While commercial nautical chart providers often allow weeks to pass between the release of new BSH data and its availability to end users, developer Adam Lucke has created an automated system that renders the open data published weekly by the BSH directly into a web-based nautical chart. The project for a free online nautical chart began as a hobby, as Lucke explains in an interview with Christian Sauerbeck from Yachtschule Eichler: "I looked to see if this data was freely available as part of open data - and it is indeed available."
Official map data at first hand
The free online nautical chart is based on the same database used by commercial providers and ECDIS systems for commercial shipping. The key difference: freenauticalchart.net eliminates the intermediate steps of commercial processing. Lucke uses the open source software QGIS to visualise the BSH raw data in the familiar nautical chart style - with all the familiar symbols, depths and buoys. The result is a complete, up-to-date nautical chart in the browser, whose update date is displayed at the bottom left of the page.
Unlike OpenSeaMap, which relies on crowdsourcing and where users enter tonnes and objects manually, the online nautical chart uses primary data from the authorities. This significantly increases reliability, especially for in-depth information, which is almost impossible to capture in the crowdsourcing model.
Classic navigation meets digital technology
A special feature of the free online nautical chart is the integrated plotting tools, which combine classic paper chart navigation with digital means. Users can enter bearings directly on the chart and determine the ship's location manually. They can also draw current triangles and perform dead reckoning - all with a click or touch. This allows classic chart work and electronic navigation to be combined without having to rely on GPS.
The toolbar offers, among other things:
- Route creation
- Bearing (right and wrong)
- Distance measurement
- Bearing with distance (radar fix)
- Sailing direction finding
- Coupling point
- Current triangle
Particularly practical: all tools also work on tablets, where they can be operated by touch - ideal for single-handed sailors or when sailing with a small crew who don't have to constantly go down to the chart table.
Integrated tide forecast and tidal stream atlas
Freenauticalchart.net integrates the tide forecast points of the BSH directly into the free online nautical chart. A click on a forecast point shows the tidal curve with high and low tide times. In addition, the BSH tidal current atlas can be displayed as an overlay - with current arrows, speeds at neap and spring times and directional information. A slider can be used to switch between the hours before and after high tide on Heligoland in order to check the current conditions along the planned route.
This integration eliminates the need to constantly switch between different sources of information: Nautical chart, tide calendar, current atlas and route planning all come together in one tool.
Can be used offline as an app, with or without GPS
The system can be installed as a Progressive Web App (PWA) on a smartphone or tablet. Installation takes place via the browser menu ("Add to home screen" or "Install"). In app mode, all previously viewed chart areas and tide forecasts are saved in the cache and remain available even without an internet connection. The app then shows additional functions such as GPS tracking with COG vector (ten minutes ahead), course over ground, speed over ground and a night mode with inverted brightness values.
Print function and export for other programmes
For practice purposes or as a backup, map sections of the online nautical chart can be printed directly from the browser on A4 or A3 - including the map border with coordinates and scale. If you want to use the maps in other programmes, you can find download packages for OsmAnd, AvNav and OpenCPN on the project page.
In addition to German waters, the free online nautical chart also covers the Dutch Wadden Sea and the area around Zeeland. Further regions are not planned, as the project is limited to the waters provided as open data by the BSH and the Dutch authorities.
Limits and exclusion of liability
Freenauticalchart.net is intended as a planning tool and navigation aid, but does not replace the obligation to carry up-to-date paper charts in accordance with the German Ship Safety Ordinance. The Notices to Mariners (BfS) also remain mandatory - they contain short-term changes that have not yet been incorporated into the weekly BSH updates. In addition, the up-to-dateness of the depth data depends on the last survey, which can sometimes be months ago in the Wadden Sea.
Despite these limitations, the free online nautical chart offers considerable added value for trip planning, training and as backup navigation, especially as it works independently of commercial providers and their subscription models. Further information on freenauticalchart.net.
Technical data
- Map coverage: German waters (BSH), Netherlands (Waddenzee, Zeeland)
- Update: Weekly automatic (after BSH updates)
- Data source: BSH Open Data, Dutch authorities
- Representation: QGIS-rendered, nautical chart style according to IHO standards
- Card edge: With coordinates and scale (like paper map)
- Utilisation: Free of charge, without registration
Functions:
- Route planning with waypoints (course/distance)
- Tide forecast (BSH forecast points)
- Tidal current atlas (BSH data)
- Plotting tools (bearing, distance, fix, DR, current triangle)
- GPS tracking (only in app mode)
- Night mode (inverted brightness)
- Print function (A4/A3 with card edge)
- Download map image (PNG)
PWA app:
- Installation: Via browser menu (iOS/Android)
- Offline mode: map areas are cached
- GPS tracking: With COG vector (10 min ahead)
- COG/SOG display
Export:
- OsmAnd (card package)
- AvNav (map package)
- OpenCPN (card package)
More on the topic:
Hauke Schmidt
Test & Technology editor
