Garmin GNX 21 Instrument Display, NMEA 2000, 4in Display

Overview

The Garmin 010-N1142-10 is a GNX 21 marine instrument display with an inverted 4 inch monochrome LCD (white or color digits on a black background) for showing key boat data at the helm or nav station. It runs on 10 to 32 V and is rated IPX7, with a fully-gasketed polycarbonate case and an anti-glare glass lens for life in the cockpit.

On a NMEA 2000 network it can show sensor and system data such as depth, speed, wind, heading, and battery voltage, depending on what is installed on the boat. The screen layout is flexible, with options to show one reading large or split the page into two or three fields, plus graphs on supported pages. An optional NMEA 0183 data cable can be used to bring in data from a single NMEA 0183 talker.

Key features

• Inverted 4 inch monochrome LCD with maximum digit height up to 36.4 mm for quick reads from a few feet away
• Supports single-field, dual-field, and triple-field layouts, plus graph pages for trending data
• NMEA 2000 and NMEA 0183 compatible (NMEA 0183 input requires an optional data cable)
• 10 to 32 V input, with low typical power use (about 0.35 W daytime and 0.4 W at night) and 1.35 W max
• IPX7 water resistance with a fully-gasketed polycarbonate housing and anti-glare glass lens
• Dimensions without sun cover: 110 x 115 x 30 mm (4.33 x 4.53 x 1.18 in.)
• Compass-safe distance: 209 mm (8.25 in.) to help plan a clean dash layout
• Can share backlight and color settings across NMEA 2000 or NMEA 0183 networks

Compatibility and fit

This display is best thought of as a repeater and organizer for the data already on your boat. What you see depends on the sensors and sources available on your NMEA 2000 backbone or through the connected NMEA 0183 device. If you have Nexus instruments and sensors, data can be brought into the system using a GND 10 bridge (sold separately).

For viewing comfort, plan the mounting angle so the screen stays within a reasonable line of sight. For the GNX 21 inverted LCD, mounting at less than a 50 degree viewing angle helps avoid color inversion when you are off to the side.

Installation and setup

The unit supports flush or flat mounting on a dash panel. For flush installs, a 90 mm (3.5 in.) hole saw cutout is used, and the mounting surface should be flat so the bezel seats evenly and the case is not stressed when tightened.

When mounting in a wet area, use a proper marine sealant around the gasket line to keep water from finding its way behind the dashboard. Unused connectors should remain capped to protect the contacts from corrosion.

Electrical and network integration

Power and NMEA 2000 data both come from the NMEA 2000 network connection, so the backbone needs to be wired and terminated correctly. If the network power wiring is unknown or mixed between brands, isolating the NMEA 2000 power feed can help prevent ground and power issues.

For battery management, it helps to have the NMEA 2000 network powered through an ignition circuit or an in-line switch instead of leaving the backbone energized at all times.

Use on board

This is a good match for boats that want a dedicated instrument screen that stays readable in bright sun and at night without tying up a chartplotter window. It works well on sailboats where wind and speed pages are always in view, and on powerboats where depth, speed over ground, heading, and battery voltage are the everyday checks.

With low typical power draw, it also makes sense for boats that spend time on the hook and still want a clear cockpit readout while running off house batteries.

Maintenance and care

Rinse salt spray with fresh water and wipe the lens with a soft cloth to keep the anti-glare surface clean. During seasonal checks, inspect the dash seal and mounting fasteners, especially if the panel sees vibration or frequent washdowns.

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Customers are responsible for arranging and paying for return shipping unless the return is due to an error by Apollo Lighting or the item is verified as defective, damaged, or incorrect. Missing, damaged, defective, or incorrect items must be reported within 2 business days of delivery, and photos or other documentation may be required for review. If the issue is verified, Apollo Lighting may provide or reimburse return shipping and issue a replacement or refund depending on the circumstances. International customers are responsible for return shipping, duties, taxes, customs charges, brokerage fees, and other costs associated with an international return.

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Many products sold by Apollo Lighting include a manufacturer's warranty covering defects in materials or workmanship. Warranty terms vary by brand, product category, and model, so eligibility, coverage duration, exclusions, and available remedies are determined by the applicable manufacturer. We recommend reviewing the warranty information provided with your product before installation or use, especially for marine electronics, navigation equipment, lighting, electrical systems, pumps, safety equipment, and other specialized marine products.

If you need warranty service, the claim must follow the process established by the manufacturer, authorized service center, or designated warranty provider. You may be asked for proof of purchase, a serial number, product registration, photos, maintenance or installation records, or other documentation. Apollo Lighting does not determine or modify a manufacturer's warranty coverage or final claim decision, but we are happy to help provide purchase information and direct you to the appropriate manufacturer or warranty resource.

Keep your receipt, product documentation, serial number information, and original packaging when practical. Damage caused by normal wear, misuse, improper installation, insufficient maintenance, corrosion, impact, unauthorized modifications, electrical issues, or operation outside the manufacturer's specifications may not be covered. Warranty claims are separate from standard returns, so a product that has been installed, used, or exposed to marine conditions may no longer qualify for return while still remaining eligible for evaluation under the manufacturer's applicable warranty.

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