The NavimetriX interface has been designed to be clear, intuitive, and quick to use, whether on a computer, tablet, or smartphone. Here is a complete description, section by section:

- Top right

• • ⚙ Settings icon: opens the settings panel
  • 👤Account icon: allows you to log in to your NavimetriX account, create an account, or reset your password.
  • ? Help icon : Open the application's website, in the Frequently Asked Questions or FAQs tab.

- Top left

☰ Hamburger menu: provides access to the application's main lists:

• • GRIBs files
  • POIs Points of Interest
  • ZOIs Zones to avoid, i.e. Traffic Separation Schemes
  • Routes
  • Routings
  • AIS targets

- Bottom left

• • Map scale
  • GRIB file loaded, in example : GFS 0.25° 20251007 00Z +384
    • • GFS model
      • 0.25° grid, approximately 26 km
      • published by NOAA on October 7, 2025
      • Calculated at midnight UTC, we refer to the 0-hour run or 00Z.
      • containing 384 hours from the 00Z run. If you see +36, this indicates that the first 36 hours of this GRIB file are from the 00Z run, while the following hours are from the previous run, which was the 18Z run on October 6. This gives you access to the latest data from the run without having to wait for the entire run to be calculated. For the GFS, this saves about 3 hours.

- Below: the Timeline

• • Displays all hours covered by the currently loaded GRIB file.
  • Each white dot on the time bar corresponds to a time step in the GRIB file.
  • The time displayed just above indicates the current position of the Timeline.
  • If you click/tap on this time, the Timeline will jump to “now” and the seconds will scroll by (letting you know that you are at the current time)
  • You can:
    • • Slide the Timeline with your finger or mouse,
      • Click/tap on a location to move directly to a specific time.

• • The data in the GRIB file displayed is then that for the selected time.
  • If a routing is displayed, the boat moves at the selected time along its trajectory.
  • At the bottom right, the coordinates of the target in the center of the screen are displayed.

- Bottom right: the three orange circular buttons

• • Action Button (+)
    • • Download a GRIB file,
      • Add a POI,
      • Create a ZOI
      • Create a route,
      • Calculate a routing.
      • Add a new measure

• • Boat Button
    • • Centers the map on the boat's position.
      • Long press : automatically centers and zooms in for a closer view—ideal for navigation.

• • Layers button
    • • Chart section :Allows you to choose the type of chart displayed:
        • • OpenStreetMap (default)
          • Bing Satellite
          • Realtime Satellites images
          • Geogarage: Nautical charts, if available.
    • • GRIB Display section
        • • Allows you to choose which weather parameters to display:
            • • Background color,
              • Wind barbs,
              • Isobars
              • Weather maps
              • Current atlases (SHOM)
              • Additional data depending on the loaded model.
          • Target (dropdown menu): Screen center (default), disabled, GPS location, POI.
    • • Display Section
        • • Allows you to enable or disable the display of :
            • • Tides
              • Weather stations
              • POIs,
              • AIS targets
              • Lightning, Thunders
              • Rain Radar
              • Isochrones
              • Laylines
              • Lat/Lon grid
              • Auto measure

- On the map

• • Target in the center of the screen.
    • • Orange if at sea
      • Blue if on the ground The target's coordinates are displayed at the bottom right.

• • Data from the GRIB file at the target at the time of the time bar

• • Tide icons around the world
    • • Red : ebb tide.
      • Green : rising tide. Clicking on an icon opens the tide details with the times and heights calculated directly in the application.

• • No-go zones
    • • red polygons, such as TSS (Traffic Separation Schemes) or offshore wind farm areas

• • Points of Interest (POIs)
    • • in orange

You will find a short tutorial on the basic functions of NavimetriX by following Get Started.

Before writing to us, please check the FAQs — you’ll probably find the answer to your question 😉.
There’s no need to browse through all the FAQs one by one: you can search within the FAQs, so don’t hesitate to use the search bar!

• If you are using the app, please use the “Contact us” menu option in Settings. An email will automatically be prepared with some technical data, and a "log" file in attachment (*), that will help us respond to you. Please be specific in your questions and don’t hesitate to attach screenshots.

• Otherwise, please use the contact form on this website.

(*) For Windows and macOS, if the log file isn't attached to the email, you can add it manually; it can be found here:

• Windows:

C:\Users[your username]\AppData\Local\Soft4Sail\NavimetriX\logs\navimetrix.log

• macOS:

~/Users/[your username]/Library/Containers/navimetrix/Data/Library/Application Support/Soft4Sail/NavimetriX/logs/navimetrix.log

How to synchronise?

In order for NavimetriX to be synchronised across two or more devices, you must:

1. Have subscribed to the Premium option and created a NavimetriX account
2. Have devices connected to the Internet (Wi-Fi, cellular or satellite).
3. Be logged into the same NavimetriX account on all devices

Which items are synchronised and which are not?

Most settings are synchronised, with a few exceptions, namely:

Synchronised

• All application settings, except:
  • The language used
  • The display size percentage
  • The instrument configuration (which must be fitted to screen sizes)
  • Internal or NMEA GPS source (GPS & NMEA)
• With no exception
  • POIs, routes, routings, routing tables, statistics, AI briefing, input data
  • Screen display of charts, GRIBs, POIs, tides, AIS targets, routing isochrones

Partially synchronised

• GRIBs files

Downloaded GRIB files appear in the GRIB list on all devices. When a GRIB is downloaded or updated on a device, it is followed by a dimmed refresh icon. If a new run is available for that GRIB, this icon is activated.

On other device(s), the list of downloaded GRIBs is displayed but followed by an activated download icon. The contents of the GRIBs must then be downloaded manually.

• Geogarage charts

The Geogarage account is synchronised across all devices.
Geogarage charting is not synchronised: charts must be downloaded to each device.

📘 This glossary brings together the main terms used in the Navimetrix application and its FAQs. It helps users better understand concepts related to navigation, routing, and marine weather.

Course Over Ground (COG)

The actual direction of the boat’s movement over the seabed, expressed in degrees relative to true north. It differs from the compass heading when there is drift caused by wind or current.

Speed Over Ground (SOG)

The boat’s actual speed relative to the ground (not the water). Calculated by GPS, it includes the effect of currents.

Heading (HDG)

The direction in which the boat’s bow is pointing, measured relative to true or magnetic north.

True Wind Angle (TWA)

The angle between the boat’s axis and the true wind direction. It is calculated from the apparent wind and the boat’s speed.

True Wind Speed (TWS)

The wind speed derived from the apparent wind and the boat’s speed. It represents the actual wind strength on the sea surface.

Apparent Wind Angle (AWA)

The wind angle felt on board, influenced by the boat’s motion. Measured relative to the boat’s centerline.

Apparent Wind Speed (AWS)

The wind speed felt on the boat, resulting from the combination of the true wind and the boat’s speed.

Velocity Made Good (VMG)

The useful component of the boat’s speed, indicating the effective progress toward the destination or upwind.

Closest Point of Approach (CPA)

The point at which two vessels will be at their minimum distance from each other, based on their current courses and speeds.

Time to CPA (TCPA)

The time remaining before reaching the CPA, used for collision avoidance and AIS alarms.

Bearing

The angle between north and the direction of an observed object from the boat. Used to determine the relative position of a target or coastline.

Depth

The water depth below the keel, measured by an echo sounder. A key parameter for safe navigation.

Waypoint (POI / Waypoint)

A geographic point used to define a route or a key position. In Navimetrix, POIs represent these waypoints.

GRIB File (Gridded Binary)

A standard file format containing numerical weather forecasts (wind, waves, pressure, temperature, etc.).

Isochrone

A curve connecting all possible boat positions at a given time according to the predicted weather conditions.

Routing

The calculation of an optimal route considering wind, waves, currents, and the boat’s performance.

Polar

A performance curve showing the boat’s speed as a function of wind angle and wind strength. It forms the basis for the routing engine.

Estimated Time of Arrival (ETA)

The predicted time of arrival at the destination, calculated from the remaining distance and the average speed.

Sea State

A description of the waves and swell (height, direction, period). Used to assess routing comfort and safety.

Swell

A regular train of waves formed by distant winds. It differs from the wind sea, which is generated locally.

Significant Wave Height

The average height of the highest one-third of waves, the main indicator of overall sea conditions.

Currents

Water movements caused by tides or ocean circulation. They affect the boat’s speed and trajectory.

Tide

Variation in sea level caused by the gravitational attraction of the Moon and the Sun. It influences depth and coastal currents.

• Requirements: You must have subscribed to the Premium option and created an account on the device used to take out the subscription.
• Press “👤 My Account” at the top right.
• Go to the Reset tab in the Authentication menu.
• Enter the email address of your NavimetriX account and press Request Reset.
• An email is sent to your inbox — press Dismiss on the information window.
• Enter the reset code and the new password.
• Press the Reset button.

Q4 2025

• Distance measurement - ✓
• Edit zones (restricted, slow, info) - ✓
• Isobar redesign - ✓
• Display of all weather parameters - ✓
• Route plan - ✓
• Data along the routing - ✓
• Meteogram in grid format - ✓
• Alarms - ✓
• Multi-GRIB routings - ✓
• “In situ” data - ✓
• NKE interface - ✓
• Autopilot control interface - ✓
• Laylines - ✓
• Demo mode - ✓

Q1 2026

• Linux - ✓
• Multi-GRIB routing - ✓
• Route tracking - ✓
• Race tracking - ✓
• AIS over Internet - ✓
• NMEA over USB - ✓
• Import third party GRIB files
• SHOM currents atlases - ✓
• Automatic Routing Playback (Play button) - ✓
• Full screen mode

Q2 2026

• CMap charts
• Dual-screen mode
• Polar editor
• Satellite images - ✓
• Isobaric charts - ✓
• Rain Radar - ✓
• Avurnav
• Ensemble routing - ✓
• Safe Mode
• Automatic local backup

Q3 / Q4 2026

• ENC charts
• Local network synchronization
• Navigator
• Wave modeling
• Navigation sharing

To create a NavimetriX account, you must first subscribe to the Premium subscription for the 7-day trial period.

Once you have subscribed, the “Shopping Cart” icon will disappear from the screen.

• Tap “My Account” in the top right corner, or the icon opposite (for smartphones).
• Select the Sign Up tab from the Authentication menu.
• Enter an email address and password.
• Tap the orange Request Code button.
• Enter the code you received, then tap the Sign Up button.
• Select the Log In tab in the Authentication menu.
• Enter the credentials you have created for your NavimetriX account and press the orange Log In button.

• Select the Log In tab from the Authentication menu.
• Enter the credentials you created and press Log In button.
• "My Account” button has been replaced by “Logout.”

💻 Desktop:

• macOS: Version 13 (macOS Ventura), released on October 24, 2022, and all later versions.
  (x86_64, x86_64h, and arm64).
  
• Windows: Version 10 (build 1809 - 10.0.17763) or later, Windows 11 - x86_64 and ARM64, released in October 2018.

📱 Mobile:

• Android: Version 9 (API 28) to 15 (API 35) - arm64-v8a, x86_64, x86, and armeabi-v7a. Android 9 was released in August 2018.
• iOS: Version 16 or later (including iOS 18) - armv8, arm64. iOS 16 was released in September 2022.

⚠️ Important:

These operating system versions are prerequisites for running NavimetriX, as they define compatibility with our development framework.
However, they do not guarantee that the application will be fully compatible with your device. Other factors such as insufficient RAM (*) or a low-performance graphics processor may also affect performance and compatibility.

———

(*) Regarding Windows 11, the system uses 6 GB on a PC fitted with 8 GB of RAM and more than 10 GB on a machine with 16 GB.

• Scroll down to the bottom of this page
• Click the “Get it from Microsoft” button
• Download the installation file
• Run the installation file

⚠️ If you receive a warning from your antivirus, it is most likely a false positive. The NavimetrixSetup x.x.xx.exe file is officially signed with an EV (Extended Validation) code signing certificate issued by SSL.com, on behalf of SOFT4SAIL (France).
You can check on VirusTotal that our .exe file is clean and recognized as safe by major antivirus programs.

The blocking message displayed by Windows corresponds to the “SmartScreen” protection mechanism, which can be temporarily triggered on recent or little-used applications, even when they are correctly signed. You can therefore safely authorize the application to run:

Either in the window that appears:

• Click on the “Learn more” option, then “Run anyway.”

Or by marking the file as safe:

• Right-click on NavimatrixSetup x.x.xx.exe.
• Select “Properties.”
• At the bottom of the “General” tab, check “Unblock.”
• Click “Apply” then “OK.”
• Restart the installation.

Resolving an issue on a Windows PC can be complex, given the wide variety of possible configurations. Here are some basic steps to check:

1. Check the app version
   • Make sure you have the latest version of the application.
     The version number is displayed at the top right under the cogwheel icon. It will appear in red if your version is outdated. If you don’t see it, your version is very old. To update your app, follow this link and click the “Get it from Microsoft” button.
     
2. Check your Windows version
   • Your system must be Version 10 (build 1809 – 10.0.17763) or later, 64-bit (x86_64). See the prerequisites in the FAQ section of our website for more details.
     
3. Try another network
   • If you are connected to your home Wi-Fi, try using mobile data sharing (hotspot), or vice versa.
   • If you are on a corporate network, make sure you are not behind a firewall that could block certain data (such as coastlines or weather data) from loading.
   • If you use a VPN, disable it.
     
4. Restart your PC
   
5. Check our Facebook group
   • Visit the Navimetrix Users Facebook Group to see if other users are experiencing the same issue.

If these steps do not solve the problem, your PC may not be compatible due to insufficient RAM or a graphics card that does not meet the app’s requirements.

To uninstall the application:

• Close NavimetriX
• Uninstall the application from the Windows menu “Add or Remove Programs.”

The application will be uninstalled, and all folders where it stores data as well as its registry keys will be removed.

• Uninstall the application by moving it to the Trash
• Open Finder
  - Go to the directory /Users/[user]
  - Show hidden files and folders in this directory by pressing "Command" + "Shift" + "." (period) simultaneously.
  
  - Delete the following directory:
  /Users/[user]/Library/Containers/eSail4VR
  Replace [user] with your Mac username.

You can also use the CleanMyMac application.

In the Settings panel, the first section covers the basic configuration options:

• Language: French, English, German, Spanish
• Theme: light or dark user interface
• Time zone: local (based on your device) or UTC (Universal Time)
• Display scale: allows you to decrease or increase the size of the objects on the map.
• Units: choose according to your preferred measurement system.
• My boat: all parameters related to your vessel — polar, name, type, MMSI, etc.

If you get an error message saying “Unable to run a file from the temporary folder. Aborting installation. Error 4551: An application control policy has blocked this file” with Windows 11:

This error is caused by Smart App Control, a Windows 11 security feature that sometimes blocks the installation of new software.

To resolve the issue, you must:

1. Go to Settings → Privacy and Security → Windows Security → App and browser control.
2. Click Smart App Control and disable it.
3. Restart the installation.

You can reactivate Smart App Control after installation.

If there is no Wi-Fi or USB connection to the onboard instruments, you can use a Bluetooth GPS device such as the GNS3000 from GNS Electronics. The procedure is as follows:

1. Pairing the device:
   • Put your GPS receiver into “pairing” mode (refer to the user manual for specific instructions; this usually involves pressing and holding a button).
   • In Windows 11, go to Settings > Bluetooth & devices > Add a device.
   • Select Bluetooth, choose your GPS receiver from the list, and complete the pairing process.
2. Checking in Device Manager:
   • Once connected, Windows usually installs the driver automatically.
   • Right-click the Start button > Device Manager.
   • Expand the Ports (COM & LPT) section. Your GPS should appear as a USB or Bluetooth serial port (e.g., “Standard Serial over Bluetooth link” with a COM port number, such as COM3). Note this port number.
3. Using it with NavimetriX:
   • Navigation applications can read NMEA data from the COM port identified in the previous step.

You should see your location data appear. If your GPS isn't detected, make sure the manufacturer-specific drivers (e.g., Garmin, Globalsat, GNS) are installed for your Windows version.

With a Premium subscription, you’ll enjoy the full potential of the application.

In addition to all the features of the free version:

• Synchronization across all your devices with a NavimetriX account: create a route on your phone, and it is instantly available on your PC
• Wide selection of weather models
• Wave and current forecasts
• Forecasts up to 15 days ahead for global models such as the U.S. GFS and the European IFS
• Routing up to 15 days
• Weather briefing generated by our AI
• Navigation mode
• Connection to onboard GPS and NMEA data
• AIS target processing
• And much more...

You’ll benefit from a 7-day free trial period, so don’t hesitate to give it a try — we’re confident you’ll be convinced.

The Premium subscription is annual and renews automatically.
The price depends on the region where you subscribe.
For example, it is:

• 70 GBP in the UK
• $80 in the US
• €80 per year in mainland France.

Please note that the subscription does not include nautical charts. To navigate with marine charts, you need to have a subscription on the Geogarage platform.

At the moment, you cannot subscribe directly from a Windows PC. To get a subscription, please use your phone (or tablet) via the App Store for iOS or macOS, or the Play Store for Android.
This subscription will then be valid on all your devices, including your PC.

When renewing a subscription or at the end of the trial period, in order to update our database with the information provided by the App Store, you must launch the application on the device that took out the subscription.

Important: On your PC or any device where you did not take your subscription, make sure to login to your NavimetriX account to see your subscription

• Requirements: You must have subscribed to the Premium option and created an account on the device used to take out the subscription.
• Press “👤 My Account” at the top right.
• Go to the Reset tab in the Authentication menu.
• Enter the email address of your NavimetriX account and press Request Reset.
• An email is sent to your inbox — press Dismiss on the information window.
• Enter the reset code and the new password.
• Press the Reset button.

• Cancel your subscription on the Apple Store (iOS/iPadOS):

Cancellation is done through your Apple account.
To turn off an automatically renewing subscription on an Apple device (iOS/iPadOS):
Settings > Your Account > Subscriptions > Select the subscription > Cancel Subscription

• Cancel your subscription on the Apple Store (macOS):

To cancel a subscription on a Mac, follow this link.

Note: Do not cancel before the end of the 7-day free trial if you wish to keep Premium access. However, if you do not want to subscribe, you must cancel before the end of the 7th day to avoid being charged.

• Cancel your subscription on the Google Play Store (Android):

Cancellation is done through your Play Store account.
To turn off an automatically renewing subscription on an Android device:
Follow the instructions on this page.

Note: Do not cancel before the end of the 7-day free trial if you wish to keep Premium access. However, if you do not want to subscribe, you must cancel before the end of the 7th day to avoid being charged.

To create a NavimetriX account, you must first subscribe to the Premium subscription for the 7-day trial period.

Once you have subscribed, the “Shopping Cart” icon will disappear from the screen.

• Tap “My Account” in the top right corner, or the icon opposite (for smartphones).
• Select the Sign Up tab from the Authentication menu.
• Enter an email address and password.
• Tap the orange Request Code button.
• Enter the code you received, then tap the Sign Up button.
• Select the Log In tab in the Authentication menu.
• Enter the credentials you have created for your NavimetriX account and press the orange Log In button.

• Select the Log In tab from the Authentication menu.
• Enter the credentials you created and press Log In button.
• "My Account” button has been replaced by “Logout.”

The NavimetriX interface has been designed to be clear, intuitive, and quick to use, whether on a computer, tablet, or smartphone. Here is a complete description, section by section:

- Top right

• • ⚙ Settings icon: opens the settings panel
  • 👤Account icon: allows you to log in to your NavimetriX account, create an account, or reset your password.
  • ? Help icon : Open the application's website, in the Frequently Asked Questions or FAQs tab.

- Top left

☰ Hamburger menu: provides access to the application's main lists:

• • GRIBs files
  • POIs Points of Interest
  • ZOIs Zones to avoid, i.e. Traffic Separation Schemes
  • Routes
  • Routings
  • AIS targets

- Bottom left

• • Map scale
  • GRIB file loaded, in example : GFS 0.25° 20251007 00Z +384
    • • GFS model
      • 0.25° grid, approximately 26 km
      • published by NOAA on October 7, 2025
      • Calculated at midnight UTC, we refer to the 0-hour run or 00Z.
      • containing 384 hours from the 00Z run. If you see +36, this indicates that the first 36 hours of this GRIB file are from the 00Z run, while the following hours are from the previous run, which was the 18Z run on October 6. This gives you access to the latest data from the run without having to wait for the entire run to be calculated. For the GFS, this saves about 3 hours.

- Below: the Timeline

• • Displays all hours covered by the currently loaded GRIB file.
  • Each white dot on the time bar corresponds to a time step in the GRIB file.
  • The time displayed just above indicates the current position of the Timeline.
  • If you click/tap on this time, the Timeline will jump to “now” and the seconds will scroll by (letting you know that you are at the current time)
  • You can:
    • • Slide the Timeline with your finger or mouse,
      • Click/tap on a location to move directly to a specific time.

• • The data in the GRIB file displayed is then that for the selected time.
  • If a routing is displayed, the boat moves at the selected time along its trajectory.
  • At the bottom right, the coordinates of the target in the center of the screen are displayed.

- Bottom right: the three orange circular buttons

• • Action Button (+)
    • • Download a GRIB file,
      • Add a POI,
      • Create a ZOI
      • Create a route,
      • Calculate a routing.
      • Add a new measure

• • Boat Button
    • • Centers the map on the boat's position.
      • Long press : automatically centers and zooms in for a closer view—ideal for navigation.

• • Layers button
    • • Chart section :Allows you to choose the type of chart displayed:
        • • OpenStreetMap (default)
          • Bing Satellite
          • Realtime Satellites images
          • Geogarage: Nautical charts, if available.
    • • GRIB Display section
        • • Allows you to choose which weather parameters to display:
            • • Background color,
              • Wind barbs,
              • Isobars
              • Weather maps
              • Current atlases (SHOM)
              • Additional data depending on the loaded model.
          • Target (dropdown menu): Screen center (default), disabled, GPS location, POI.
    • • Display Section
        • • Allows you to enable or disable the display of :
            • • Tides
              • Weather stations
              • POIs,
              • AIS targets
              • Lightning, Thunders
              • Rain Radar
              • Isochrones
              • Laylines
              • Lat/Lon grid
              • Auto measure

- On the map

• • Target in the center of the screen.
    • • Orange if at sea
      • Blue if on the ground The target's coordinates are displayed at the bottom right.

• • Data from the GRIB file at the target at the time of the time bar

• • Tide icons around the world
    • • Red : ebb tide.
      • Green : rising tide. Clicking on an icon opens the tide details with the times and heights calculated directly in the application.

• • No-go zones
    • • red polygons, such as TSS (Traffic Separation Schemes) or offshore wind farm areas

• • Points of Interest (POIs)
    • • in orange

How to synchronise?

In order for NavimetriX to be synchronised across two or more devices, you must:

1. Have subscribed to the Premium option and created a NavimetriX account
2. Have devices connected to the Internet (Wi-Fi, cellular or satellite).
3. Be logged into the same NavimetriX account on all devices

Which items are synchronised and which are not?

Most settings are synchronised, with a few exceptions, namely:

Synchronised

• All application settings, except:
  • The language used
  • The display size percentage
  • The instrument configuration (which must be fitted to screen sizes)
  • Internal or NMEA GPS source (GPS & NMEA)
• With no exception
  • POIs, routes, routings, routing tables, statistics, AI briefing, input data
  • Screen display of charts, GRIBs, POIs, tides, AIS targets, routing isochrones

Partially synchronised

• GRIBs files

Downloaded GRIB files appear in the GRIB list on all devices. When a GRIB is downloaded or updated on a device, it is followed by a dimmed refresh icon. If a new run is available for that GRIB, this icon is activated.

On other device(s), the list of downloaded GRIBs is displayed but followed by an activated download icon. The contents of the GRIBs must then be downloaded manually.

• Geogarage charts

The Geogarage account is synchronised across all devices.
Geogarage charting is not synchronised: charts must be downloaded to each device.

In the Settings panel, the first section covers the basic configuration options:

• Language: French, English, German, Spanish
• Theme: light or dark user interface
• Time zone: local (based on your device) or UTC (Universal Time)
• Display scale: allows you to decrease or increase the size of the objects on the map.
• Units: choose according to your preferred measurement system.
• My boat: all parameters related to your vessel — polar, name, type, MMSI, etc.

Some settings are essential — both for safety and for the proper functioning of the application.

• Disable the device unlock code

You and your crew members must be able to access the navigation app instantly, whatever the situation. At sea, a code is useless — even dangerous if you are unable to handle navigation yourself: your crew must be able to take over quickly.

• Disable automatic sleep mode
  • On iPad / iPhone: Settings > Display & Brightness > Auto-Lock = “Never”.
  • On Android devices: Settings > Display > Screen timeout = from 0 to 30 minutes depending on the brand and model — unfortunately, “Never” is rarely available. Set it to the maximum possible time.

Unexpected sleep mode during a critical navigation moment (e.g., nighttime landfall in the rain in an unknown area) can be dangerous if you cannot instantly relaunch the app (e.g., wet fingers or touchscreen not responding). You should manually activate or deactivate your device depending on the situation.

In addition, sleep mode interrupts track recording.

• Disable spell checking
  • On iPad / iPhone: Settings > General > Keyboard > Auto-Correction = disable.
  • On Android devices: Settings > General Management > Samsung Keyboard Settings > Auto spell check = disable.

This prevents wasting time when entering text in the app, such as route names, POIs, etc.

Regarding onboard computers, PC or Mac, the same recommendations apply. Adjust the settings according to the operating system and version used.

This setting allows you to enlarge or reduce the size of all elements displayed on the map (up to 140%, for example). Very useful on board if you want to use the app without wearing your glasses.
Note that the menu font size remains unchanged.

Your boat’s polar determines all routing calculations. It represents your boat’s performance depending on wind speed and angle.
The application supports files in the .pol format (also used by Weather4D, SailGrib, Adrena, and others).

To choose your boat’s polar from the library:

1. Go to the “My Boat” tab.
2. Click on the selected Polar.
3. A dialog opens with three tabs: Library, Imported, or iPolar.
4. In the “Library” tab, you’ll find a list of 495 polars for various well-known boats.

Most of these polars come from naval architects or ORC certificates.
To find your polar, you can:

• Scroll through the list.
• Use the search function — for example, type “3600” to find the polar for the Sun Fast 3600.

Once you’ve found your polar, select it and it will be confirmed.

Comment importer une polaire?

The application can import polars in the .pol format.

To import your own polar:

1. Go to the “My Boat” tab, then tap the selected Polar.
2. Select the “Imported” tab.
3. Click on the “Import a Polar” button.
4. Choose your .pol polar file saved on your computer or smartphone.
5. Once imported, click on the polar to select it.
6. The polar is then validated.
   
   Advantage: If you are logged into your NavimetriX account, the imported polar is automatically synchronized across all your devices!
   
   

iPolar lets you create a polar in one minute based on your boat’s characteristics:

1. Go to the “My Boat” tab, then tap the selected Polar.
2. Select the “iPolar” tab, then click “Create”.
3. Enter the required information:
   • Polar name
   • Overall length
   • Displacement
   • Main sail area
   • Jib area
4. Optional information:
   • Waterline length
   • Symmetrical spinnaker area
   • Asymmetrical spinnaker area
5. Choose your parameters:
   • Sailing style: Cruising or Racing
   • Polar type: Routing or Performance
   • (For most users: Cruising + Routing)
6. Click “Calculate my polar”.
7. Select your newly created polar.

Note: The iPolar method was developed by KND, experts who work with the America’s Cup, TP52s, and IMOCAs — the best in their field!

Some polars are formatted as .CSV (Comma Separated Value) files, where the field separator is a comma or semicolon. This format is not supported in NavimetriX, unlike the .POL format where fields are separated by tabs — a format widely used in navigation applications. Therefore, you need to convert your .CSV file to .POL.

With Excel (Windows / macOS)

Open a new Excel sheet and select the menu: File > Import.

Choose “CSV File” and then select your polar file from the Finder.

Check the box Delimiters = “Semicolon”, then insert the data into the existing sheet.

Then save the file in “Text (Tab delimited)” format, which will create a .TXT text file.

Finally, rename the file by replacing the .TXT extension with .POL:

Your polar file is now ready to be imported.

With Numbers (macOS)

Open the .CSV file with Numbers:

Export the file to TSV:

Replace the file .TSV extension to .POL, that's all.

On the chart, the course vector on the ground COG is represented by a red arrow. The magnetic heading line is represented by a green line. Both are variable in length.

Open the app settings by tapping on the ⚙︎ icon, then select the My Boat section.

• The length of the heading vector is defined in minutes of time, from 0 up to 300mn. In example, 30 minutes on course at a 6 knots speed displays a vector of 3 nautical miles. This vector varies depending on your speed. You can disable the arrowhead.
• The heading line is set by distance on the chart, from 0 up to 300 NM. In example 20 nautical miles.

Open the app settings and select ‘My boat’. The track settings are at the bottom of the list.

You are able to:

• Enable/disable the display
• Adjust the duration, from 0 up to 365 days
• Select track width display (pixels)
• Select track color
• Choose whether or not to display wind barbules on the track
• Choose whether or not to display current vectors on the track
• Adjust the frequency of the wind/current display
• Clear track
• Export the track (GPX/KML format)

Procedure:

<li>Close <strong>NavimetriX</strong>.</li>



<li>Right-click the NavimetriX shortcut (or the <code>NavimetriX.exe</code> file in its installation folder).</li>



<li>Select <strong>Properties</strong>.</li>



<li>Open the <strong>Compatibility</strong> tab.</li>



<li>Click <strong>Change high DPI settings</strong>.</li>



<li>Check the option:<br><em>Override high DPI scaling behavior.</em></li>



<li>In the dropdown menu below, choose <strong>Application</strong>.</li>



<li>Click <strong>OK</strong>, then <strong>Apply</strong>.</li>



<li>Restart <strong>NavimetriX</strong>.</li>



<li>Text and interface elements should now appear larger.</li>

By default, the target is placed in the center of the screen, allowing you to drag the map underneath it and use the zoom to position it at a specific location.

However, you can lock the target to other elements, or even disable it.

Tap/click on the layers button.

In the “Target” drop-down menu, select which element you want to lock the target to:

• Disabled (to remove the target from the screen)
• Screen center (to place it to its original location)
• GPS position (to place it on your boat)
• A POI

You can also lock the target onto a POI by editing it.

If you do not see NMEA sentences scrolling in the NavimetriX NMEA console, this may be related to the limitations of the WiFi module integrated in the box, which is now end of life. This module is no longer fully compatible with certain devices, in particular the most recent mobile devices.

Check the box software version
Before performing any other action, it is essential to verify that your NKE WiFi box is running the latest internal software version. The currently available version is version 2.5. A box running an older version may experience WiFi connection issues.
You can check the version of your box directly on your MultiGraphic or Multi Display, or using the TopLink software. The software update must be performed using the TopLink software.

Download and install the TopLink software
Checking and updating the software of the NKE WiFi box is done using the TopLink software. This software runs only on Windows PCs. To download it, go to the NKE website, click on the hamburger menu at the top right, then access the Technical access section. From there, open the TopLink software page, download the program, and install it on your computer.

Update the NKE WiFi box
Once TopLink is installed and launched, connect to your NKE WiFi box and perform the update to version 2.5.

Case of recent Apple devices
On some Apple devices (iPhone or iPad) running iOS versions higher than iOS 17 (versions released from 2024 onwards), a WiFi security mechanism added by Apple prevents connection to the NKE WiFi box, even when the box is up to date.
In this case, the WiFi must be forced into open mode, without a password.
To do this, press and hold the Init button on the NKE WiFi box for exactly 8 seconds. It is important to respect this duration precisely; you will hear 8 beeps. This action forces the box WiFi into open mode (no password), allowing affected Apple devices to connect.
Finally, restart the box.

Once connected to the box WiFi, access to the NKE WiFi box should be restored and you should see the NMEA sentences in the NavimetriX console.

A GRIB file (for GRIdded Binary) is a standard file format used by meteorological services to distribute numerical weather forecasts.

It contains the raw data generated by weather models (wind, pressure, rain, waves, currents, etc.) organized on a grid covering a geographic area.

Why use this format?

• It is compact: GRIB files are compressed and therefore quick to download, even with limited internet connections.
• It is standardized: most navigation and weather applications can read GRIB files. There are two formats — grib1 and grib2. NavimetriX uses the newer grib2 format.
• It is flexible: you can choose the area, resolution, and parameters (wind, waves, currents, etc.) you wish to download.

What does a GRIB file contain?

Depending on the selected model, a GRIB file may include:

• Wind (direction, speed, gusts)
• Atmospheric pressure
• Temperature, humidity, precipitation
• Sea state (swell, waves)
• Marine, oceanic, and tidal currents

What is it used for in navigation?

A GRIB file allows you to visualize the evolution of the weather over a given area directly within your navigation software or weather app.

To illustrate the process, let’s say we’re planning a 4-day passage from La Rochelle (France) to Cowes (UK).

• Pan and zoom to your sailing area. Unless you’re doing an ocean crossing, pick a selection slightly larger than your route.
• Press the + button.
• Tap Download GRIB.
• If needed, adjust the selection using the four green corners.
• Press OK.

A Download GRIB window opens. The choices are filtered to your selected region.
Without the Premium option, you’re limited to the GFS model (the U.S. NOAA global atmospheric model).

• Choose the Type of data to download:
  • Atmospheric
  • Current
  • Sea State
• Choose the Coverage:
  • Global
  • Regional — for trips up to ~5 days, a regional model is usually best.
• If applicable, select the Region.
• Select the Model.
  See our FAQs for guidance on models.
  If unsure, choose the atmospheric global ECMWF IFS or GFS.
• If needed, check the Model description & coverage map.
• Select the Days and Timestep.
  If unsure, keep the defaults.
• Choose the Parameters (Wind, Pressure, etc.).
  If unsure, keep the defaults.

The estimated compressed GRIB size appears at the bottom. Keep it reasonable—if you see ~200 MB, you probably chose a model that’s too fine or too many parameters.

Below the model description, we show the latest model calculation time (the Run).
Run: 20251016 12Z +102 means: calculated on Oct 16, 2025; initialized at 12:00 UTC (12Z); contains 102 forecast hours from that run.
We also display the estimated time until the next run is available.

• Press Download GRIB.
• The GRIB file downloads from our fast, redundant servers.
• Once downloaded, it is:
  • displayed on the map. If you don’t see it, open Layers and enable Color map and Barbs.
  • added to the GRIB list in the left panel. Tap the ☰ at top-left to open the lists panel.

You may have noticed a small icon on the right of each item in the GRIB files list. This icon shows the update status of your GRIB file and can display three different states:

1. Dark orange “Refresh” icon — file up to date

The icon appears in dark orange right after a GRIB file has been downloaded. This means your file is up to date — you already have the latest available version of the weather model.
This is what you will see immediately after downloading a GRIB file.

2. Light orange “Refresh” icon — new run available

The icon turns light orange. This means a new model run (a new forecast) is available. To update your GRIB file, simply click or tap on this icon: the file will automatically be replaced with the latest version.

3. Light orange icon with a download symbol — file missing on this device

Finally, the icon may appear in light orange with a small download symbol. This means you have already downloaded this GRIB file on another device, but it is not yet available locally on the one you are using. To retrieve it, simply click or tap on the icon: the file will be downloaded automatically.

See also: Where can I see weather models status

Global models (such as GFS or ECMWF) cover the entire planet. They are essential for long crossings and long-term forecasts (up to 10–15 days), but their resolution remains limited (20 to 50 km). They are used to get an overall view of the weather and for long-distance passages.

Regional models focus on a specific area (France, Europe, the Mediterranean…). Their coverage is smaller, but their resolution is much finer (2 to 10 km), allowing for better anticipation of local effects such as thermal breezes, thunderstorms, terrain, and coastal winds. In return, they generally only extend 2 to 3 days into the future. They are used for day trips or short cruises.

If you’re not familiar with weather models, you’re probably wondering which ones to choose.
Here are a few simple rules:

Select the model according to your navigation area and type of sailing, following the table below.

For weather data, if in doubt, choose the ECMWF IFS model.
The ECMWF IFS model covers the entire globe for up to 14 days. However, note that forecast reliability decreases with time:

Here’s a table to help you choose. We’ll soon add an automatic selection feature based on your sailing program.

• Arome HD 0.01° (1 km)
  Even higher-resolution version of Météo-France’s Arome model.
  Resolution: 1 km
  Forecasts over 24 h
  👉 Very useful for racing or coastal sailing: it helps anticipate micro wind shifts near capes, bays, or coastal terrain. Be aware, it can sometimes be a bit “reactive.”

• ECMWF IFS 0,1° (9 km) 0.25° (28 km), 0.4° (44 km), 1° (111 km)
  Global model from the European Centre (ECMWF). Often considered the most reliable for medium-range forecasts.
  Resolution: from 29 km up to 111 km
  Forecasts up to 10 days
  👉 A key reference for offshore navigation. Prefer the high-resolution version (0,1°) for a small area, (0.25°) with a good connection for a larger area, or a lighter version (0.4° or 1°) when bandwidth is limited and the area very large. 

• ECMWF AIFS 0.25° (28 km), 1° (111 km)
  Brand-new model from the European Centre (ECMWF) using artificial intelligence.
• Resolution: 28 km or 111 km
• Forecasts up to 10 days
• 👉 Interesting for testing AI model performance and having an alternative to traditional models. Improving day by day — already likely better than ECMWF IFS and GFS for forecasts beyond 7 days.

• GDPS (GEM) 0.15° (17 km)
  Global model produced by Environment Canada. One of the finest-resolution global models available.
  Resolution: 17 km
  Forecasts up to 10 days
  👉 Relevant for North Atlantic crossings and high-latitude sailing near the Arctic.

• ICON Global 0.25° (28 km)
  Global model from DWD (German Meteorological Service).
  Resolution: 28 km
  Forecasts up to 7 days
  👉 A solid alternative to GFS and ECMWF IFS, particularly for sailing in Europe and the Mediterranean.

• Arpege Global 0.25° (28 km)
  Global model from Météo-France.
  Resolution: 28 km
  Forecasts up to 10 days
  👉 Useful for offshore sailing near France, in the Atlantic or Mediterranean, as it is well tuned for these areas.

These models provide a simplified description of the sea state.
In short, they include the significant height of the total sea, its period, its direction, as well as the same information for the wind sea.

They are mainly used in routing when conditions are challenging.

Global Models

• GFS 0.25° (28 km), 0.5° (56 km), 1° (111 km), 2° (222 km)
  Global model from NOAA (United States). Available in several resolutions: the finer the grid, the larger but more accurate the file.
  Resolution: from 28 km to 111 km
  Forecasts up to 16 days
  Time step: 3 hours
  A key reference for offshore navigation. Prefer the fine version (0.25°) with a good connection, or a lighter version (1° or 2°) when bandwidth is limited.
• MFWAM Global 0.1° (12 km), 0.5° (56 km), 1° (111 km)
  Global model from Météo-France. Available in several resolutions.
  Resolution: from 12 km to 56 km
  Forecasts up to 4 days
  Time step: 3 hours
  The most accurate of the global models, but limited to 4-day forecasts.

Regional Models

• MFWAM France 0.025° (3 km)
  Regional model from Météo-France.
  Covers the French metropolitan coasts.
  Grid: 0.025° x 0.025° (3 km x 3 km)
  Total forecast range: 4 days
  Time step: 3 h
  Excellent for coastal navigation.
• IFREMER WW3 0.006° (500 m)
  Regional models from IFREMER with several variants: North and South Channel, and North and South Gascogne.
  Covers the Channel and Atlantic coasts of mainland France.
  Grid: 0.004° x 0.006° (500 m x 1 km)
  Total forecast range: 2 days
  Time step: 1 h
• IFREMER WW3 0.003° (250 m)
  Local models from IFREMER with several variants:
  Pas-de-Calais, Normandy-Cotentin, Armor, Finistère, South Brittany, Loire, Charentes, and Aquitaine.
  Covers the Channel and Atlantic coasts of mainland France.
  Grid: 0.002° x 0.003° (250 x 500 m)
  Total forecast range: 2 days
  Time step: 1 h
  The most accurate wave model — a must when sailing through tricky coastal areas.

Weather Models

European Atmospheric Models

American Atmospheric Models

Wave Models

Current Models

See also: It’s great to have all these models — but which one should I choose?

Wind Settings

Open the Settings panel by tapping the cogwheel at the top right of the upper ribbon, then select GRIB Display.

• Wind Display

In the “Wind” section, select Particles or Barbs. Animated particles show the wind flow but consume more system resources and therefore battery — best avoided while sailing. Vectors and barbs are the classic meteorological representation of wind direction and strength. They are positioned on each grid point of the GRIB file and are more resource-efficient.

The Gradient style represents wind strength using a rainbow color scale — from blue (light or calm winds) to magenta (strong winds), through shades of green, yellow, orange, and red. Especially suitable for wind data.

The Isoplane style displays the data with the same colors but as equal-value zones. This style is better suited for data such as wave height, for example in 50-cm increments.

The Land Mask displays data over land as well. This is particularly useful when sailing among islands, to keep a continuous sea/land display.

Transparency allows you to adjust the color overlay depending on the background (satellite map or nautical chart).

The Iso-zone step adjusts the spacing between isoplane zones depending on the type of data (waves, precipitation, temperature, etc.).

Wind Display

On the map, the Layer button at the bottom right of the screen lets you choose what to display.

In the GRIB Display section, the drop-down menu allows you to select which data to display. If a weather GRIB (for example an IFS model) is displayed, Wind will be selected by default. You can enable or disable the color background, particles or barbs (according to your previous setting above), and isobars (lines of equal atmospheric pressure).

If you have displayed a wave GRIB file, you can enable or disable the color background and the wave direction arrows.

This section automatically adapts to the type of GRIB file displayed on the screen: weather, waves, or currents.

By default, a tide gauge is displayed on the cartography for each referenced station.

The display can be disabled by opening the layers menu and unchecking the Tide box. The gauges currently display dynamically:

• Flow in green
• Ebb in red

Tapping on each gauge opens a tide graph showing the tide curve and the current water level, represented by the vertical timeline.

The graph is topped by a table showing the times, water heights and tidal coefficients for the day.

Tapping/clicking on the date above the table opens the calendar, allowing you to select another day/month.

The height threshold can be used to determine:

• What the water level will be at a given time
• What time a given threshold will be reached

NavimetriX offers several high-resolution regional models for popular sailing destinations worldwide, in addition to global models like GFS, ECMWF, and ICON Global.

North America

NAM (11 km resolution) — NOAA's North American Mesoscale model covers the continental United States. Forecasts up to 84 hours with hourly time steps. Ideal for coastal navigation along the US East Coast, West Coast, and Gulf of Mexico.

HRRR CONUS (3 km resolution) — The High-Resolution Rapid Refresh model provides the finest resolution for the continental US. Forecasts up to 18 hours, updated hourly. Perfect for racing and detecting rapidly evolving conditions like sea breezes and thunderstorms.

Caribbean & South America

Arome Antilles (3 km resolution) — Météo-France model covering the Lesser Antilles from Puerto Rico to Trinidad. Forecasts up to 48 hours. Excellent for inter-island passages and detecting trade wind variations.

Arome Guyane (3 km resolution) — Covers waters off French Guiana and the nearby South American coast. Forecasts up to 33 hours. Useful for sailors transiting between the Caribbean and Brazil.

Pacific Islands

Arome Polynésie (3 km resolution) — Covers French Polynesia including Tahiti and the Society Islands. Forecasts up to 48 hours. Ideal for detecting local effects around high volcanic islands and reef passes.

Arome Calédonie (3 km resolution) — Covers New Caledonia and the Coral Sea. Forecasts up to 48 hours. Essential for navigating the lagoon system and anticipating thermal effects around Grande Terre.

Indian Ocean

Arome Réunion-Mayotte (3 km resolution) — Covers the western Indian Ocean from the Mozambique Channel to the Mascarene Islands, including Madagascar, Réunion, Mauritius, and Mayotte. Forecasts up to 48 hours. Critical for this cyclone-prone region.

Read also: Why are there global models and regional models

NavimetriX provides access to over 70 weather, wave, and current models from leading meteorological agencies worldwide.

🌍 Atmospheric Models — Global

GFS — NOAA — 28 to 222 km — 16 days

ECMWF IFS — ECMWF — 9 to 111 km — 15 days

ECMWF AIFS — ECMWF — 28 to 111 km — 15 days

ICON Global — DWD — 14 to 111 km — 5 days

Arpège Monde — Météo-France — 28 km — 4 days

GDPS (GEM) — CMC Canada — 17 km — 10 days

🇪🇺 Atmospheric Models — Europe

Arpège Europe — Météo-France — 11 km — 4 days

Arome — Météo-France — 3 km — 42 hrs

Arome HD — Météo-France — 1 km — 36 hrs

ICON Europe — DWD — 8 km — 5 days

ICON D2 — DWD — 2 km — 48 hrs

UKV — Met Office — 6 km — 5 days

🌎 Atmospheric Models — Americas

NAM — NOAA — 11 km — 84 hrs

HRRR CONUS — NOAA — 3 km — 18 hrs

Arome Antilles — Météo-France — 3 km — 48 hrs

Arome Guyane — Météo-France — 3 km — 33 hrs

🌏 Atmospheric Models — Pacific & Indian Ocean

Arome Polynésie — Météo-France — 3 km — 48 hrs

Arome Calédonie — Météo-France — 3 km — 48 hrs

Arome Réunion-Mayotte — Météo-France — 3 km — 48 hrs

🌊 Wave Models (Sea State)

GFS Wave — NOAA — Global — 28 to 111 km — 16 days

MFWAM Global — Météo-France — Global — 11 to 56 km — 4 days

MFWAM France — Météo-France — France — 3 km — 4 days

IFREMER WW3 — Ifremer — France coasts (14 zones) — 190m to 500m — 4 days

🔵 Oceanic Current Models — Global

Copernicus Global — Copernicus — 9 km — 5 days — oceanic currents only (Gulf Stream, etc.)

🔵 Oceanic and tidal Current Models — Global

Copernicus Global SMOC — Copernicus — 9 to 56 km — 5 days

🔵 Oceanic and tidal Current Models — Europe

Copernicus IBI — Iberian-Biscay-Ireland — 3 km — 5 days

Copernicus ENWS — NW Shelf / North Sea — 2 km — 5 days

Copernicus BALTIC — Baltic Sea — 4 km — 5 days

Copernicus MED — Mediterranean — 5 km — 5 days

SHOM Manche-Gascogne — Channel & Biscay — 2 km — 5 days

SHOM Méditerranée Nord — NW Mediterranean — 2 km — 5 days

IFREMER — France coasts (10 zones) — 250m to 3 km — 4 days

🔵 Oceanic and tidal Current Models — Americas

MSC Saint Laurent — St. Lawrence / Atlantic Canada — 1 km — 84 hrs

NCOM Alaska - N. Calif — Alaska to N. California — 4 km — 90 hrs

NCOM Caribbean — Gulf of Mexico & Caribbean — 3 km — 90 hrs

NCOM Hawaii — Hawaii — 4 km — 90 hrs

NCOM South California — Southern California — 4 km — 90 hrs

NCOM US East Coast — US East Coast — 4 km — 90 hrs

Read also: Why are there global models and regional models

In order to rename a GRIB file, you have to do a long click/tap on its name. This will bring up the keyboard, allowing you to change the name:

The name will be preserved during updates and synchronization.

Check our real-time model status page by following this link:

See weather models status

How to Read Marine Weather Charts (Surface Analysis Charts)

Surface analysis charts are essential tools for any sailor. They provide a synoptic view of current weather conditions and help anticipate weather changes. This guide explains how to interpret the symbols and information on these charts.

What is a Surface Analysis Chart?

A Surface Analysis Chart is a representation of weather conditions at the Earth's surface at a given time. These charts are produced by national weather services such as NOAA (USA), the Met Office (UK), or Météo-France.

They use a combination of lines, symbols, and color codes to represent:

• Pressure systems (highs and lows)
• Weather fronts
• Isobars (lines of equal pressure)
• Weather station observations
• Precipitation areas

Pressure Systems: Highs (H) and Lows (L)

Pressure systems are the main drivers of weather. They are indicated by the letters H (High pressure) and L (Low pressure).

High Pressure (H) - Anticyclone

Low Pressure (L) - Depression

💡 Navigation tip: A low with pressure below 980 mb is considered deep. NOAA charts sometimes indicate "GALE" (34-47 knots), "STORM" (48-63 knots), or "HURRICANE FORCE" (≥64 knots) near intense lows.

Isobars: Lines of Equal Pressure

Isobars are the thin lines connecting points of equal atmospheric pressure. They are typically spaced 4 millibars apart (1008, 1012, 1016, 1020 mb, etc.).

Key rule: Isobar spacing indicates wind strength:

Closely spaced isobars	→	Strong gradient = Strong winds
Widely spaced isobars	→	Weak gradient = Light winds

💡 Buys-Ballot's Law: In the Northern Hemisphere, if you stand with your back to the wind, low pressure is always on your left. Wind blows parallel to isobars (with a slight angle toward low pressure due to friction).

Weather Fronts

Fronts are boundaries between different air masses. Their passage typically brings significant changes in temperature, wind direction, and weather conditions.

Cold Front

Symbol: Blue line with triangles pointing in the direction of movement

Description: Cold air mass pushing into warm air. Cold fronts move faster (25-30 knots) because the denser cold air undercuts the warm air.

Weather at passage: Thunderstorms or intense but brief showers, rapid wind shift (SW → NW), sharp temperature drop, quick clearing after passage.

Warm Front

Symbol: Red line with half-circles pointing in the direction of movement

Description: Warm air mass sliding over cold air. Slower (10-15 knots) because warm air must ride up over cold air.

Weather at passage: Prolonged steady precipitation, stratiform clouds (cirrus → altostratus → nimbostratus), reduced visibility, possible fog, gradual temperature rise.

Stationary Front

Symbol: Alternating blue triangles and red half-circles on opposite sides of the line

Description: Two air masses that aren't moving relative to each other. Can persist for several days.

Associated weather: Prolonged overcast conditions, persistent precipitation over the area, stagnant conditions.

Occluded Front

Symbol: Purple line with alternating triangles and half-circles on the same side

Description: The faster cold front catches up to the warm front. Warm air is lifted aloft.

Associated weather: Mixed conditions, varied precipitation. Significance: The low is reaching maturity and beginning to weaken.

Other Boundaries

Trough

Symbol: Brown/orange dashed line in a U or V shape, often marked "TROF"

Description: Elongated area of relatively low pressure, without being a true front.

Associated weather: Atmospheric instability, wind convergence, risk of thunderstorms or unsettled weather.

Squall Line

Symbol: Line with two red dots, often marked "SQLN"

Description: Organized line of thunderstorms, often located ahead of a cold front.

⚠️ DANGER: Violent winds, possible hail, destructive gusts. Potentially dangerous conditions for navigation!

Dry Line

Symbol: Orange/brown line with half-circles pointing toward moist air

Description: Boundary between dry continental air and moist maritime air (common in the US between Gulf of Mexico air and Southwest desert air).

Associated weather: Violent thunderstorm development along the line, especially in spring/summer.

Tropical wave

Symbol: Wide dotted red line.

Description: Rainy and stormy front moving from east to west in the intertropical zone. Frequent during the hurricane season between Africa and the Caribbean.

Associated weather: Squalls, sometimes intense, which can develop into tropical storms and then hurricanes as they progress.

📥 Complete reference: Official WPC/NOAA Front Legend

Weather Station Observations (Station Plots)

Detailed charts display weather station observations as station plots. These compact symbols summarize a lot of information at a glance.

Station Plot Elements

Position	Information
Center	Cloud cover (● overcast, ◐ partly cloudy, ○ clear)
Upper left	Temperature (°F or °C)
Lower left	Dew point
Right	Pressure (last 3 digits: 218 = 1021.8 mb)
Extending line	Wind direction (where it's coming from)
Barbs	Wind speed (see below)

Reading Wind Barbs

Wind barbs indicate wind speed. Add the symbols together to get the total speed:

💡 Example: 1 pennant + 2 full barbs + 1 half barb = 50 + 20 + 5 = 75 knots

Precipitation Symbols

Symbol	Description
	Rain (more dots = heavier)
	Snow
	Drizzle
	Showers
	Thunderstorm
	Fog

📥 Download: Complete Weather Symbol Guide (PDF) - NOAA

Understanding "Ahead" and "Behind" a Front

These terms refer to front movement, not geographic direction:

💡 Practical application: If a forecast says "showers behind the cold front," expect precipitation AFTER the front passes through your location.

Common Units

Chart Sources and Frequency

Technical References

Official documentation:

• NOAA Unified Surface Analysis Manual (PDF) - Complete 33-page technical reference
• NOAA JetStream - Surface Weather Maps - Official NOAA online tutorial
• WPC Front Codes - Official front symbol reference

Additional learning resources:

• How to read Surface Weather Maps (NOAA JetStream) - Official NOAA guide with illustrations
• Surface Weather Plots (NOAA JetStream) - Station plot details

The SHOM Tidal Current Atlas is available for use in routing settings, in addition to GRIB format models (¹).

The Atlas data can be displayed as particles on the chart.

Tap/click on the layer display button, then check “Current Atlases”:

You can overlay this display with a high-resolution GRIB from Ifremer, for example, in order to compare them by dragging the timeline:

Tip: adjust the zoom according to the circumstances for better readability.

–––

(¹) See: How do I calculate a routing?

Numerous weather surface analysis maps, also known as isobaric or fronts maps, are available in the application to supplement GRIB files and facilitate the interpretation of weather situations and forecasts.

These charts come from various meteorological agencies and are produced by forecasters: NOAA (USA), MetOffice (UK), BOM (Australia), etc. A special chart for observing Sargassum off the coast of the Caribbean is also provided by USF (University of South Florida). All are stored on our own servers and to download from it.

Open the Hamburger menu and select the “Maps” tab.

The Maps menu is dynamic, offering maps available according to the target's location on the world map.

Displaying NOAA weather maps

NOAA maps range from current analysis up to 4-day forecasts, updated every six hours.

Overlaying NOAA weather maps with GRIBs

Overlaying the NOAA map with the GFS file provides additional insight with the drawing of fronts and specific annotations.

Displaying MetOffice weather maps

MetOffice maps are not in a format that allows them to be overlayed on the nautical chart in 3D. They are therefore displayed in their original format, in color or black and white. They only cover the Northeast Atlantic and Europe. They range from current analysis up to 5-day forecasts.

Sargassum map

Published by the USF, the sargassum density map covers the eastern Caribbean from W38 to W62 and from N20 to the Equator. It is updated daily. It is mainly of interest for crossings to the West Indies.

Satellite images

Three types of satellite images are available, covering the entire world. They are taken from different weather satellites and provide a near real-time view of cloud cover and precipitation.

Tap/Click on the layers button and select the “Realtime satellite” option in the Maps section.

High Res IR, Global IR, and NOAA IR are combinations of infrared images that display cloud cover, and precipitation totals for the first two. By combining a satellite image and an isobaric map, you can obtain an instant view of weather conditions.

The color coding of precipitation totals on radar images follows the scale below (source: Météo-France) :

For information on interpreting frontology (isobaric) maps, see this FAQ: How to read marine weather maps.

“In-situ” weather stations provide instant weather readings that allow you to compare this data with weather model forecasts. These stations can be semaphores along the coastline, fixed or floating buoys at sea, accredited ships, airports on land, or weather satellites.

How to display them?

Tap/click on the layers menu and check the “Weather stations” box in the Display section.

The stations are represented by an “arrowhead” symbol that takes the orientation of the “wind direction” data and the colorimetry of the “wind strength.”

Tapping/clicking on a symbol opens a window displaying the characteristics of the station and the most recent data values.

Station types and their info data

If the time of the information is within the coverage period of the displayed GRIB file, then tapping/clicking in the center of the popup centers the map on the station's coordinates and returns the timeline to the exact time of the station, allowing you to compare the data value and the GRIB file forecast.

Change the weather data display in Navimetrix:

1. Open the Settings menu: tap the gear icon in the top right corner.
2. Go to the “Forecast display” section: you will see four blocks, each corresponding to a type of weather data:
   • Wind
   • Pressure
   • Currents
   • Waves
3. Customize the Wind display:
   • Barbs: classic display with arrows and small barbs indicating strength.
   • Particles: small animated particles representing the flow. Very effective for visualizing the wind, but be careful of battery consumption.
   • Color map style: Gradient, continuous color variation, or Iso areas, according to wind intensity.
   • Land mask: allows you to easily distinguish land areas.
   • Transparency: adjust the visibility of the colored background.
   • Step between iso zones: adjust the fineness of the wind ranges displayed.
   • Iso areas step: display by ranges (e.g., 5-10 knots, 10-15 knots).
4. Customize the pressure display:
   • Color map style: Gradient, continuous pressure visualization, or Iso areas (isobars): pressure lines spaced at an interval that you can adjust.
   • Isobar step: spacing of isobars in hectoPascals.
5. Customize Currents display:
   • Classic arrows: direction and strength of currents.
   • Animated particles: small animated particles representing the flow. Very effective for visualizing large-scale currents, but be careful of battery drain.
   • Color map style: Gradient, continuous current values visualization, or Iso areas (isobars): current values spaced at an interval that you can adjust in knots.
6. Customize Waves display:
   • Waves are always represented by arrows indicating the direction.
   • Color gradient: continuous visualization of wave height.
   • Iso areas: wave height spaced at intervals that you can adjust.

Tip: use Particles display mode or Iso areas for better reading of large-scale conditions. For sea navigation, use Barbs and Isobars, which are more accurate and less resource-intensive.

You check the weather forecast before setting sail: southwesterly wind 15 knots, slightly rough seas. Perfect. But how reliable is this forecast? Could it just as easily be 10 knots… or 25? This is exactly the question that an ensemble model answers.

One forecast is good. Thirty-one is better.

