Navigation: Navimetrix - weather routing app with AI support and a huge range of functions

Navimetrix is the brainchild of French developers Henri Laurent (known from SailGrib) and Olivier Bouyssou (known from Weather4D). Both have pooled their many years of experience and founded the joint company SOFT4SAIL. The new app combines the findings from both predecessors and significantly expands the range of functions. Unlike most of its competitors, Navimetrix automatically synchronises all routings, waypoints and settings between all devices via the cloud - regardless of the operating system.

Remarkable history

The Navimetrix routing engine was originally developed for Virtual Regatta - a popular online sailing game with millions of users worldwide. More than 100,000 users accessed the routing every day. The developers used the game as a huge test laboratory for their software. If the infrastructure can cope with this load, it should also work smoothly with the significantly smaller number of real sailors. In practice, the app works stably and very quickly on iOS and Android mobile devices as well as on Mac and Windows.

Two-part system: separate routing and nautical charts

Navimetrix is clearly divided into two parts: The app itself handles all the weather routing based on GRIB weather data, which must be downloaded separately. The nautical charts, however, come from the external provider GeoGarage, which requires a separate subscription. For Germany, the nautical chart subscription with BSH data costs 25 euros per year; other regions are billed separately. However, the price list is not always transparent - Denmark, for example, is displayed as "not available", but still worked in our app.

The nautical charts are raster charts from official providers such as the BSH for Germany. They look like real paper charts on the screen. One disadvantage: the transition between countries is not seamless. Even after downloading, the appropriate detailed chart must be selected for each sea area. Although the map sets overlap - the Danish map also shows German waters - the level of detail varies greatly. Harbour plans and fine details are only available in the respective country map. This is much more complicated than with Navionics, Orca or C-Map, where everything works seamlessly.

For offline use, maps can be downloaded in full resolution (coastal areas) or reduced resolution (ocean passages) to save memory and download volume.

GRIB data: Easy download, many models

The real strength of Navimetrix lies in weather routing. To do this, GRIB weather data must first be downloaded. The dialogue is relatively intuitive: select the sea area, specify the data type (atmospheric, tidal, swell, ensemble), select the resolution (global or regional high-resolution).

The model selection is particularly impressive. In the free version, only a simple GFS model with a maximum forecast period of five days is available. Premium access (Navimetrix subscription: 79.99 euros per year) gives you access to six high-resolution regional weather models:

Arpège Europe 0.1° (11 kilometres)

• Regional model of Météo-France
• Coverage: Europe to the Canary Islands
• Forecast: up to four days
• Ideal for: English Channel, Atlantic, Mediterranean - reliably records large-scale European weather systems

Arome 0.025° (three kilometres)

• High-resolution model from Météo-France
• Forecast: up to 48 hours
• Ideal for: Coastal navigation in France - captures local effects such as sea winds, summer thunderstorms and terrain-related winds

Arome HD 0.01° (one kilometre)

• High-resolution version of the Arome model
• Forecast: up to 24 hours
• Ideal for: Regatta sailing and coastal sailing - shows the smallest wind changes on capes, bays and coastal terrain. Caution: Can sometimes react somewhat "nervously"

ICON Europe 0.07° (eight kilometres)

• Regional model of the German Weather Service (DWD)
• Forecast: up to five days
• Ideal for: English Channel, North Sea, Western Mediterranean and neighbouring Atlantic - considered the best model for the Mediterranean and a good complement to the French models

ICON D2 0.02° (two kilometres)

• High-resolution version of the ICON model
• Focus: Germany and neighbouring countries
• Forecast: up to 48 hours
• Ideal for: North Sea and Baltic Sea, where local effects (coastal winds, thunderstorms) are important

UKV 0.05° (six kilometres)

• Regional model of the UK Met Office
• Coverage: United Kingdom and neighbouring territories
• Forecast: up to 48 hours
• Ideal for: Sailing around the British Isles, the English Channel and the Celtic Sea

A brief description of each model can be called up directly in the app. You can individually select the time step (e.g. hourly), the forecast period and the desired parameters (wind, air pressure, temperature, cloud cover, precipitation). The model selection is therefore much more extensive than with most competitor apps.

