40kn Sail RouterWeather routing for sailors
40kn Sail Router finds the fastest route for your boat through the forecast wind and currents — right in the browser, and offline at sea.
Built for real passages
Pick a start, a destination and a departure time. The router does the rest.
Fast isochrone routing
Using your boat’s polar and the forecast wind and currents, the router calculates how far you can sail in every direction per time step and extracts the fastest route.
How routing works ›19 forecast models
Global models (GFS, ECMWF) for the crossing plus high-resolution models for the coast: pick the forecast that fits your passage, or route with several and compare.
See the models ›Polars for almost 100 boats
Polars from ORC certificates for almost 100 boats are built in, with ORC’s permission. Use one of them or load your own polar file.
Set up your boat ›Compare routes
Route the same passage several ways and compare the results side by side on the map and in graphs: different forecast models, departure times, boat speeds by day and by night, and sailing-angle limits.
Planning a passage ›Works offline
Install it like an app, download the forecast for your sailing area in harbour, and route without a connection at sea.
Going offline ›Export to your plotter
Export the route as a GPX file and load it into your chartplotter or navigation app.
Reading the result ›Route right away — no GRIB downloads
No GRIB files to find, download and import first. 40kn Sail Router reads just the forecast your route needs, straight from the server, while it routes.
Only what the route needs
As the isochrones spread, the app fetches just the parts of the forecast they reach — not a whole ocean’s worth of GRIB data.
Computed on your device
No server queue, no account, and your routes stay on your device.
Fresh forecasts, ready to use
New model runs are published soon after each weather service releases them. Every model page shows when it last updated.
Ready to plan a passage?
No account, no install needed. Open it in any modern browser.