- Tradition, extended in a modern way
- The interactive nautical chart: multiple data sources in one view
- Basis and extensions
- Water levels according to SKN and with tidal prediction
- Protected area boundaries - more clarity, fewer myths
- Navigation instructions for sailing yachts - a safety campaign
- All information for good planning included
Since December 2025, Philip Simon has been operating wattenschipper.de one of the most popular portals for tidal areas on the German North Sea coast. The computer scientist, who has also worked professionally as a graphic designer and used to run a printing company, has completely redesigned the site, modernised it technically and added additional functions. The centrepiece is a free, interactive nautical chart with many practical tools.
Tradition, extended in a modern way
Simon took over the platform from Peter Renken and Christoph Essing. The two have probably invested thousands of volunteer hours since 2009 to show recreational boaters safe routes to attractive destinations in the mudflats. After a thorough visual and technical overhaul, the new version went online in December 2025 - still financed exclusively by donations. His claim: technology and design should go together. When something is programmed, he believes it should not only work, but also look good and be intuitive to use.
The interactive nautical chart: multiple data sources in one view
The idea for the map came from Simon's own practice. He wanted to see the information needed for planning a trip in the Wadden Sea bundled together on a map. In the past, he used high-resolution satellite images, among other things, because they often show changes in morphology more accurately and in greater detail than classic nautical charts. For precise planning, tides, water level forecasts and weather data are also added - until now often only with constant switching between several applications. This is exactly what needs to change: Everything relevant should come together in a single map view. The result is a nautical chart with various switchable levels that can be conveniently activated via a menu.
Basis and extensions
Simon uses the nautical charts from Freenauticalchart.net as a map basis. The project continuously processes freely available data from the BSH into a free nautical chart and makes it available to users free of charge. At the same time, the BSH points out that these free charts cannot replace commercial nautical charts because only data that has not been specifically analysed and checked for safe navigation is used.
Nevertheless, they are suitable as the basis for a planning tool - especially if they are supplemented with up-to-date commercial nautical charts as required. Simon adds additional layers to the basic chart from freenauticalchart.net, including high-resolution aerial images, water level indicators, boundaries of protected areas and navigation marks. He is in dialogue with Adam Lucke, the operator of Free Nautical Charts. The community shares sources and experiences about who has found and utilised which data.
Also interesting in connection with Freenauticalcharts:
In practice, this means that pleasure boaters can check in advance where tidal flats run, how the mudflats are shaped, whether old harbour structures still exist or where there are smooth sandy areas to fall dry. In combination with superimposed sea marks, planning becomes much more precise than with a nautical chart alone. Simon also uses this view to discover new anchorages - for example to the west of the entrance to Juist, where a long sheet pile wall and a large sandy area make for good mooring, or to the east of Baltrum harbour, where five to six boats can often be seen in the aerial photos.
Water levels according to SKN and with tidal prediction
The chart also makes things noticeably easier when it comes to water levels. The BSH publishes water levels in relation to sea level zero - a reference value that is only of limited use in the nautical chart for estimating water depths. The Wattenschipper chart therefore shows the values according to sea chart zero (SKN). This makes it possible to directly assess whether a high tidal flat is still navigable or is already becoming critical.
Another new feature is that, in addition to the official BSH gauges, the map also shows water levels at smaller gauges operated by the Waterways and Shipping Administration. These are supplemented by a combination of astronomical tide forecasts and meteorological forecasts. The data is updated regularly and displayed directly at the tide gauge locations on the map.
Protected area boundaries - more clarity, fewer myths
With the North Sea Navigation Ordinance of 2022, new rules apply in the Wadden Sea. Protected areas have been extended or their status changed. Many recreational boaters were concerned that popular tidal flat crossings or anchoring and falling dry would no longer be possible. Simon presented the project at boot Düsseldorf and reports that he often encountered this view there: many people believe that you are no longer allowed to do practically anything in the Wadden Sea - neither sail nor dry out.
This impression can be created by the visualisation of classic nautical charts: There, protected area boundaries are often only marked as dashed lines, making it difficult to recognise the actual extent of the area. This is precisely where the "Protection zones" overlay that Simon has integrated comes in. When it is activated, general and special protection areas appear in colour and are transparent so that the underlying map remains visible. If you combine this with aerial photos, for example, you can see tideways, sandbanks and the areas in which you are allowed to lie. This makes boundaries much clearer and reduces misunderstandings.
Navigation instructions for sailing yachts - a safety campaign
The map also contains sailing instructions for some of the more challenging sea races. Simon has also given this information its own section on the website. This was triggered by an incident three years ago: Simon was checked by the water police near Hooksiel and his paper chart was over two years old. Although he had up-to-date electronic ENC cards on three devices on board, he was ordered to pay a fine.
During the discussion, it became clear why such controls are strictly enforced: It is well known that accidents occur frequently in sea galleys, sometimes even monthly, especially in the Norderney area. However, Simon emphasises that the nautical charts are not the main problem. Rather, it is the lack of awareness of just how dangerous sea races can be under certain conditions.
From this, he developed a safety campaign that can be accessed via a red button on the website. The page summarises five key rules for safe navigation of a tidal flat, is available in seven languages and contains a QR code so that foreign visitors - especially Dutch people who frequently visit the Wadden Sea in Lower Saxony - can quickly access the information. The content was developed in consultation with several institutions and can also be used as a notice for harbour showcases.
The instructions are deliberately simple and contain safety reserves. Simon recommends, for example, that you should only navigate in the upper reaches when the water is rising, ideally from two hours before high tide. Although those with local knowledge often have more room for manoeuvre, this recommendation provides a sensible buffer for less experienced drivers.
All information for good planning included
For thorough trip planning, the map and website provide additional content, including sounding depths over Wadden highs, current water levels and wind and weather forecasts, which can even be used to create a weather routing. In addition, routes "across the meadow", i.e. across the mudflats, as well as places to anchor and dry out are described. These classic mudflat routes, which Renken and Essing had already documented, are still available. Simon emphasises that all the routes described can still be navigated without any problems, as they lie outside the special protection zones.
Despite the many possibilities, one point is important to him: The Wattenschipper chart does not replace official nautical charts. It is intended as a planning aid - not primarily as a navigation tool during the journey.
Simon explains the functions in a YouTube video:
Ursula Meer
Redakteurin Panorama und Reise
