Question 1

What Global Atmospheric Models are available?

Henri · Accepted Answer

ECMWF IFS 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 28 km to 111 km
Forecasts up to 10 days
👉 A key reference for offshore navigation. Prefer the high-resolution version (0.25°) with a good connection, or a lighter version (0.4° or 1°) when bandwidth is limited.

GFS 0.25° (28 km), 0.5° (56 km), 1° (111 km), 2° (222 km)
Global model from NOAA (United States). Available in multiple resolutions: the finer the grid, the heavier but more accurate the file.
Resolution: from 28 km to 222 km
Forecasts up to 16 days
👉 A key reference for offshore sailing. Prefer the fine version (0.25°) with a good connection, or a lighter version (1° or 2°) when bandwidth is limited. Very useful for comparison with the ECMWF IFS before a long passage, especially in the Atlantic or Mediterranean.

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.

Question 2

What Global Atmospheric Models are available?

Henri · Accepted Answer

ECMWF IFS 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 28 km to 111 km
Forecasts up to 10 days
👉 A key reference for offshore navigation. Prefer the high-resolution version (0.25°) with a good connection, or a lighter version (0.4° or 1°) when bandwidth is limited.

GFS 0.25° (28 km), 0.5° (56 km), 1° (111 km), 2° (222 km)
Global model from NOAA (United States). Available in multiple resolutions: the finer the grid, the heavier but more accurate the file.
Resolution: from 28 km to 222 km
Forecasts up to 16 days
👉 A key reference for offshore sailing. Prefer the fine version (0.25°) with a good connection, or a lighter version (1° or 2°) when bandwidth is limited. Very useful for comparison with the ECMWF IFS before a long passage, especially in the Atlantic or Mediterranean.

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.

Question 3

Glossary of marine terms in NavimetriX

Henri · Accepted Answer

📘 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.

Question 4

How do you calculate a routing with a pivot point?

Henri · Accepted Answer

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.

What Global Atmospheric Models are available?

What Global Atmospheric Models are available?

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What Global Atmospheric Models are available?

What Global Atmospheric Models are available?

Related Posts

Glossary of marine terms in NavimetriX

How do you calculate a routing with a pivot point?

What regional atmospheric models are available for Europe?

What are the wave patterns or sea conditions?

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