The GMI 40 does not immediately replace the well-known GMI 20 in Garmin’s range of instruments for every application, but it places significantly greater emphasis on modern touchscreen operation and freely configurable displays. It is therefore aimed not only at sailors, but also at motorboat enthusiasts who want to be able to read individual readings clearly from the helm without having to constantly look at the chartplotter.
More space for on-board data
The instrument measures 115 by 91 by 30 millimetres and weighs 250 grams. Its high-resolution colour display has a resolution of 800 by 480 pixels. Various instrument clusters and page layouts can be configured on the screen. Depending on the connectivity, this allows data such as engine speed, engine temperature and fuel levels to be displayed, as well as GPS position, course over ground, water temperature or depth.
The practical difference compared with the previous Garmin GMI 20 lies primarily in the way they are operated: the older model features buttons and a four-inch colour display, whilst the GMI 40 has a touchscreen and a slightly larger display. For owners who wish to continue using existing cut-outs in the helm, Garmin offers a mounting plate.
Connected to the Garmin system
For on-board integration, the GMI 40 features NMEA 2000 and Garmin BlueNet. According to the manufacturer, it can also communicate wirelessly with gWind wireless transmitters, marine remote controls and quatix marine smartwatches. Software updates can be installed via the ActiveCaptain app.
For motorboat owners, the key benefit is the display of engine and fuel data. The additional instrument can keep important readings constantly visible, whilst the chartplotter remains free for navigation, radar or echo sounder displays. Anyone who already uses a recent Garmin chartplotter, for example from the GPSMAP 9000 Series, the GMI 40 can be incorporated as a compact addition to the driver’s cab.
As well as the standalone unit, Garmin offers several bundles including wind, depth and speed transducers. The Wired and Wireless Sail bundles combine one or two displays with gWind transducers and, depending on the variant, either a DST820 Smart transducer or the GDT 43 and GST 43 through-hull transducers. The DST820 not only measures depth, speed and water temperature but, according to Garmin, also records data on heel, trim, and heave and roll movements. With the wireless version, there is no need to run cables through the mast for lengths of up to 15 metres.
The Garmin GMI 40 costs around 700 euros as a standalone unit. Depending on the features included, the bundles cost between 1,200 and 2,100 euros.
Technical Specifications
| Characteristic | Garmin GMI 40 |
| Display | 4.3-inch colour touchscreen, 800 x 480 px |
| Dimensions | 115 × 91 × 30 mm |
| Weight | 250 g |
| Networking | NMEA 2000, Garmin BlueNet, ANT+, Wi-Fi |
| Protection class | IPX7 |
| Data | Wind, speed, depth, course, engine, fuel |
| EIA | €699.99 |
Anyone who prefers a keyboard instrument or wants to add to an existing Garmin system as cost-effectively as possible will find the Garmin GMI 20 It also features a four-inch colour display and NMEA-2000 connectivity. For wind-only displays, Garmin’s range also includes specialised GNX wind instruments.
Book recommendations
Theory and Practice of Vehicle Electrical Systems explains the on-board electrical system from the ground up, from batteries and charging systems right through to power distribution and troubleshooting. For those retrofitting a multifunction display, the practical guidance on chartplotters, loggers, navigation systems and individual on-board installations is particularly helpful. Diagrams, photographs and tables illustrate the key considerations for the planning, connection and maintenance of on-board electrical systems.
Stress-free navigation focuses on the data that a display such as the GMI 40 can show: position, heading, speed and depth. This guide combines navigation with nautical charts, compasses and GPS, alongside trip planning, weather and tide information. Step-by-step photographs, diagrams and tables help readers to understand the displayed values in a nautical context.
Would a separate multifunction display be useful at your helm, or is the information on the chartplotter sufficient for you? Please let us know which readings you’d like to keep an eye on at all times whilst sailing.
Hauke Schmidt
Test & Technology editor