A standard weather model such as the GFS produces a single forecast: the best available estimate of the future atmosphere. The problem is that the atmosphere is chaotic—tiny differences in initial conditions can lead to very different outcomes a few days later.

An ensemble model such as NOAA's GEFS (Global Ensemble Forecast System) takes a radically different approach. Instead of running a single simulation, it runs 31 in parallel:

• 1 control run (gec00): the reference simulation, without perturbation
• 30 perturbed members (gep01 up to gep30): each starts from slightly different initial conditions, simulating the natural uncertainty of observations

Result: instead of a single scenario, you get 31 possible futures. If the 31 forecasts converge, confidence is high. If they diverge, it is a clear signal that the situation is uncertain and caution is needed.

The average GEFS model displays wind and pressure with their standard deviation, providing an overview of the uncertainty.

Average and standard deviation: see the uncertainty at a glance

The average GEFS model provides, for each point on the grid, two information:

• The average wind (or pressure) value calculated over the 31 members.
• The spread: the dispersion around this average.

Statistically, there is approximately a 68% chance that the actual value will fall within the range “average ± 1 spread.” In other words, if the average is 15 knots with a 3 knots spread, there is about a 2 in 3 chance that the actual wind will be between 12 and 18 knots. A low spread means a reliable forecast; a high spread means a high degree of uncertainty.

Why it's essential for navigation

While sailing, the weather determines your route, your speed, and your safety. Here's what an ensemble model gives you in concrete terms:

1. Quantifying uncertainty

A classic deterministic model tells you: “15-knot wind.” An ensemble model tells you: “average wind speed of 15 knots, with a spread of 3 knots — so between 12 and 18 knots in 68% of cases.” This information is invaluable for choosing the right sails, planning a backup, or simply deciding whether it's the right time to set sail.

2. Evaluate the reliability of your routing

Your weather routing gives you an optimal route — but this route is calculated based on a single scenario. What happens if the wind shifts 20°? If the low pressure system moves faster? Ensemble routing calculates the optimal route for each of 31 scenarios. If all routes pass through the same location, you can proceed with confidence. If they diverge, caution is advised.

3. Anticipate beyond 5-7 days

The reliability of a classic model declines rapidly after 5-7 days. The ensemble model, on the other hand, remains useful beyond that point, not because it predicts better, but because it shows you how uncertain the forecast is. When the 31 members diverge on D+7, you know it's still too early to decide; that's already very useful information!

GEFS in NavimetriX: easy and accessible

Until now, using an ensemble model was the stuff of professional meteorologists and offshore racing skippers. NavimetriX is changing that by making this data accessible to all sailors:

• Integrated download: the average GEFS model can be downloaded like any other GRIB file, directly from the application (select “Ensemble” from the GRIB request drop-down menu).
• Spread visualization: wind and pressure fields display their dispersion, allowing you to see at a glance where the forecast is reliable and where it is not.
• One-click ensemble routing: NavimetriX automatically downloads and calculates the 31 routes: no need to manipulate files or run scripts.
• Intuitive display: colored “spaghetti” routes and confidence corridor directly on the chart.

The ensemble model is no longer just for experts. It is a tool that helps all sailors make better decisions by transforming uncertainty into visual, clear, and usable information.

The term “waypoint” doesn’t exist in NavimetriX. Instead, we use POI (Point Of Interest), a more generic term that can include many elements (targets, anchorages, beacons, race marks, etc.).

On a tablet or smartphone

Drag the map under the target on the screen, zooming in to position it accurately.

Tap the + icon in the bottom right corner of the screen and select ‘Add POI’ from the menu.

• Enter the name of the point
• Select an icon from the drop-down list
• Choose whether to display the name on the chart
• Enter a specific latitude and longitude manually
• Check if the format is right

Tap OK to confirm.

On a Mac or PC

Place the mouse or trackpad pointer on the desired location on the map, without worrying about the target, and right-click. In the popup that appears, select “Add a POI”. The creation window opens as shown here.

Alternatively, you can proceed the same way as on a tablet or smartphone.

Saving

The points are saved in the POI list, located in the left sidebar of the screen, accessible via the ≡ symbol in the top-left toolbar.

You can show or hide each point individually by tapping the eye icon on the right side of the column.

Adjusting POI display

You can adjust the display so that the name and optional icon appear only from a certain zoom level, preventing the map from becoming overloaded if you have many points.

On a tablet or smartphone

Move the chart under the target displayed on the screen, zooming in for precise positioning, then tap the + icon in the lower right corner. From the menu, select “Create a route”.

Tap successively to place the desired points. You can drag them with your finger to move them if needed. Zoom in for more precise placement. Once finished, select the “Finish” button at the top of the screen. Enter a name for your route and confirm saving by tapping “OK”.

On a Mac or PC

Click to create successive points, zooming in for better accuracy. You can also drag the points to adjust their position if needed. Click the “Finish” button at the top of the screen. Enter a name for your route and confirm saving by clicking “OK”. Alternatively, you can proceed the same way as on a tablet or smartphone.

In any case, you can also create a route by tapping or clicking an existing POI (waypoint) and selecting “Begin route” from the popup menu starting from that point.

Saving

Routes are saved in the Routes list, located in the left sidebar of the screen, accessible via the ≡ symbol in the top-left toolbar.

Tap the "eye" icon next to each route to toggle its display on or off. Use the checkboxes to select routes for export or remove.

Reverse / create a route

A "Table" icon allows you to open the detailed route info. Tap/clic "Reverse route" button to sail back, "Duplicate route " to make a copy of the route.

Tap or click, depending on your device, on a POI, and in the menu that appears select “Edit POI” to open the edit window.

See also: How do I create a POI or waypoint

Open the left sidebar and select the “Routes” section. Display the route on the map by activating the “eye” symbol, then tap or right-click (depending on your device) on any part of the route. In the menu that appears, choose the option “Edit route”.

See also: How do I create a route?

• Check that the option to display POIs is enabled.

• If POIs only appear when zoomed in too far, lower the zoom level at which they become visible using the option: “Show details for zoom levels over”.

• Edit the route.
• Edit the waypoint.

• Change the default “Pass by” to “Leave to starboard” or “Leave to port.”
• The point is green for Leave to Starboard and red for Port.

• Finish then save the route

Import POIs

Open "hamburger" menu and select tab POIs :

You can import POIs with extension GPX, KML, and WP (format used by Adrena).

Import routes

Open "hamburger" menu and select the tab Routes:

You can import routes with extension GPX, KML, and RT (format used by Adrena).

Route tracking allows you to set the boat to automatically navigate through each point on a route. If you control your autopilot by sending it NMEA data (*), it will steer the boat by following the successive legs from one point to the next.

Start route tracking

1. First, display a previously created route.
2. Tap or click on the first waypoint from which you want to start tracking.
3. Select "Follow route, start here

Activating this feature displays a course deviation corridor, which you can define in Settings > My Boat > Cross-Track:

The cross-track corridor follows all points on the route:

Stop tracking

You can stop tracking or reset the cross-track at any time:

Cross-Track Alarm

You can enable an alarm if the boat leaves the cross-track corridor.

1. Select the Alarms section in the app’s Settings.
2. Set the width of the corridor on either side of the direct route.
3. Choose a sound from the drop-down menu.

————

(*) See: How to send NMEA data to instruments

ZOIs are areas to avoid or areas of particular interest. Some are pre-existing in the application, but you can create as many as you need. There are three types:

• No Go Zones: Traffic Separation Systems (TSS), wind farms, protected environmental areas, shallow waters, etc., drawned in red
• Slow Zones: Sargassum fields, speed-restricted areas, areas where sea-state is dangerous, etc., drawned in orange.
• Information Zones: areas of particular interest for navigation, drowned in blue.

Only no go zones and slow zones are considered by the routing calculation, if they are displayed on the chart. In the left side menu list, you can enable/disable the display of a zone on the chart by tap/click on the eye icon, select one or more zones to export or delete them by checking the box(es). You can also import ZOIs.

Create a ZOI

Modify a ZOI

Tap/click on the border of a ZOI to edit/delete it. You can move the borders by selecting the corners, add an intermediate point anywhere on the border to modify it. After selecting the ‘Finish’ button, you can also change the name and type of the zone.

Your boat’s polar determines all routing calculations. It represents your boat’s performance depending on wind speed and angle.
The application supports files in the .pol format (also used by Weather4D, SailGrib, Adrena, and others).

To choose your boat’s polar from the library:

1. Go to the “My Boat” tab.
2. Click on the selected Polar.
3. A dialog opens with three tabs: Library, Imported, or iPolar.
4. In the “Library” tab, you’ll find a list of 495 polars for various well-known boats.

Most of these polars come from naval architects or ORC certificates.
To find your polar, you can:

• Scroll through the list.
• Use the search function — for example, type “3600” to find the polar for the Sun Fast 3600.

Once you’ve found your polar, select it and it will be confirmed.

Comment importer une polaire?

The application can import polars in the .pol format.

To import your own polar:

1. Go to the “My Boat” tab, then tap the selected Polar.
2. Select the “Imported” tab.
3. Click on the “Import a Polar” button.
4. Choose your .pol polar file saved on your computer or smartphone.
5. Once imported, click on the polar to select it.
6. The polar is then validated.
   
   Advantage: If you are logged into your NavimetriX account, the imported polar is automatically synchronized across all your devices!
   
   

iPolar lets you create a polar in one minute based on your boat’s characteristics:

1. Go to the “My Boat” tab, then tap the selected Polar.
2. Select the “iPolar” tab, then click “Create”.
3. Enter the required information:
   • Polar name
   • Overall length
   • Displacement
   • Main sail area
   • Jib area
4. Optional information:
   • Waterline length
   • Symmetrical spinnaker area
   • Asymmetrical spinnaker area
5. Choose your parameters:
   • Sailing style: Cruising or Racing
   • Polar type: Routing or Performance
   • (For most users: Cruising + Routing)
6. Click “Calculate my polar”.
7. Select your newly created polar.

Note: The iPolar method was developed by KND, experts who work with the America’s Cup, TP52s, and IMOCAs — the best in their field!

Some polars are formatted as .CSV (Comma Separated Value) files, where the field separator is a comma or semicolon. This format is not supported in NavimetriX, unlike the .POL format where fields are separated by tabs — a format widely used in navigation applications. Therefore, you need to convert your .CSV file to .POL.

With Excel (Windows / macOS)

Open a new Excel sheet and select the menu: File > Import.

Choose “CSV File” and then select your polar file from the Finder.

Check the box Delimiters = “Semicolon”, then insert the data into the existing sheet.

Then save the file in “Text (Tab delimited)” format, which will create a .TXT text file.

Finally, rename the file by replacing the .TXT extension with .POL:

Your polar file is now ready to be imported.

With Numbers (macOS)

Open the .CSV file with Numbers:

Export the file to TSV:

Replace the file .TSV extension to .POL, that's all.

To compute a routing, you must first have:

• Selected your boat’s polar.
  • from the library of more than 495 boats,
  • by importing your own polar,
  • or by creating your monohull’s polar very easily.
    
    If that isn’t done yet, check one of these 3 FAQs using the links above.
    
• Created a route.
  If not yet, see the “Create a route” FAQ.
  
• Downloaded the weather forecasts along the route.
  If not yet, see the “Download a GRIB” FAQ.

Once these 3 steps are done, you can compute a routing by pressing the “Compute routing” button.

Remember: a routing is only useful if it’s correctly calibrated and you understand the computed result. Doing a single run and treating it like a train timetable will, at best, lead to disappointment.
We therefore recommend this approach:

• Load the weather, try to understand it and especially the risks,
• always start simple:
  • a route that isn’t too complex, so the solver can “breathe”,
  • route with wind only,
  • no constraints on wind or sea state,
• add currents and waves only if needed,
• for thorough users, study routing stability by varying:
  • the wind GRIB speed percentage,
  • the polar efficiency percentage,
• run again with another weather model,
• synthesize, understand possible deviations and how you’d react,
• repeat every 12 hours…

1️⃣ Compute a routing

Click the “+” button, then select “Compute a routing”. A screen titled Routing opens.

You can choose three forecast models:

• a wind model,
• a current model,
• a wave model.

To begin, select only a wind forecast file.
We recommend setting the wind factor to 115%. This means taking 115% of the wind speed from the GRIB, reflecting that GRIB wind speeds are often lower than reality.

In a second step, following our recommendations, select a current model and a wave model.

2️⃣ Set the departure date and time

Click the date to open the calendar and select your departure date. Click OK.
Click the time to open hour/minute selection, then also validate with OK.

3️⃣ Choose the route

Select the route you just created.

4️⃣ Other settings

These are less frequently modified, but here are the main parameters at a glance.

- Adjusting the boat polar

• Polar
  See the “Choose your polar” FAQ.
  
• Polar efficiency for winds below 10 kn
  Most of the time, speed polars are theoretical and optimistic. If in doubt, set about 80% for a cruising boat.
  
• Polar efficiency for winds above 20 kn
  Similarly, polars are often optimistic. If in doubt, set about 90% for a cruising boat.
  For wind speeds between 10 and 20 kn, the app linearly interpolates between the two efficiency values to keep the polar “continuous”.
  
• Night-time polar efficiency
  This can help if you reduce sail area at night (e.g., take a reef or drop the spinnaker). This multiplicative factor stacks with the two efficiency settings above. Leave 100% to start with.
  
• Minimum upwind true-wind angle
  Again, polars are often optimistic. This lets you “trim” the polar to a realistic angle. For example, a Sun Fast 3200’s theoretical polar might show optimal upwind at 36° TWA in 12 kn. In practice it’s more like 40–45°. We suggest 40° with crew, 45° single-handed or cruising.
  
• Maximum downwind angle
  For safety: to avoid accidental gybes, don’t sail dead downwind even if the polar suggests it. Set about 165°.

- Routing algorithm

• Isochron time step
  Sets the duration of isochrones. We strongly recommend leaving it on Auto.
  
• Sweep angle
  Search angle for optimal routes. The faster the boat, the higher you can set it (up to 360°). The default 240° is well-suited to cruising boats and is already higher than the 180° used by most routing software.
  
• Angular step
  The angle between each computed route segment.
  Leave 2° — that’s usually sufficient. You can go down to 1° for more precision (slower), or 5° on slower devices.
  
• Maximum duration
  By default, routing can span the entire GRIB forecast range (up to 16 days). You can limit it (e.g., 3, 5 or 7 days) to compare optimal routes and assess stability. Thanks to a display trick in NavimetriX, this is almost unnecessary.

- Using the engine

• Allow engine
  Check to enable this mode.
  
• Start engine below
  Sailing speed below which the engine is started.
  
• Engine speed
  Speed once the engine is running.

