Overview

The Garmin GMI 20 is a marine instrument display that ties into a NMEA 2000 network so you can see live data from sensors and devices around the boat. It runs from the NMEA 2000 backbone (9 to 16 Vdc) and carries an IPX7 water rating for incidental exposure, so it can be mounted on an open helm or inside a pilothouse when the cutout is properly sealed.

This listing covers a range of display options, including compact 4 inch units (110 x 115 x 30 mm without the sun cover) and larger 7 inch and 10 inch screens. Depending on the configuration, the display style may be color, monochrome, or a wind-rose layout, with either a white or black background.

Key features

• NMEA 2000 connection for power and data, with 9 to 16 Vdc input from the network
• IPX7-rated housing and a gasketed polycarbonate case for spray, rain, and routine washdowns
• Glass lens with an anti-glare finish to keep the screen readable in changing light
• 4 inch housing size: 110 x 115 x 30 mm (4.33 x 4.53 x 1.18 in.) without the sun cover
• Large-format sizes extend up to 249 x 153 x 19 mm (9.8 x 6.02 x 0.75 in.) for the 10 inch model
• NMEA 0183 support depends on the configuration: some accept an optional NMEA 0183 data cable, while others rely on NMEA 2000 data sources on the network

Variants

This product is offered in multiple configurations, with the listed options varying by screen size (4 inch, 7 inch, or 10 inch), display type (color, monochrome, or wind rose), and display background (white or black).

All versions are built to live on a NMEA 2000 backbone, so the specific pages and numbers you can show depend on which sensors and data sources are installed and configured on your boat.

Installation and setup

Plan the mounting spot so the surface is flat and strong enough to handle vibration, and make sure you have room behind the panel for cable routing. Flush mounting is common on sailboat pods, instrument panels, and powerboat dashes, and a gasket is used at the rear of the unit to help keep water out of the cutout.

If you are mounting into fiberglass, take your time on the cutout and pilot holes and avoid over-tightening fasteners. A small amount of marine sealant around the gasket area is a practical step to keep water from tracking behind the dashboard.

Network and data sources

These displays get power and data from the NMEA 2000 network. That means your depth, speed, wind, heading, engine, battery, and environmental pages are only as complete as the sensors and gateways you have on the backbone. Some 4 inch configurations can also communicate with a NMEA 0183 device using an optional data cable, while other configurations display NMEA 0183 data only when it is brought onto the NMEA 2000 network through a compatible bridge or networked device.

Compatibility and fit

Before ordering, match the screen size and background style to where you will mount it and how far away you need to read it. If you are installing near a magnetic compass, note that the compact 4 inch housing lists a 209 mm (8.25 in.) compass-safe distance, while the GNX 120/130 large-format models list 0 mm (0 in.).

Use on board

On a sailboat, this kind of display often ends up as the always-on screen for wind, boat speed, depth, and heading in the cockpit. On a powerboat, it is commonly used as a dedicated data screen for depth, fuel, battery status, and engine information that is already on the NMEA 2000 network.

This is a good match for boats that already have a NMEA 2000 backbone and need a dedicated, easy-to-glance instrument display at the helm, nav station, or inside the cabin.

Maintenance and care

After saltwater use, rinse the face and bezel with fresh water and wipe with a soft cloth. Avoid harsh solvents on the lens and bezel, and keep unused connectors capped to reduce corrosion in humid lockers and wet consoles.