Routing: Professional and fast

Routing can start after the GRIB download. You create at least one start and one end waypoint. In theory, the app automatically calculates the entire route for up to 15 days in advance. This works very well for long offshore legs. In narrow areas, it has proven useful to specify a rough route with critical waypoints - otherwise the system may navigate over shallows or ignore bridge crossings.

The routing requires boat data as a basis. Navimetrix offers a large database of polar diagrams, and you can also upload your own polar data or use an integrated iPolar tool to create a simple polar diagram from a few key data points. This is not as precise as a VPP-generated polar diagram, but it is better than nothing.

Routing is not only intended for regatta sailors. You can set the engine to be used in winds below a certain speed (e.g. six knots) and the cruising speed to be used. The polar power can also be reduced for night sections or the routing can be organised differently. A special feature is the option to turn. This allows you to instruct the software to sit out short-term periods of strong winds that exceed the selected wind limit and continue sailing after the front has passed. Conventional routing systems usually try to avoid the strong wind in such conditions and generate large detours.

Isochronous and interactive routing - like Expedition

A function that is otherwise only offered by professional routing programmes such as Expedition (over 1,000 euros): Navimetrix displays isochrones - lines of the same time that show all possible positions after an hour's journey, for example.

The big advantage: you can simply move the cursor over the map and a route is immediately displayed showing you how to get to this point. If you click on the point, a new route is calculated from there in just a few seconds. This is extremely practical if you realise on the way: "I want to pass the other side of the island."

Even more impressive: you can have various alternative routes shown in parallel on the display and have the "boats" travelled by animation. This allows you to quickly recognise which route you would be on when and where, and which route is faster in which section. Along each route, the wind, boat speed and any motor utilisation are displayed. A test route from Kiel to Oslo shows just how quickly the software works: the approximately 300 nautical mile route was calculated in just under eleven seconds. Orca needs around three times as long for the same calculation.

Zones of Interest - ingenious workaround

The "Zones of Interest" are a truly unique feature. You can simply use the mouse (or your finger) to click on restricted areas on the chart. The routing then automatically avoids these areas. This is a perfect workaround if nautical chart data is incomplete and traffic separation schemes, wind farms or firing ranges have not been digitised in such a way that they are recognised by the routing software. This is an annoying problem with other programmes - Navimetrix solves it elegantly with just a few clicks.

AI sailing instructions

Absolutely new and not yet available in any other weather routing app: Navimetrix uses AI to create an automatic briefing for every calculated route. You receive a detailed summary with:

• Description of the weather conditions
• Route
• Detailed risk analysis: What weather changes are to be expected? Where do gusts threaten? Are there any problems with tidal currents or wind against current? What are the sea conditions like?
• Recommendations on which weather maps you should also download

Routing evaluation and statistics

Once routings have been created, they remain saved and can be analysed in detail at a later date:

• Courses, distances and weather conditions per section
• Statistics: Percentage distribution according to wind angles (e.g. "35 % downwind with 35° AWA, 20 % downwind with 150° AWA")
• Input overview: Which weather model, which time and which polar were used?

This is particularly helpful if you want to compare several routings with different parameters. A direct connection to the chart plotter is not possible; the routes must be exported as a GPX file and loaded manually into the plotter.

AIS - extremely powerful

Navimetrix displays AIS data (Internet AIS or own receiver on board) with advance vectors on the nautical chart. However, the app goes much further than other programmes: AIS targets can be sorted with extensive filters in a list view:

• Distance, CPA (minimum approach), time to CPA
• Name, MMSI, risk
• Travel over ground (five minutes or 20 minutes averaged)

There is also a free search field that can be used to search through the entire AIS stream. This also allows you to search backwards, as with MarineTraffic: search for a ship's name, click on it and the map will automatically zoom to the target. Another feature: AIS targets can be summarised in groups (e.g. regatta participants) in order to display only these ships and compare their speed and courses.