- Special zones

• Avoid restricted zones
  Check to make the routing avoid these zones.
  These zones can include:
  • Traffic Separation Schemes (TSS),
  • wind farms,
  • shoal/shallow areas.
    
    Note: initially, these zones cannot be created or edited. This will come in a future update.

- Constant wind

Useful for studying, for example, the effect of current in a bay. It freezes the wind (e.g., as measured at the masthead) to understand the current’s influence on the optimal route.

• Constant wind
  Check to enable the mode.
  
• Constant wind speed
  Probably the value measured by your anemometer.
  
• Constant wind direction
  Probably the value measured by your wind vane.

- Wind and sea-state limits

Allows you to constrain the optimal route. Use with care, otherwise the routing may not converge. For example, don’t set a max downwind wind speed of 20 kn for an ocean passage.

• Heave-to beyond the limit
  Sets boat speed to 0 kn when a wind or sea-state limit is exceeded.
  Most routing software uses a “hard” constraint: you never go through that area once the limit is reached. That can be a bit silly: if a limit is exceeded for 3 hours during a long passage, it’s probably wiser to heave-to for 3 hours than to add hundreds of miles or days to the route.
  
• Maximum wind upwind
  Wind speed above which the constraint applies for angles from upwind to beam reach.
  
• Maximum wind downwind
  Wind speed above which the constraint applies for angles from beam reach to dead downwind.
  
• Maximum wave height
  Maximum “Total sea” height above which the constraint applies.
  

- Influence of cross sea

We define a cross sea when the angle between total sea direction and wind sea direction is between 45° and 135°. If the total sea height is high enough, the boat is significantly slowed. You can set the slowdown parameters here.

• Minimum height for a cross sea
  Minimum total sea height.
• Polar efficiency in cross sea
  Multiplicative factor to be combined with the other polar efficiency parameters.

- Reset parameters

It’s easy to get a bit lost among all these settings. The default values were chosen carefully. Press this button to restore them.

Once the routing is computed, the optimal route is shown on the chart together with the isochrone curves. These curves represent the positions that can be reached at successive time intervals from the start point.

You can move the boat along the route in two ways:

• by dragging the timeline,
• or by tapping directly on the routing at the desired location.

At each intersection between the optimal route and an isochrone, a wind barb is drawn. It indicates the strength and direction of the wind at the moment the boat reaches that position. This is the average wind speed on the isochrone, i.e., the average true wind speed (TWS) used for the routing calculation, which is therefore interpolated geographically and temporally. This is the value found in the routing table. If you are routing with a current, a current arrow will also be drawn according to the same principle as the wind.

Routing list

Open the lists panel and select the Routing tab. This tab lists all computed routings.

For each routing you’ll see:

• The routing name, shown in a specific color (matching the route color on the chart).
• Departure and arrival times.
• The total duration of the routing.
• The route length and the increase vs. great-circle distance (i.e., the shortest path between start and finish).
• The calculation timestamp.
• A round button to open the routing table.
• An eye icon to show/hide the routing on the map.

The routing table and its tabs

Click the orange button to open the routing table. It contains four tabs, each presenting a different facet of the computation.

• Routing tab
  • Shows, for each isochrone, the boat parameters at that time: speed, wind angle, position, etc.
• Statistics tab
  • Displays the distribution of speeds and wind angles encountered during the routing.
  • Helps you see whether you’ll sail mostly upwind or downwind, and assess the average wind strength.
• AI Briefing tab
  • Automatically generates a weather briefing using our AI.
  • When you click Generate AI Briefing, the routing data are sent to our AI server.
  • The AI returns a complete briefing with four sections:
    • 1. General situation & evolution
    • 2. Forecast along the route
    • 3. Routing analysis
    • 4. Weather risks
    • It also includes links to synoptic charts and to the Météo-France bulletin.
  • The AI Briefing is a Premium feature. Generation uses AI servers billed per use. Each Premium subscriber has a credit of 300 AI briefings per year, calculated on a rolling 365-day window.
  • ⚠️ Warning: this briefing is generated automatically by artificial intelligence. It may contain inaccuracies or errors. Always consult official forecasts and exercise sound judgment and good seamanship in your decisions. The skipper remains solely responsible for the safety of the vessel and crew.
• Input tab
  • Summarizes all parameters used for the computation: weather models, coefficients, constraints, and departure settings.

A pivot point is a location you want the routing to pass through.
It’s a very useful way to quickly compare routing options.
For example, in this case we’ll check whether it’s better to pass inside or outside the Traffic Separation Scheme (TSS) off Cape Finisterre — a very common situation when sailing from the French Atlantic coast toward Madeira or the Canary Islands.

To perform a routing with a pivot point, first make sure the isochrones of the desired routing are displayed on the map.

Show or hide isochrones

• Open the Routing list via the hamburger menu (☰).
• Click on the routing whose isochrones you want to display.
• A small orange bar appears to the left of the selected routing: the isochrones are now visible on the map.
• To hide them, click again on the same routing.

Create a routing with a pivot point on a phone

• Display the isochrones of the existing routing.
• Move the map — a yellow route automatically appears toward the center of the screen. It represents the optimal route to the currently selected point on an isochrone.
• If you want to force the route to pass through that point, press the + button and select “Route from this point” in the menu.
• A new routing is then computed starting from the selected pivot point.

Create a routing with a pivot point on a computer

• Display the isochrones of the existing routing.
• Move the mouse — a yellow route automatically appears toward the cursor position. It represents the optimal route to the currently selected point on an isochrone.
• If you want to force the route through that point, right-click on it and choose “Route from this point” from the context menu.
• A new routing is then computed starting from the selected pivot point.

First you have to verify that Isochrones are checked in the Display section of layers menu:

Then simply tap/click on the name of the routing in the sidebar:

When isochrones are displayed, you can use a pivot point.

You can display simulated navigation data all along the routing.

When isochrones are displayed, data labels in the same colour as the routing boat allow you to track progress along the route. In addition, clicking/tapping on each label displays the data graph from the start to the end of the route.

To scroll the boat along the route, a weather model must be displayed to activate the timeline.

A routing table is generated automatically and appears as an icon next to the route. Simply tap/click on the icon to display it.

Principle:

An isochronous line is the representation of phenomena known as “isochrones,” i.e., phenomena that have the same time duration.

In maritime routing, isochrones are lines connecting the different distances that can be traveled during a defined period of time, the “step” of the isochrones, in a geographical space — for us, the Earth — based on the polar target speeds of a sailboat.

To connect point A (start) to point B (arrival), the routing will therefore use the speed polar curve and relate it, through iterative calculation, to the average wind data (speed and direction) and current data (speed and direction), taking into account constraints, and multiplying the isochrones along the theoretical route connecting A to B.

How does it work?

The routing algorithm will scan a predetermined search angle, from 180° up to 360°, around the route and proceed with an iteration by calculating a large number of possible routes — this number depends on the search angle/angle step — on the time step defining the isochrones.

Definitions:

• Sweep angle (or search angle)

From 180° up to 360°, this is the opening angle of the geographical search field in which the isochrones will develop. The default setting is 240°. The chosen opening must take into account the geographical environment of the direct route to the destination point (position of the coastline bordering the route, passage through islands, aso). If the angle is to much open, it may cause divergent routing, too closed the routing may not be able to develop.

• Angle step

Angular steps in the search angle range, from 1° to 15°, default 2°. This is the calculation angle from each point selected on each isochrone. With a search angle of 240° and an angular step of 2°, 120 routes will be calculated from each point selected on each isochrone. The smaller the angle, the more computing power is required.

• Isochrone duration

This is the time between two isochrones. From “auto” by default, up to 360 minutes in 5-minute increments. It must be set according to the distance to be traveled, because the shorter the time step, the greater the accuracy, but the more computing power is required. The “auto” mode lets the program choose the time step based on the length of the leg.

From each isochrone point, the calculation is restarted until the next isochrone and so on until an “optimal path” from the starting point to the destination is obtained.

• Pivot point

On each isochrone, a blue dot shows the shortest distance to the destination. One of these points can be used as a “pivot point” to refine/correct the routing.

Other settings can be used by the developer to fine-tune their routing algorithms for performance optimization.

Ensemble routing may seem impressive: 31 route calculations in a single operation! In practice, it is as easy as a conventional routing. Here is how to do it, step by step.

Step 1: Download the GEFS model

• Open the GRIB file download menu.
• Select:
  • Type: Ensemble
  • Coverage: Global
  • GEFS 0.50° model (ensemble)
• Choose the desired time period
• Press: Download GRIB

The average GRIB file downloads like any other model; you don't need to do anything special.

Step 2: Configure and launch routing

Open the routing window and configure your routing as usual: starting point, destination, ship's polar curve, start date and time, etc.

NavimetriX automatically detects that you are using a GEFS model. The calculation button changes to display “Calculate ensemble routing.”

Start routing: NavimetriX handles everything!

1. Download the control run (gec00) and calculate its optimal route.
2. Download and calculate the 30 perturbed members, one by one.
3. Combine the results and display them on the chart.

The whole process is fully automated. Downloading each member takes only a few seconds, and route calculation is very fast. You can follow the progress in real time and see the routes appear one by one on the chart.

Step 3: Track progress

A compact progress panel appears at the bottom right of the screen. It displays the following in real time:

• Current phase: downloading or calculating
• Current member in progress: “Member 12/30”
• A progress bar for downloads

You can cancel the operation at any time if necessary.

How to interpret the results on the chart

Once the calculation is complete, the chart displays two key elements:

"Spaghetti" routes

Each member is represented by a distinct colored line (the colors are distributed across the entire spectrum to differentiate them clearly). Together, they form a bundle of routes — hence the nickname “spaghetti.” At a glance, you can see:

• Closely spaced routes = high confidence. Regardless of the weather scenario, the optimal route passes through the same location.
• Widely spaced routes = high uncertainty. The optimal route depends heavily on actual weather developments.
• Two distinct groups = two possible weather scenarios, with fundamentally different route strategies.

When the “spaghetti” routes converge, outside of waypoints, confidence is high.

The confidence corridor

Overlaid on top, a semi-transparent green corridor represents the range of ±1 standard deviation. Statistically, approximately 68% of routes fall within this corridor. The 20% of members furthest from the mean are automatically excluded from the calculation to prevent extreme scenarios from distorting the visualization.

The corridor gives you an immediate reading:

• Narrow corridor = reliable route, little variability between scenarios.
• Wide corridor = high uncertainty, the optimal passage zone is vast.
• Corridor gradually widening = confidence decreases over time (typical beyond 4-5 days).

Interpreting statistics

The “Ensemble” tab of the routing table provides a detailed analysis of the 31 scenarios:

• Members who reached the destination: what percentage of the 31 scenarios allowed the destination to be reached? If only 60% reached it, this is a warning sign.
• Distribution of durations: minimum, maximum, average, and median duration. A large min-max spread means that timing is very uncertain.
• Times Arrival (ETA): the earliest and latest, to plan your arrival at the port.
• Control run vs. ensemble average: if the control is significantly faster than the average, the “ideal” forecast is probably optimistic.
• Histogram: visualization of the distribution of durations (or remaining distances if few members reach the finish).

Helpful tips

When should you use ensemble routing?

• Crossings lasting more than 72 hours: uncertainty increases over time, so ensemble routing makes perfect sense.
• Unstable weather conditions: passing fronts, developing low-pressure systems, changing wind patterns.
• Go/no-go decision-making: before a departure, ensemble routing helps you objectively assess the level of risk.
• Medium- and long-term planning: for a crossing lasting more than 5-7 days, observe the daily evolution of member convergence.

Best practices for reading:

• Don't look for “the best route” among the 31 — look for the area of consensus.
• Use the time slider to see how the routes diverge over time: the first few days are often close, then the gap widens.
• Rerun the ensemble routing when new GEFS data becomes available (every 6 hours) to see if confidence increases or decreases.
• Combine with the spread of wind and pressure displayed on the chart to identify areas of high uncertainty.

Ensemble routing in NavimetriX transforms an analysis that was traditionally reserved for experts into a visual and intuitive tool. With a single click, you can switch from a single forecast to a comprehensive view of all possible options, allowing you to navigate with confidence, even when the weather is not.

———

See also: What is an ensemble weather model...

NavimetriX allows you to select multiple atmospheric models for routing calculations. The principle is to combine multiple resolutions on a given route. This is particularly useful for offshore voyages.

How it works

Multi-GRIB routing works as follows: when several wind GRIB files are added, the application automatically selects the best GRIB for each point and each moment of the calculation, based on three priority criteria:

• The finest resolution first (a GRIB at 0.025° will take priority over a GRIB at 0.25°).
• At equal resolution, the most recent run is preferred.
• At equal resolution and run, the most recently downloaded file is used.

We therefore do not “mix” models, which would not make sense, but “chain” them according to the distance to be covered and the coverage of each model. The multi-GRIB option only works for wind models.

An example:

Let's consider a crossing of the Bay of Biscay, departing from Lorient and arriving in La Coruña. You can use an Arome 0.025° model for the departure, and an ARPEGE Europe 0.1° or ICON Europe 0.0625° model to take over if Arome expires before your arrival. This allows you to calculate a single route instead of two successive routes.

Implementation

After downloading the GRIB files needed to cover (largely) your sailing area and activating your route:

Tap/click on the quick action icon and select “Calculate a route.”

• Select an “Atmospheric” wind model.
• Tap the small + button to select a second wind model. The first one should be the one with the longest lifespan.
• If necessary, select a wave model from “Sea State”.
• If necessary, select a current model.
• Choose your departure date (note: not too far in the future).
• Check that the route is displayed correctly.
• Press the “Calculate Route” button.

What is it used for?

The principle is to obtain the best possible resolution at the start of a voyage in order to refine the routing, and only reduce the resolution over the long term.

If we consider a transatlantic crossing, typical use is as follows:

1. A high-resolution GRIB (e.g., Arome, Arpège) that covers your departure area with good accuracy but for a limited duration (24-48 hours).
2. A low-resolution but long-range GRIB (e.g., GFS, ECMWF IFS) that covers the entire route over several days.

At the start, the routing will use the high-resolution GRIB (because its grid is finer). As soon as the boat leaves the spatial or temporal coverage of this first GRIB, the calculation automatically switches to the second GRIB, which covers the rest of the route.

Notes

If only the first GRIB file appears to be used, this may be because both GRIB files cover the same geographical area: in this case, the file with the highest resolution will always take priority across the entire common area.

If two models with the same resolution are used, for example ECMWF IFS 0.25° and GFS 0.25°, the most recent run will take priority when the calculation is launched (for example, GFS 06Z over ECMWF IFS 00Z).

