Wattenschipper.de: New free tool for cruise planning in the tidal area

Since December 2025, Philip Simon has been operating wattenschipper.de one of the most popular websites for lovers of the tidal areas on the German North Sea coast. Simon, a computer scientist with a professional background as a graphic designer and former print shop owner, has given the site a major visual and technical overhaul and added new functions. The most important of these is a free interactive nautical chart with many useful functions.

Tradition, extended in a modern way

Simon took over the portal from Peter Renken and Christoph Essing, who have probably spent thousands of volunteer hours since 2009 showing sailors a safe route to the most beautiful places in the mudflats. The new version went online in December 2025 after a visual and technical overhaul - still exclusively funded by donations. "I always combine the graphics with the programming," he explains his approach. "When something technical is implemented, it also has to look nice and work well for me."

The interactive nautical chart: multiple data sources in one view

"Even when I was planning my own trips, I wanted to have all the information I needed in the Wadden Sea on one map," says Simon, explaining how the map came about. He himself used to prepare his trips using, among other things, high-resolution satellite images, which often show the morphology of the seabed in more detail and more accurately than nautical charts can. In addition to this, tides, water level forecasts and weather also need to be taken into account for accurate planning: a tedious back and forth between different applications. Simon's idea was therefore to combine everything relevant in a single map viewt. The result is a nautical chart with various switchable information levels that can be activated via a menu.

Basis and extensions

Simon uses the nautical charts of Freenauticalchart.net. This is an initiative that continuously integrates freely available data from the BSH into a free nautical chart and makes it available to users free of charge. The BSH points out that the free nautical charts cannot replace commercial nautical charts, as only data that has not been specifically analysed and tested for safe navigation is used.

Nevertheless, they are ideally suited as a basis for a planning tool, provided they are supplemented with up-to-date, commercial nautical charts. The area map from freenauticalchart.net forms the base map, over which Simon places various layers: high-resolution aerial images, water level indicators, protected area boundaries and navigation marks. Simon is in contact with Adam Lucke, the operator of Free Nautical Charts. "We know each other and we also exchange a bit of information about who has found which sources of information," he says about the collaboration in the community.

Also interesting in connection with Freenauticalcharts:

Free nautical chart: use BSH data free of charge in browser or app

Is BSH pulling the emergency brake on Freenauticalchart?

Classification of the BSH creates clarity

The integrated aerial photographs are a particular highlight. They come from the state of Lower Saxony and are exceptionally detailed. "They really have such a high resolution that you can easily recognise larger stones or old substructures of tracks or jetties," explains Simon.

In practice, this means that sailors can check in advance of a tour where exactly the tideways are, what the topography of the mudflats is like, whether old harbour structures are still present or where there are flat sandy areas to fall dry. The combination with superimposed sea marks enables far more detailed planning than with conventional nautical charts alone. Simon also uses this function to identify new anchorages - to the west of the entrance to Juist, for example, where there is a long sheet pile wall and a large sandy area for good mooring, or to the east of Baltrum harbour, where five to six boats can regularly be seen on the aerial photos.

Water levels according to SKN and with tidal prediction

Another major simplification is the visualisation of water levels. The BSH outputs its data according to sea level zero, "but this reference value doesn't help you on the nautical chart," explains Simon. The Wattenschipper chart therefore shows the values according to sea chart zero (SKN). This allows sailors to see directly whether a high tidal flat is still or already passable.

A novelty: in addition to the official BSH gauges, the map also shows the water levels at the smaller gauges of the Waterways and Shipping Administration and supplements them with a combination of astronomical tide forecasts and meteorological forecasts. The data is updated regularly and displayed directly at the tide gauge stations on the map.

Protected area boundaries - more clarity, fewer myths

New rules have applied in the Wadden Sea since the North Sea Navigation Ordinance was issued in 2022. Protected areas have been extended or their status changed. Recreational boaters feared that travelling popular routes across the mudflats or anchoring and falling dry would hardly be possible any more. Philip Simon presented his project at boot Düsseldorf. "You notice time and again that people believe that you are no longer allowed to do anything in the Wadden Sea - no more sailing anywhere, no more falling dry anywhere," Simon reports on the assessment of many of his stand visitors.

In fact, this impression can arise when looking at the nautical chart. There, the boundaries of the protected areas are shown as dashed lines, but their total area is difficult to recognise. However, the reality is different, as shown by the "Protection zones" overlay that Simon has integrated into the Wadden Sea map: If you activate it, the General and Special Protection Areas are displayed in colour - transparently, so that the underlying map is still clearly visible. "If you activate the aerial photographs, for example, you can overlay the protected areas directly on top. Then you can immediately see the tideways and sandbanks and where you are allowed to lie," explains Simon. The colour overlay of the detailed aerial image makes the boundaries clear.

Navigation instructions for sailing yachts - a safety campaign

Also integrated into the map are navigational instructions for sometimes dangerous sea races. Simon has also dedicated a separate section of the website to this information. There is a long story behind this and a clear concern. Three years ago, Simon was stopped by the water police near Hooksiel. His paper chart was more than two years old. Although he had the latest electronic ENC charts for commercial shipping on three devices on board, he was still ordered to pay a fine.

In conversation with the water police officer, Simon discussed why these checks are carried out so rigorously. The reason: Accidents are known to occur very frequently in the sea galleys, sometimes on a monthly basis, especially near Norderney. "That's true. But the problem is not the nautical charts," says Simon. Rather, there is a lack of awareness of how dangerous the sea slips can be under certain conditions.

This resulted in a campaign, which is linked on the site as a red button. The page summarises the five most important points for safely navigating a tidal flat and is available in seven languages - with a QR code so that foreign guests, especially Dutch people who frequently visit the Wadden Sea in Lower Saxony, can quickly access the information. Simon created the content in consultation with various institutions and also offers it as a poster for harbour display cases.

The instructions are deliberately worded simply and with safety buffers. "For example, I write: 'mainly when the water is rising, ideally from two hours before high water'," explains Simon, because those who know their way around have more room for manoeuvre. "The point is that people who are not familiar with the area still have a safety buffer."

All information for good planning included

The map and website also contain other important information for comprehensive trip planning, including the sounding depths over the Wattenhochs, current water levels and wind and weather forecasts, which can even be used to create a weather routing. In addition, all 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 described, are still available. "All the routes described can be travelled without any problems, they are outside the special protection zones," assures Simon.

With all the good planning options: Simon is keen to emphasise that the Wattenschipper chart does not replace official nautical charts. "It is intended as a planning tool, but not primarily to be used as a navigation tool while sailing."

Simon explains the functions in a YouTube video: