GPS boat speedometer and navigation for small boats. Under motor, paddle or oars. A Bluetooth BMS or a coulometer on the pack adds live values and range. Navigation * Set a destination on the map: straight line or a route along the waterways, with distance and estimated draw * Load map data onto the device, then route offline up to 600 km * Craft type, motorboat or canoe, decides which bans apply * Locks and weirs on the route, tap one for hours, phone and chamber size * Seamarks are tappable, speed signs show their number * Map north up or course up, marker and map glide Speed and trip * Large readout, km/h or knots, decimals configurable * Start and stop through a foreground service, keeps measuring with the screen off * Trip history with distance, times, Ah, Wh and Wh/km, GPX export and import * Satellite and GPS status, smoothing of the raw value Battery (Bluetooth LE) * Several packs, wiring single, parallel or series * Voltage, current, state of charge, remaining Ah, temperature, cells * Range and remaining time at the current speed, time-averaged * JBD and Redodo/LiTime/Power Queen verified on hardware, Daly and JK experimental * Coulometer with a Hall sensor for packs without Bluetooth, verified too * Charging mode with time to full and an alert at a chosen level Weather and safety * DWD rain radar, readings from the nearest station, wind direction * Weather warnings for thunderstorm and storm * Anchor watch with a drag alarm What the app talks to * Base map from OpenStreetMap, seamark overlay from tiles.openseamap.org * Waterway tiles for routing from boatspeedy.wozise.de, a server run by the author. The data comes from OpenStreetMap, the generator is open source (Glenn-Dandy/boatspeedy-mapdata) * Without matching tiles, routing asks the public Overpass servers * Weather and warnings from the Deutscher Wetterdienst, via maps.dwd.de and api.brightsky.dev * Update check at api.github.com, only when you tap it Free and open source, without Google Play Se