Multi-GRIB is particularly useful when resolutions differ, for example Arpège Europe 0.1° for the coastal area combined with GFS 0.25° for the open sea.

For long distances, ensemble routing can also be used.

If you have deviated from your initial route, or if you have updated your GRIB files with a new run, you can calculate or recalculate a route underway at any time.

From the quick action button, select “Calculate routing”

With a route already displayed:

• Select the desired GRIB file models,
• Activate the “Start = Now from my position” option,
• Select the next waypoint in the drop-down list of waypoints on your route, according to your progress on the route.

Then simply start the calculation as you would for any other routing.

As seen in the Cap Martinique race, race instructions typically include details on Traffic Separation Schemes (TSS) that are prohibited along the course. Failure to comply with these zones results in severe penalties, as competitors’ track data serves as irrefutable proof.

It is therefore essential to plot the exact coordinates provided in these race instructions on the electronic charts, and not those entered by hand as one might do in Navimetrix. The app offers a feature to import ZOIs in text format for all TSS specified in the race instructions.

1. Copy the TSS coordinates from the Race Instructions

• Select the section of the race instructions containing the TSS description
• Select the text and copy it
• Open the left panel using the ≡ hamburger button
• Select the ZOIs tab
• Tap or click the “Import text” button at the bottom of the window

2. Import text

• Paste the copied content into the window that opens
• If necessary, format the text (there may be unnecessary blank lines)
• You can optionally shorten the name of each TSS in this window so that it appears more compact in the NavimetriX ZOIs window.

• Tap or click the “Parse Zones” button to check

• Tap/click on "Import x Zone(s)" button

You can now view the TSS in the ZOI list and on your chart.

A tip: if you previously created a TSS zone at the same location as the race instructions, disable its display or delete it to prevent its coordinates from interfering with those of the race instructions, which are the only official source.

Today, marine charting compatible with the app is provided exclusively by the Geogarage platform, where you must create an account and subscribe to one or more chart services depending on your sailing areas.

The charts available come from the official digital data of many international hydrographic offices such as the SHOM, UKHO, NOAA, and others.

Currently, about thirty publishers are available, offering near-global coverage. These are raster charts divided into tiles, allowing smooth zooming between scales.

When you subscribe to a hydrographic service via Geogarage, you gain access to all the charts published by that hydrographic office.

For example, if you subscribe to the SHOM (Service Hydrographique et Océanographique de la Marine) charts, you will have access to all SHOM charts.

Thus, if you’re sailing from La Rochelle to Fort-de-France across the Atlantic, a single SHOM chart subscription is probably sufficient to cover your entire passage.

As a reference:

• a UKHO chart subscription costs around €70 per year
• a BSH chart subscription costs around €25 per year
• a NOAA chart subscription costs around €4 per year
• a SHOM chart subscription costs around €60 per year.

Below is an illustration showing the diversity of hydrographic services available through Geogarage:

• The Solent by the UKHO (United Kingdom);
• The Kiel region by the BSH (Germany);
• And finally, San Francisco Bay by the NOAA (United States).
• The Toulon harbor by the SHOM (France);

Select a hydrographic service to view the chart coverage included with that subscription.

Annual subscription prices (VAT included)

In the Settings of Navimetrix, under the Geogarage Charts menu, you need to log in by tapping the “Login” button and entering your Geogarage account credentials.

Once connected, select your subscribed chart service (for example UKHO) from the “Layer” dropdown list. The chart display updates instantly while connected to the internet.

Download

In the Settings of NavimetriX, under the Geogarage Charts section, tap “Add New Zone”, then define the geographical area to download by dragging the green corners of the grey rectangle.

The Area selection dropdown menu offers two zoom-level options for the maximum chart scale:

• 11 (Offshore) — covers a large area containing only small-scale charts (ocean routes, offshore charts).
• 18 (All) — includes all scales up to detailed large-scale charts (ports and anchorages). If the selected area is too large, a warning will appear.

Once confirmed, a countdown shows the preparation and download progress.

A green frame remains visible so you can add new adjacent download zones without overlap using the “Add a new area” button. Only downloaded charts are available for offline use.

Updating downloaded charts

The downloaded chart zones are listed by publisher in the Geogarage Charts drawer. A checkbox allows you to select them for the Delete or Refresh functions.

Whenever a chart update is published by the provider, the Refresh button next to each zone becomes active. You can update them individually or in bulk by checking multiple boxes and pressing “Refresh Selected”.

In order to rename a chart area, you have to do a long click/tap on its name. This will bring up the keyboard, allowing you to change the name:

Please note that unlike GRIBs, downloaded charts are not synchronized, and therefore neither is the name.

Display GPS data from your phone

While sailing, if you want to display your phone’s GPS data, open the app settings (gear icon in the top-right corner).

Go to the GPS & NMEA menu and make sure the GPS source is set to Internal.

Exit this menu, then open Instruments. Check the Visible box to show the instruments, and make sure the selected layout is GPS View.

Once your phone receives a GPS signal, the time of the last position, your speed over ground (SOG), and your course over ground (COG) will be displayed in the instrument bar.
You can scroll through the parameters to view your coordinates and POI data if you’ve selected a waypoint using the Go to function.

On phones, the default display is horizontal.

On tablets or computers, the layout automatically adjusts to a vertical view.

A driver matching the connected device must be installed in the operating system beforehand. These are usually Prolific or FTDI drivers, depending on the type of device connected.

Implementation

Open Settings by tapping on the gear icon, then select GPS & NMEA.

Select:

• GPS Source = Internal
• NMEA Protocol = SERIAL
• Serial Port = scroll down the menu and select the appropriate port (normally the default port is displayed).
• Baud rate = 4800 Bps by default.

Data stream should scroll in the lower window.

Tip: if the serial port does not work, open the drop-down menu and check if another port is available. If no port is available, the driver is probably not the right one.

You can display several types of icons on the chart: AIS targets, navigation aids (NavAids), SART (Search And Rescue) distress beacons, AIS targets via the Internet, and “in-situ” weather data stations.

AIS Targets, NavAids, SART

AIS Target over Internet

Weather station 'in-situ'

To know more, read our FAQ: How to display "in-situ" weather stations

NMEA activation is synchronized on all devices connected to the same Wi-Fi router (NMEA gateway, multiplexer, onboard router). Therefore, disabling NMEA on one device, such as your smartphone, disables NMEA on other devices in use, such as tablets or computers.

You have two options in the above case:

1. Disconnect your smartphone from the Wi-Fi router to continue using Navimetrix in Internal GPS mode. You will no longer receive the data stream and your position will be that of your smartphone.
   • If your NMEA router is simultaneously connected to the internet via a Cellular SIM card, you should not disable NMEA on your smartphone because synchronization also occurs via the internet.
   • Offshore, offline, you can disable NMEA unless your router is connected to a Starlink antenna.
2. Close NavimetriX on your smartphone.

On the chart, the course vector on the ground COG is represented by a red arrow. The magnetic heading line is represented by a green line. Both are variable in length.

Open the app settings by tapping on the ⚙︎ icon, then select the My Boat section.

• The length of the heading vector is defined in minutes of time, from 0 up to 300mn. In example, 30 minutes on course at a 6 knots speed displays a vector of 3 nautical miles. This vector varies depending on your speed. You can disable the arrowhead.
• The heading line is set by distance on the chart, from 0 up to 300 NM. In example 20 nautical miles.

Open the app settings and select ‘My boat’. The track settings are at the bottom of the list.

You are able to:

• Enable/disable the display
• Adjust the duration, from 0 up to 365 days
• Select track width display (pixels)
• Select track color
• Choose whether or not to display wind barbules on the track
• Choose whether or not to display current vectors on the track
• Adjust the frequency of the wind/current display
• Clear track
• Export the track (GPX/KML format)

Laylines are automatically displayed when you have activated a POI using the ‘Go to’ function and you need to tack or jibe to reach your target, upwind or downwind.

Definition

The layline is an ideal course on the water for reaching targets: marks or waypoints. It is an imaginary line that varies depending on the wind, current, and the sailboat's ability to sail upwind or downwind, as determined by its speed polar curve. The layline starts from the target, upwind or downwind, to indicate the course to follow and the point at which a boat must tack or jibe in order to reach the target as quickly as possible.

How it works

By convention, the green layline is the starboard tack, and the red layline is the port tack.

Following this guideline, the distance to be covered by following the best VMG (VMG Max), upwind or downwind, is the same; it is the optimal distance to be covered. If you move outside the laylines, the distance to be covered increases; if you sail within the layline, performance decreases. The angle and heading values vary dynamically with changes in the apparent wind speed and direction.

You can activate the instruments corresponding to the layline data:

• Layline distance: length of the layline before tacking
• Layline time: duration of the layline before tacking

You can send NMEA data to instruments to:

• Control an autopilot by activating navigation to a waypoint.
• Send data from your mobile device's internal sensors to external repeaters.
• Send data to NKE Multigraphic instruments.

In the Settings menu, select the GPS & NMEA option.

In order to be received by your instruments, the sentences must be transmitted via a bidirectional gateway or multiplexer, usually via Wi-Fi. To be processed, you must first check the sentences allowed by your instruments in their user manual (autopilot, chartplotter, repeater, etc.).

You can feed each of the 8 dynamic channels of the NKE Multigraphic from a list of sentences by scrolling down the menu for each channel.

Manual measurement

Using the action button, you can perform several measurements on the chart. Select ‘Add a new measure’ then move the endpoints. The vector displays the distance and true bearing.

To delete the measurement, tap/click on the data lable of the arrow.

The origin and/or end of the arrow may be magnetized on a POI. In this case, clear the measurement by tapping/clicking on the free end, and if both ends are magnetized on two POIs, simply drag one of the two ends to release and clear it.

Automatic measurement

From the Layers button, check the ‘Auto measure’ display option:

The measurement arrow is automatically displayed from your location toward the target in the centre of the screen. Simply move the chart under the target to the desired location. The distance vector is then displayed for a short time, giving you time to read the distance and true bearing. Each time the chart is moved under the target, the vector is reset.

You can disable the distance vector display by unchecking the ‘Auto measure’ box.

DEMO mode allows you to view a navigation routine with moving AIS targets. This gives you an idea of how the application works when you are "at home".

Open the settings and select the GPS & NMEA option. Select GPS source = NMEA.

In the ‘NMEA Protocol’ drop-down menu, select DEMO.

The window will then display a simulated routine allowing you to see NavimetriX in action while navigating, select AIS targets to display CPA prediction points, read target information in the side column list, view navigation data in the instruments, etc.

NavimetriX receives navigation data from your instruments via NMEA 0183 sentences. When multiple sentences can provide the same parameter, the app uses the highest-priority source available (1 = first choice). If that sentence isn't received, it falls back to the next priority.

By default, the target is placed in the center of the screen, allowing you to drag the map underneath it and use the zoom to position it at a specific location.

However, you can lock the target to other elements, or even disable it.

Tap/click on the layers button.

In the “Target” drop-down menu, select which element you want to lock the target to:

• Disabled (to remove the target from the screen)
• Screen center (to place it to its original location)
• GPS position (to place it on your boat)
• A POI

You can also lock the target onto a POI by editing it.

FAQ - NMEA0183 XDR Sentence (Transducers)

What is the XDR sentence?

The XDR (Transducer Measurement) sentence is a generic NMEA0183 sentence used to transmit measurements from various types of sensors (transducers). It allows multiple measurements to be grouped into a single sentence.

What is the general format of the XDR sentence?

$xxXDR,a,x.x,u,n,a,x.x,u,n,...*hh

Where for each transducer group:

• a: Transducer type (one letter)
• x.x: Measured value
• u: Unit of measurement (one letter)
• n: Transducer name (character string)

The checksum (*hh) is mandatory.

Which transducers are supported by NavimetriX?

1. Heel/Pitch

Example:

$IIXDR,A,5.2,D,PTCH*XX

This indicates a pitch angle of 5.2°.

2. Roll

Example:

$IIXDR,A,-1.1,D,ROLL*XX

This indicates a roll angle of -1.1°.

Combined example (Roll + Pitch):

$IIXDR,A,-1.1,D,ROLL,A,5.0,D,PTCH*74

3. Water Temperature

Examples:

$IIXDR,C,18.5,C,WATERTEMP*XX
  $IIXDR,C,65.3,F,WaterTemp*XX
  $IIXDR,C,291.65,K,water*XX

4. Air Temperature

Examples:

$IIXDR,C,22.0,C,AIRTEMP*XX
  $IIXDR,C,71.6,F,AirTemp*XX

Combined example (Water + Air):

$IIXDR,C,18.1,C,WATERTEMP,C,22.0,C,AIRTEMP*49

5. Barometric Pressure

Note: The value must be expressed in Bars (1 bar = 1000 hPa). NavimetriX automatically converts it to hPa.

Example:

$IIXDR,P,1.013,B,BARO*XX

This indicates a pressure of 1013 hPa.

How do I combine multiple measurements in a single sentence?

Transducer groups can be chained in the same XDR sentence (up to 10 transducers per sentence):

$IIXDR,A,-2.5,D,ROLL,A,3.1,D,PTCH,C,18.5,C,WATERTEMP,C,21.0,C,AIRTEMP,P,1.015,B,BARO*XX

Is the transducer name case-sensitive?

No. Transducer name recognition is not case-sensitive for temperatures and pressure:

• WATERTEMP, WaterTemp, watertemp → all recognized
• AIRTEMP, AirTemp, airtemp → all recognized
• BARO, Barometer, baro → all recognized

Exception: For roll and pitch, the names must be exactly ROLL and PTCH.

Which talker prefix should I use?

NavimetriX accepts all standard talker prefixes (II, GP, HC, etc.). The examples above use $II (Integrated Instrumentation), but $GP, $HC, or others are equally valid.

Summary of accepted formats

You can display a path on the screen showing the maximum cross track error that should not be exceeded.

In the NavimetriX Settings, select the “Alarms” function, set the XTE course deviation to the maximum desired distance on either side of the activated route to a waypoint, then activate the alarm. This instantly displays, depending the zoom level, the XTE zone delimited by red (port) and green (starboard) dotted lines:

In that example, the value “460m” creates a corridor of 920 meters, or about half a nautical mile. You can select the audible alarm that suits you from the “Sound” drop-down menu.

.Leaving the “corridor” triggers an audible and visual alarm that you can disable by tapping/clicking on “Acknowledge” button

If you do not see NMEA sentences scrolling in the NavimetriX NMEA console, this may be related to the limitations of the WiFi module integrated in the box, which is now end of life. This module is no longer fully compatible with certain devices, in particular the most recent mobile devices.

