Navigation: Free BSH nautical charts - online or as a web app

While commercial providers of nautical charts often only provide updates for end users weeks after the release of new BSH data, developer Adam Lucke has developed an automated system that immediately converts the open data published weekly by the BSH into a web-based nautical chart. The project for a free online nautical chart started as a hobby, as Lucke reports in an interview with Christian Sauerbeck from Yachtschule Eichler: "I checked whether this data was freely available as open data - and it actually is."

Official map data at first hand

The free online nautical chart uses the same database as commercial providers and ECDIS systems in commercial shipping. The key difference is that freenauticalchart.net eliminates the intermediate steps of commercial processing. Lucke uses the open source software QGIS to display the raw data from the BSH in the familiar nautical chart style - including all known symbols, depths and tonnes. This creates a complete, up-to-date nautical chart directly in the browser; the respective 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 map work meets digital technology

The integrated plotting tools are a special feature of the free online nautical chart. They combine classic navigation on paper charts with the advantages of digital functions. Users can enter bearings directly on the chart and determine the ship's location manually. In addition, current triangles can be drawn and dead reckoning can be carried out - simply by clicking or touching.

This allows traditional map work and electronic navigation to interact seamlessly, even 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 is carried out 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: https://freenauticalchart.net

Technical data:

• Chart coverage: German waters (BSH), Netherlands (Waddenzee, Zeeland)
• Update: Weekly automatic (after BSH updates)
• Data source: BSH Open Data, Dutch authorities
• Visualisation: QGIS-rendered, nautical chart style according to IHO standards
• Map border: With coordinates and scale (like paper map)
• Use: 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)

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• The best apps for navigation and safety
• Classic navigation - this is how it works