Navigate · Weather
Multi-model marine weather, routed for your boat.
I aggregate five public forecast models — GFS, ECMWF Open, ICON-EU, AROME, and CMEMS for wave state and currents — and serve them through a cache so you don't have to manage API keys for any of them. On top of that I run my own isochrone routing engine: it takes your boat's polars, your departure window, and the combined forecast, and tells you the fastest and safest route given the conditions.
Data sources
Open data, cached and ready.
The forecast models I use are all publicly licensed — NOAA, ECMWF Open Data, DWD, Météo-France, and Copernicus. I cache them so you don't manage keys. If you have a paid subscription with a premium provider, you can bring your own key and I'll promote it to priority one.
| Model | Provider | What it covers | Licence |
|---|---|---|---|
| GFS 0.25° | NOAA — National Oceanic and Atmospheric Administration | Global wind, pressure, precipitation, 16-day horizon | free / public domain |
| ECMWF Open | European Centre for Medium-Range Weather Forecasts | Global wind + waves, 10-day, higher resolution than GFS | CC-BY 4.0 |
| ICON-EU | DWD — Deutscher Wetterdienst | Europe + North Atlantic; 7km resolution, 5-day | free / CC-BY |
| AROME | Météo-France | Western Europe; 1.3km resolution, 42h | free / open licence |
| CMEMS waves + currents | Copernicus Marine Service | Global wave model, surface currents, sea state | free / EUPL |
| Premium providers | Your own subscription (Stormglass, Windy, and others) | Higher-resolution or value-added forecasts via your key | BYOK |
Isochrone routing
The routing engine, step by step.
Isochrone routing answers: "given where I am now and the forecast for the next five days, what is the fastest path to my destination?" Here's what actually happens.
Pull the forecast
The routing engine fetches the latest GRIB data from the cache — typically GFS plus ECMWF as a cross-check. Each grid cell has wind speed, wind direction, wave height, and current vectors at 3-hour intervals for the forecast horizon.
Project possible positions
Starting from your departure point and time, the engine calculates all reachable positions at 3-hour intervals using your boat's polars — the table of speed-at-wind-angle that describes how fast your hull goes on each point of sail. This produces a set of isochrones: curves of equal elapsed time.
Prune infeasible paths
Land, shallow water (below your draft plus 2m safety margin), and regulated areas the boat must not enter are removed from the solution space. Depth data comes from EMODnet for European waters and GEBCO globally.
Select the route
The engine traces back through the isochrone fan from the destination to the departure and produces the optimal path. You see the route on the chart with per-leg wind arrows, estimated time at each waypoint, and the departure window comparison — leave Wednesday 0600 versus Thursday 1200 versus Friday 0600.
Push to the chartplotter and passage planner
One tap sends the route to the chartplotter as the active route and to the passage planner for the pre-departure checklist. The same polar and weather data follows the route — there's nothing to copy across apps.
Roadmap
What's built and what's next.
Multi-model forecasts
GFS, ECMWF Open, ICON-EU, and CMEMS waves in one view. Wind overlays, gust contours, swell arrows, and current vectors. Boat-position-aware forecast strip — the next 72 hours at your current location, auto-updating.
Isochrone routing + BYOK
Full GRIB-based isochrone routing with your boat's polars. Departure window optimiser and route comparison. BYOK fall-through for paid forecast providers — bring your own key and it becomes priority one.
AI weather queries
The AI agent host can pull the same forecast via the platform's internal model context. Ask "should I leave Wednesday or wait until Friday?" and get an answer that factors in the actual forecast, your destination, and the route I've already computed.
See the weather and routing in the demo.
The demo includes the forecast overlay and the isochrone routing view. Or explore the passage planning page to see how weather integrates with the pre-departure workflow.