark the correct

locations of the mounting holes.

8

Remove the marine instrument from the cutout.

9

Drill the 2.8 mm (

7

/

64

in.) pilot holes.

If you are mounting the marine instrument in fiberglass, use a

countersink bit as advised in the notice.

10

Remove the remainder of the template.

11

Place the included gasket on the back of the device and

apply marine sealant around the gasket to prevent leakage

behind the dashboard.

12

If you will not have access to the back of the device after you

mount it, connect all necessary cables to the device before

placing it into the cutout.

NOTE:

To prevent corrosion of the metal contacts, cover

unused connectors with the attached weather caps.

13

Place the marine instrument into the cutout.

14

Securely fasten the marine instrument to the mounting

surface using the supplied screws.

If you are mounting the marine instrument in fiberglass, use a

anti-galling lubricant as advised in the notice.

15

Snap the bezel

into place.

GUID-E313CF8B-397D-48AF-8839-977C29E188D5 v4

August 2020

Section	Page
GNX 20/21 Installation Instructions	1
Important Safety Information	1
Mounting Considerations	1
Mounting the Device	1
Connection Considerations	2
NMEA 2000 Connection Considerations	2
NMEA 0183 Connection Considerations	2
NMEA 0183 Connection Diagrams	3
Specifications	3
NMEA 2000 PGN Information	3

Garmin GNX 20 GNX 2021 Installation Instructions

Garmin GNX 20 Manual

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