Garmin is expanding its range of instruments with the GMI 40. The new colour display is designed to consolidate key on-board data in a fixed location in the cockpit, whilst leaving the chartplotter free for nautical charts, AIS, radar or echo sounder images. Those who wish to keep an eye on wind angle, speed through the water, depth and heading all at once whilst at the helm do not need to switch between different plotter screens. The Garmin GMI 40 It features a 4.3-inch colour touchscreen display with a resolution of 800 by 480 pixels. The display can be configured with various data fields and instrument panels.

Wind data where it’s needed

For sailors, the focus is less on engine and fuel readings and more on traditional instrument data. Among other things, the GMI 40 can display apparent and true wind, wind angle, boat speed, depth, water temperature, heading and GPS track.

However, whether the new on-board display is actually of any use depends on the quality of the overall system. An instrument can only display true wind speed if the wind sensor, log and heading source provide suitable data that has been calibrated as accurately as possible. With older systems, owners should therefore first check which sensors, bus systems and converters are already in place before retrofitting. Our overview shows, when ageing systems can be upgraded and when it makes more sense to replace them.

Touchscreen instead of buttons

Compared with the version that is still available Garmin GMI 20 The GMI 40 features touch controls and a slightly larger display. The GMI 20 uses buttons and a four-inch colour display. Garmin offers an adapter plate for upgrading from the GMI 20. It is designed to make installation into an existing cut-out easier.

NMEA 2000 as a prerequisite

The GMI 40 is integrated via NMEA 2000 and Garmin’s BlueNet network. NMEA 2000 is the key standard for retrofitting: transducers and displays are connected to a shared backbone cable and can make their data available on the network. On modern yachts, this is usually straightforward. However, in the case of mixed systems comprising NMEA 0183, SeaTalk, SimNet or older proprietary instruments, it must be clarified in advance whether a converter is required.

An example of such a bridging solution is the Pitufino V1.2, which can consolidate different data protocols. As for the GMI 40 itself: it does not replace any missing sensors, nor does it automatically resolve compatibility issues with older networks. Its primary function is to display the data reliably supplied by the vehicle’s electrical system.

According to Garmin, the instrument can communicate wirelessly with gWind wireless transmitters, marine remote controls and quatix marine smartwatches. Software updates can be installed via the ActiveCaptain app. Integrating a watch can be useful if wind, depth or course data needs to be available whilst manoeuvring at the bow or below deck. Garmin recognised this role for the quatix early on as Mobile subsidiary display for the NMEA-2000 system created.

Bundles for the wind turbine

As well as the standalone unit, Garmin offers several bundles. Depending on the version, these include a wired or wireless gWind sensor, as well as depth, speed and temperature sensors. The Wireless Sail bundles are designed specifically to reduce the effort involved in mast installation: for masts up to 15 metres in length, there is no need to run cables to the wind sensor.

According to Garmin, the DST820 Smart Transducer measures depth, speed and water temperature. It also provides data on heeling, pitching and rolling. The GDT-43 and GST-43 transducers, on the other hand, are designed for boat owners who wish to continue using existing 43-millimetre hull cut-outs.

The GMI 40 is expected to cost around 700 euros as a standalone unit, whilst the sets including transmitters cost between 1,200 and 2,100 euros, depending on the configuration.

Technical Specifications

Book recommendations

Stress-free navigation explains the principles underpinning many of the displays at the helm: course, speed, depth, GPS position and how these fit into trip planning. The guide combines traditional navigation with electronic aids and helps readers not only to read instrument readings but also to interpret them correctly within a nautical context. This is particularly helpful when a new display is intended to make the data on board more visible.

Theory and Practice of Vehicle Electrical Systems covers the electrical infrastructure behind the display: power supply, distribution, cabling, troubleshooting and the integration of devices such as loggers, depth sounders and plotters. Featuring numerous drawings, photographs and tables, the book is aimed at boat owners who wish to plan their instrument system themselves during a refit or to oversee the installation with expert knowledge.

Would a separate multifunction display be useful at your helm, or are the wind, depth and speed readings on the chartplotter sufficient for you? Please let us know which data you’d like to keep an eye on at all times whilst sailing.