Tides, live weather data, overlays

Not only the forecasts of the GRIB data can be used for tidal areas. In Germany, all BSH tide gauges can also be called up directly. Live weather stations on land (e.g. from airports), satellite measurements and ship measurements are also displayed on the nautical chart - wind speed and air temperature can be obtained by clicking on the station.

The map backgrounds available include not only nautical charts, but also OpenStreetMap, Bing satellite images and real-time satellite data (weather). You can choose between global coverage or high-resolution regional images and see live cloud cover. No other sat nav app offers this yet.

The weather display is highly customisable: you can choose between mean wind, gusts, gust difference, air pressure, temperature, precipitation, overcast, lightning and rain radar. The wind field can be displayed as classic wind arrows or, as with Windy, as a modern particle animation.

Cloud sync - cross-platform

A major advantage: all routing data is saved on the server. If you log in on another device with the same user data, all routings, danger zones and settings are automatically available. This works between Android, iOS, macOS and Windows 11. Linux and Windows on Arm are planned. We have tested the software on iPhone, iPad, MacBook and a Windows 11 computer.

iPhone and iPad: The app runs smoothly and stably. On the iPhone, however, the display is small and delicate functions such as setting "Zones of Interest" quickly become fiddly (sausage finger problem). The iPad is a good compromise: sufficiently large display, stable performance, touch operation works well.

MacBook Air: There are advantages and disadvantages here. The big advantage is the mouse operation: Filigree functions such as setting zones or detailed views are much more precise and convenient with the mouse. However, the adaptation to macOS is not yet optimal. The window management is unintuitive: where a "Cancel" button closes a dialogue on the iPad, a new window opens on the Mac, which you have to close separately - this looks like a hang-up, but is just an operating peculiarity.

Windows 11: Installation runs smoothly and downloading the basic data is also done quickly. The app runs stably and is very easy to use thanks to the mouse. The window management is even slightly better than on the Mac, as opening sub-windows can be clearly recognised as such. This ensures less confusion when switching from the mobile device to the desktop or notebook version for the first time.

CONCLUSION

Navimetrix is an impressively powerful weather routing app with functions that are otherwise only offered by professional software costing over €1,000. The isochrone display, interactive routing, AI sailing instructions and extremely detailed AIS integration are unique selling points. The cross-platform cloud synchronisation works very well.

The nautical chart integration is somewhat cumbersome, as it does not work seamlessly at national borders and a separate GeoGarage subscription is required. The macOS version has stability problems, and the Windows version requires powerful hardware.

Navimetrix costs 79.99 euros per year, GeoGarage from 25 euros per region. This is significantly cheaper than professional software and comparable to other premium apps with much simpler routing. This makes Navimetrix interesting not only for regatta sailors who want to use professional weather routing without spending €1,000+ on Expedition, but also for ambitious cruising sailors.

Functions and prices

• Platforms: Android, iOS, macOS, Windows 11 (Linux and Windows on ARM in planning)
• Price: €79.99/year (Premium with all weather models)
• Free version: Limited (only one weather model)
• Cloud sync: in combination with a premium account
• Routing: Isochrone, interactive routing, weather routing
• AI sailing instructions: Yes (unique worldwide)
• GRIB models (Premium): Arpège, Arome (1 km), ICON Europe (8 km), ICON D2 (2 km)
• Forecast period: Depending on the weather model up to 15 days
• AIS: Internet AIS or own receiver, groups, filters, reverse search
• Display of NMEA data
• Polar database: Yes, large selection + own upload + generator
• Motor routing: Yes (cruising with little wind)
• Night mode: Yes (reduced performance)
• Zones of interest: Yes (restricted areas can be marked)
• Live weather data: Airports, ships, BSH levels
• Overlays: nautical charts, OpenStreetMap, Bing satellite images, weather satellite data

GeoGarage (nautical charts, separate subscription):

• Provider: External (not Navimetrix)
• Map type: Raster maps (official providers such as BSH)
• Price Germany: 25 €/year
• Offline download: Yes (full or reduced resolution)
• Seamless transitions: No (country-specific, manual change required)
• Depth of detail: Only high in the respective country map (harbour plans etc.)

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