Garmin GNX 21 Marine Instrument

  • $692.10
    Unit price per 
Tax included.

PART NUMBER: 010-01142-10

The easy-to-read GNX 21 marine instrument has an inverted display with white or colour digits on a black background that clearly shows depth, speed, wind and 50-plus marine and boat parameters. Its glass-bonded display with anti-glare lens coating provides excellent daytime and nighttime readability with high-contrast digits scalable up to 36 mm.

The GNX 21 is the first glass-bonded marine instrument with a combination of directly driven LCD segments and a dot-matrix field to display graphical information. Its low power consumption — (25 mA) with 350 mW (no backlight)/400 mW (mid-level backlight) — is perfect for use on sailboats, and provides a valuable instrument for cruising and fishing. Fully customisable user profiles display wind, depth and speed data. Plus, the GNX 21 includes an auto-scroll feature that rotates through data screens for hands-free operation. It can be installed with the included low profile flush mount or an optional flat mount for the ultimate glass helm solution and custom look for your boat.

¹Colour backlight is not visible in daylight.

Physical & Performance

Physical dimensions 110 x 115 x 30 mm (4.33" x 4.53" x 1.18")
Voltage range 9-16 V (from NMEA 2000)
Mounting options Flat or Flush
Display size

83 x 60 mm; 101.6 mm diagonal

(3.3” x 2.4”; 4.0” diagonal)

Water rating IPX7
Weight 230 g (8 oz)
Display type Inverted LCD, monochrome


User profiles Yes
Glass bonded display yes
Power consumption

0.35 W (day); 0.4 W (night)

Compass-safe distance 209 mm (8.25 in.)
NMEA 0183 compatible Yes
Temperature range From 5° to 158°F (from -15° to 70°C)
NMEA 2000® certified yes



In the Box

  • GNX 21
  • Trim piece snap cover
  • Protective cover
  • Flush mount gasket and hardware
  • NMEA 2000® T-connector
  • NMEA 2000 drop cable
  • Installation instructions
  • Documentation