Check the box software version
Before performing any other action, it is essential to verify that your NKE WiFi box is running the latest internal software version. The currently available version is version 2.5. A box running an older version may experience WiFi connection issues.
You can check the version of your box directly on your MultiGraphic or Multi Display, or using the TopLink software. The software update must be performed using the TopLink software.

Download and install the TopLink software
Checking and updating the software of the NKE WiFi box is done using the TopLink software. This software runs only on Windows PCs. To download it, go to the NKE website, click on the hamburger menu at the top right, then access the Technical access section. From there, open the TopLink software page, download the program, and install it on your computer.

Update the NKE WiFi box
Once TopLink is installed and launched, connect to your NKE WiFi box and perform the update to version 2.5.

Case of recent Apple devices
On some Apple devices (iPhone or iPad) running iOS versions higher than iOS 17 (versions released from 2024 onwards), a WiFi security mechanism added by Apple prevents connection to the NKE WiFi box, even when the box is up to date.
In this case, the WiFi must be forced into open mode, without a password.
To do this, press and hold the Init button on the NKE WiFi box for exactly 8 seconds. It is important to respect this duration precisely; you will hear 8 beeps. This action forces the box WiFi into open mode (no password), allowing affected Apple devices to connect.
Finally, restart the box.

Once connected to the box WiFi, access to the NKE WiFi box should be restored and you should see the NMEA sentences in the NavimetriX console.

AIS targets over Internet come from the global AISHub network, to which NavimetriX is affiliated.

The use and handling of AIS targets over Internet is exactly the same as for AIS targets received on board using an AIS receiver that transmits NMEA data to the application. For more details, see:

How to display AIS targets? in this FAQ.

Open the Settings panel (gear button at the top right)

• Select the AIS option
• Enable AIS over Internet

Cautions:

AIS targets over Internet should be considered for informational purposes only. Time delays due to Internet transfer speeds make them unsuitable for navigational safety, whereas reception on board by a dedicated receiver is at VHF frequency in real time.

They are therefore represented by blue icons to differentiate them from green AIS targets icons received directly.

For more details, see: What do the icons displayed on the chart mean in this FAQ?

If there is no Wi-Fi or USB connection to the onboard instruments, you can use a Bluetooth GPS device such as the GNS3000 from GNS Electronics. The procedure is as follows:

1. Pairing the device:
   • Put your GPS receiver into “pairing” mode (refer to the user manual for specific instructions; this usually involves pressing and holding a button).
   • In Windows 11, go to Settings > Bluetooth & devices > Add a device.
   • Select Bluetooth, choose your GPS receiver from the list, and complete the pairing process.
2. Checking in Device Manager:
   • Once connected, Windows usually installs the driver automatically.
   • Right-click the Start button > Device Manager.
   • Expand the Ports (COM & LPT) section. Your GPS should appear as a USB or Bluetooth serial port (e.g., “Standard Serial over Bluetooth link” with a COM port number, such as COM3). Note this port number.
3. Using it with NavimetriX:
   • Navigation applications can read NMEA data from the COM port identified in the previous step.

You should see your location data appear. If your GPS isn't detected, make sure the manufacturer-specific drivers (e.g., Garmin, Globalsat, GNS) are installed for your Windows version.

If you have deviated from your initial route, or if you have updated your GRIB files with a new run, you can calculate or recalculate a route underway at any time.

From the quick action button, select “Calculate routing”

With a route already displayed:

• Select the desired GRIB file models,
• Activate the “Start = Now from my position” option,
• Select the next waypoint in the drop-down list of waypoints on your route, according to your progress on the route.

Then simply start the calculation as you would for any other routing.

Route tracking allows you to set the boat to automatically navigate through each point on a route. If you control your autopilot by sending it NMEA data (*), it will steer the boat by following the successive legs from one point to the next.

Start route tracking

1. First, display a previously created route.
2. Tap or click on the first waypoint from which you want to start tracking.
3. Select "Follow route, start here

Activating this feature displays a course deviation corridor, which you can define in Settings > My Boat > Cross-Track:

The cross-track corridor follows all points on the route:

Stop tracking

You can stop tracking or reset the cross-track at any time:

Cross-Track Alarm

You can enable an alarm if the boat leaves the cross-track corridor.

1. Select the Alarms section in the app’s Settings.
2. Set the width of the corridor on either side of the direct route.
3. Choose a sound from the drop-down menu.

————

(*) See: How to send NMEA data to instruments

A slider allows you to turn Navigation Mode on and off. The goal is to prevent mobile devices from draining their batteries unnecessarily when certain navigation functions are not in use, such as when running route simulations, analyzing weather data, etc.

Navigation Mode

When Navigation mode is turned off, the GPS updates the location only every 30 seconds instead of every second.

Of course, don’t forget to turn Navigation mode back on as soon as you set off.

GPS Accuracy Indicator

An arrow icon indicates the GPS status on mobile devices:

NMEA Data Alarm

An NMEA data reception alarm can be enabled to warn of data loss for a customizable period of time.

A drop-down menu allows you to select the appropriate sound alarm.

As seen in the Cap Martinique race, race instructions typically include details on Traffic Separation Schemes (TSS) that are prohibited along the course. Failure to comply with these zones results in severe penalties, as competitors’ track data serves as irrefutable proof.

It is therefore essential to plot the exact coordinates provided in these race instructions on the electronic charts, and not those entered by hand as one might do in Navimetrix. The app offers a feature to import ZOIs in text format for all TSS specified in the race instructions.

1. Copy the TSS coordinates from the Race Instructions

• Select the section of the race instructions containing the TSS description
• Select the text and copy it
• Open the left panel using the ≡ hamburger button
• Select the ZOIs tab
• Tap or click the “Import text” button at the bottom of the window

2. Import text

• Paste the copied content into the window that opens
• If necessary, format the text (there may be unnecessary blank lines)
• You can optionally shorten the name of each TSS in this window so that it appears more compact in the NavimetriX ZOIs window.

• Tap or click the “Parse Zones” button to check

• Tap/click on "Import x Zone(s)" button

You can now view the TSS in the ZOI list and on your chart.

A tip: if you previously created a TSS zone at the same location as the race instructions, disable its display or delete it to prevent its coordinates from interfering with those of the race instructions, which are the only official source.

NavimetriX includes a comprehensive MOB (Man Overboard) function, with drift tracking, search pattern and AIS integration. Here's how to use it.

1. Enable the MOB button

The MOB button is not displayed by default. To enable it:

• Go to Settings → Navigation → My Boat → MOB
• Enable the MOB Button option

The red MOB button then appears at the bottom left of the chart, in Navigation mode only.

2. Trigger MOB

To trigger MOB, press and hold the MOB button for 1.5 seconds. A progress ring fills around the button to indicate progress. This long-press action is intentional to prevent accidental activation.

A short tap simply displays a tooltip reminding you to hold the button.

3. What happens when MOB is triggered

As soon as MOB is activated, several actions are performed automatically:

• MOB marker: a point of interest is created at the boat's current GPS position (e.g. "MOB 14:32:58")
• Active waypoint: the MOB position is set as the Goto waypoint, with a route line to the MOB
• Auto zoom: the chart centres and zooms to the MOB position
• Timer: an elapsed time counter starts immediately (displayed in red)
• Drift tracking: drift calculation begins (see next section)

4. The MOB dashboard (HUD)

An information banner appears at the top of the chart with essential data:

• Elapsed time: displayed in large red format (MM:SS)
• Bearing (BRG): heading to steer towards the MOB position
• Distance: distance to the MOB (in nautical miles, or metres when < 0.1 NM)
• Drift data: estimated drift speed and direction
• Mode badge: indicates the data source (GRIB wind, current, AIS...)
• Search button: to show or hide the search pattern

5. Drift tracking

NavimetriX estimates the probable position of the person in the water taking into account:

• Wind: using GRIB data or onboard instruments. Leeway is calculated at 3% of the true wind speed with a 10° divergence, in accordance with international search and rescue standards.
• Current: using GRIB data, tidal atlas or onboard instruments.

On the chart, you will see:

• An orange drift line connecting the initial MOB position to the estimated position
• An orange circle around the estimated position, whose radius increases over time (growing uncertainty)

The estimated position is updated every 30 seconds and the Goto waypoint is automatically adjusted.

6. Search pattern

NavimetriX can display an expanding square search pattern, compliant with international search and rescue procedures (IAMSAR).

To display it, tap the "Search" button in the MOB banner. The pattern is centred on the estimated drift position (or on the initial MOB position if no drift data is available).

7. MAYDAY reminder

60 seconds after MOB activation, if the situation is not resolved, a yellow banner appears as a reminder to consider a MAYDAY call on VHF channel 16 (RYA recommendation).

8. AIS MOB integration

If an AIS MOB beacon (personal or SART type) is detected nearby, NavimetriX reacts automatically:

• An audible alarm sounds
• An alert dialogue displays the beacon's position
• MOB mode activates automatically if not already active
• The AIS position is tracked in real time (updated every 5 seconds)

If the AIS signal is lost, NavimetriX automatically switches to drift estimation mode after 60 seconds.

The mode badge in the MOB banner changes colour depending on the situation:

• Green: AIS MOB beacon detected and tracked
• Red: AIS MOB signal lost
• Orange: drift data available (wind/current)
• Grey: no drift data available

9. Cancel MOB

To cancel MOB mode, press and hold the "Hold to cancel MOB" text in the MOB banner for 1.5 seconds. A progress bar confirms the cancellation.

Cancelling deactivates tracking, removes the Goto waypoint and hides the MOB banner.

10. Practical tips

• Enable the MOB button before heading out to sea in the settings, so it is immediately accessible in an emergency
• Load a GRIB file for your sailing area: GRIB wind and current data significantly improve drift calculation accuracy
• Equip yourself with an AIS MOB beacon: it provides real-time tracking of the person in the water, far more accurate than drift estimation
• The MOB button only appears in Navigation mode with an active GPS position

What is Race Tracking?

Race Tracking allows you to follow offshore sailing races in real-time directly on the NavimetriX chart. You can import race definitions, download position reports automatically or manually, and view rankings based on distance to finish.

What file formats are supported?

Race Tracking supports the Adrena format, which is the standard used by most offshore race organizers:

• .dcc files - Race definition with competitor list, classes, IRC ratings, and download configuration
• POSADRENA files - Position reports with boat coordinates and timestamps

What is a .dcc file?

A .dcc file (Adrena competitor description) contains all the race information:

• Race name and date
• List of competitors with their boat name, class, skipper, and IRC rating (TCC)
• Display colors for each boat
• FTP or HTTP server configuration for automatic position downloads

Example entry for KORNOG2, a Pogo 12.50 racing in IRC Two class:

KORNOG2;IRC Two;1;3;1;;;8;;1.170;O;Gilles Colubi & Yvan Osselin;;;

Race organizers typically provide .dcc files on their website or via email before the race start.

What is the POSADRENA position format?

POSADRENA is the standard format for position reports. Each file contains the latest positions for all competitors:

POSADRENA
  1;8;25.1873N;19.0716W;01/13/26 14:00:01

The fields are: race ID; boat ID; latitude; longitude; timestamp.

Important: Coordinates use the Adrena format (degrees.minutes), not decimal degrees. For example, 25.1873N means 25° 18.73' N (not 25.1873°).

How do I import a race?

To import a race:

1. Go to Settings → Race Tracking
2. Tap Import Race (.dcc)
3. Select the .dcc file from your device
4. The race and all competitors will be imported

How do I download position reports?

There are three ways to get position updates:

1. Automatic download (FTP/HTTP)

If the .dcc file contains server configuration, enable Auto-download and set the polling interval. NavimetriX will automatically fetch new positions.

2. Direct URL download

Some tracking systems (like YB Tracking) provide a direct URL that always contains the latest positions. Enter this URL in the connection settings and tap Download Now. NavimetriX will fetch the file and filter out positions already in the database.

Example URL format: https://yb.tl/racename-adrena.txt

3. Manual import

Tap Import Positions and select one or more POSADRENA files from your device. You can select multiple files at once to import a full position history.

How do I view competitors on the chart?

Once positions are imported:

1. Open the Race List from the Race Tracking menu
2. Toggle visibility for individual boats or use Show All / Hide All
3. Competitors appear on the chart with their track history
4. Tap a boat icon to see details (position, speed, course)

How are rankings calculated?

Rankings are based on Distance To Finish (DTF):

• Select a route that represents the race course
• DTF is calculated as the distance from each boat's current position to the finish, following the remaining waypoints
• Boats are ranked by ascending DTF (lowest distance = leading)

To enable rankings:

1. Create a route matching the race course (or import the official route)
2. In Race Settings, select the route name
3. Enter the race start date and time (UTC)
4. Rankings become available in the Race List

How does IRC corrected time work?

IRC (International Rating Certificate) uses a Time Correction Coefficient (TCC) to handicap boats of different performance levels. This allows boats of different sizes and types to compete fairly.

The formula is: Corrected Time = Elapsed Time × TCC

For example, KORNOG2 has a TCC of 1.170. If the boat finishes in 10 days (240 hours):

• Elapsed time: 240 hours
• Corrected time: 240 × 1.170 = 280.8 hours

A TCC greater than 1 means the boat is "fast" and gets penalized. A TCC less than 1 means the boat is "slow" and gets a time bonus.

For boats still racing, NavimetriX estimates the corrected time based on current VMC (Velocity Made good on Course) to project the finish time.

Why don't I see any boats on the chart?

Check the following:

• Make sure you have imported position reports (not just the .dcc file)
• Check that boat visibility is enabled in the Race List
• Zoom and pan the chart to the race area (boats may be far from your current view)
• Verify the positions were imported successfully (check the position count in Race List)

Why are speeds showing as unrealistic values?

Speed is calculated from position history. Unrealistic values usually indicate:

• Wrong start date/time: Check that the race start datetime in settings matches the actual race start (UTC timezone)
• Insufficient positions: At least 2 positions are needed to calculate speed
• Position errors: Occasionally, tracking systems report erroneous positions

Can I edit competitor information?

Yes, tap on a competitor in the Race List to edit:

• Boat name, class, and skipper
• IRC rating (TCC)
• Display color
• Arrival status and time
• Retirement status

Changes are saved to the database. You can also export a modified .dcc file to share with others.

NMEA data streamed by an NMEA gateway, a multiplexer, or any other instrument broadcasting on a serial port via a USB connection is supported.

Prerequisites

Normally, direct transmission of the data stream to a serial port does not require a driver.

Setup

Open Settings by tapping the gear icon, then select GPS & NMEA. Once connected and data transmission enabled, select:

• GPS Source = NMEA
• NMEA Protocol = SERIAL

Press the “Scan NMEA Devices” button.

• Serial Port = the detected port should appear in the window.
• Baud Rate = 4800 bps by default.

The data stream should scroll in the lower window.