Where the data comes from
Everything below is open data. We ask for it from our own server, so your browser is not handed over to anyone, and we keep the answers cached for a while.
Base map
OpenFreeMap · OpenStreetMap ODbL
Coastline, harbours and settlements — drawn by the OSM community. Tiles are served by OpenFreeMap without any key.
Sea marks
OpenSeaMap ODbL
Buoys, lights, cardinal marks and harbour details, collected by sailors themselves.
Satellite imagery
Esri World Imagery Esri, Maxar, Earthstar Geographics
Useful for anchoring: in shallow water the sand shows light and the weed dark.
Depths
EMODnet Bathymetry CC BY 4.0
Depths for the European seas, about 100 m per cell. We colour them ourselves: their own styling shows only the 50 and 100 m contours, and in white — near the shore, where depth actually matters, it shows nothing.
Weather and sea state
Open-Meteo CC BY 4.0
Wind, gusts, waves, water temperature and currents; for dates beyond the forecast we use their archive of past years. Based on national weather services (DWD ICON, ECMWF, MeteoFrance and others).
Coastline for routing around land
OpenStreetMap land polygons ODbL
The same coastline, rasterised to about a hundred metres per cell. It is what lets the service take a leg around an island instead of straight over it.
Places and search
Nominatim · Overpass · OpenStreetMap ODbL
Searching for a marina or a bay, and the list of what is nearby: water, fuel, groceries, a pharmacy.
Place descriptions
Wikipedia CC BY-SA 4.0
A short article about the island or the town you are heading to.
Sun and moon
our own calculation no external service
Sunrise, sunset, civil twilight and the moon phase are computed on our side by the standard NOAA formulas — checked against Open-Meteo to within a minute.
None of this replaces official charts and pilot books. Depths and marks are for planning only: check the passage against the paper or the plotter before you sail it.