FreeNauticalChart: The BSH gives its view – Interview with Thomas Dehling
Antonia von Lamezan
· 13.06.2026
YACHT: Mr Dehling, from the BSH’s point of view, what is the main problem with FreeNauticalChart?
Thomas Dehling: Free Nautical Chart isn’t a problem at all. The problem lay with us. We had a configuration error in our GeoSeaPortal, which meant that data was freely available that we are, strictly speaking, only supposed to distribute via our licence holders.
After all, there is a requirement from Brussels that public authorities must make their data publicly available as open data.
Yes, and we do this on a very large scale. In accordance with the Geodata Access Act, we make all kinds of geoinformation available – including depth data and other information contained in nautical charts. However, the nautical chart data itself – that is, what we refer to as Electronic Navigational Charts, which are mandatory for commercial shipping – is not covered by this. We supply this information to licence holders via our distribution channels.
Why aren’t they included? Isn’t all data supposed to be made public?
No, on the contrary – there are some that we are not at all allowed to make freely available. Under the Federal Budgetary Regulations, we are obliged to act in an economically sound manner. This means that we must sell our products – and these are actual products, not just data – in a secure manner and at a market-standard price. If I were to stop doing this, I would need a legal basis for it or an exemption from this regulation.
The quality-assured nautical chart information, into which we are investing even more effort – after all, we are ISO-certified in quality management – must be provided in such a way that it reaches the licensee in a quality-assured state.
How did this configuration error come about?
I can’t say in detail. But if you make data available that was actually only intended for licence holders, and there’s a link you know of that takes you to it – it wasn’t freely and publicly displayed, but it was findable. When we realised this, we rectified the situation. Since then, FreeNauticalChart and others have only been able to access the freely available data, provided they do not hold a licence with us.
So, does that mean Adam Lucke didn’t do anything wrong?
No, not at all. Mr Lucke has a brilliant A product capable of displaying tide tables or other information in a visually appealing way. Of course, he didn’t do anything wrong. It wasn’t his fault that this loophole existed. That was down to us. That’s why we had to rectify it as soon as we realised it.
Who says you had to correct that? Did that come from the Federal Ministry of Transport?
If I have a distribution channel for data and have to charge market rates, then I can’t simply give it away for free. At some point, the Federal Minister of Finance or the Federal Audit Office would ask me: ‘Why aren’t you managing federal funds in a cost-effective manner?’ Incidentally, the revenue does not go to the BSH, but directly to the Minister of Finance.
So the point is that a public authority needs to refinance itself?
We do not use this to fund our operations. As I said, the revenue goes directly to the Treasury. However, this represents only a very small proportion of the total costs incurred by hydrographic surveying. This is something we do as a public service. Taxpayers’ money is used for this purpose. That is why we make this information available as widely as possible – with the sole restriction that the nautical charts and electronic nautical charts we provide are subject to licence fees.
How does the licensing model work in practice?
Map producers – whether they produce printed or electronic maps – come to us. It depends on the volume, the areas covered and what they intend to use the data for. There is then a fee to be paid, after which you have unrestricted access to this data via a defined interface.
There is no limit to the number of licence holders who can obtain this. Therefore, this does not hinder the market, but rather facilitates it. We at BSH stay completely out of the recreational boat market. We used to produce recreational boat licences ourselves, but we haven’t done so for quite some time now.
When FreeNauticalChart was launched – did any commercial chart providers get in touch with you?
Not originally. When we realised this loophole existed – because it had come to light – we asked: ‘How did this happen?’ And then we sorted it out. Of course, we’re also thinking of our licence holders in the second instance, because I’d understand if they came to us and asked: ‘Why do we have to pay when others get it for free?’
The BSH has not only issued a warning, but has actually banned its use. ‘Not suitable’ has become ‘not permitted’. Why?
We have adopted the international wording. The standard international phrasing is ‘not to be used for navigation’. This is, incidentally, also the case in aviation with regard to aeronautical charts. When translated, this is actually a stricter formulation than ‘not suitable’. We must point out that the information provided via the WMS services does not constitute verified navigational data.
As a sailor, I’d say: I hardly care whether the buoy is positioned to within a metre or not. Navionics doesn’t guarantee anything either and excludes all liability. Why should you trust them any more than FreeNauticalChart?
Unlike in commercial shipping, there is no mandatory equipment requirement for the recreational boating sector. This has its advantages for the recreational boating sector, but of course it means that the responsibility lies more with the individual. They must be able to decide for themselves what to do and how reliable their equipment is. I fully understand that electronic nautical chart data makes navigation much easier than using paper charts.
However, it’s important to realise that the data can never be 100 per cent accurate. We carry out wreck surveys; we search very thoroughly for objects – but there’s always the possibility that there might still be a rock we haven’t spotted. You have to demonstrate sound seamanship. But there’s a difference between a buoy not being plotted exactly in the right place and depths not being accurately charted for navigational purposes.
Do depths really vary so much that safety is compromised? Or is it more a question of cost-effectiveness?
These are two different matters. One concerns how we organise the distribution channel and what we charge for the licences. The other aspect is that we provide this information for the safety of shipping in such a way that it can be relied upon. This includes ensuring that the depth data is analysed in accordance with nautical standards.
I have to ensure that the shallowest areas are included and that features such as underwater obstacles are recorded – in the correct location and up to date. The International Hydrographic Organisation requires a specific quality standard. To meet this, we very often have to carry out repeat surveys in German waters. The Waterways and Shipping Administration carries this out monthly on the main shipping routes, whilst we at the BSH do so across a wide area. In very shallow, sandy areas, depth changes of several metres are certainly possible within a short space of time.
They are updated weekly via the notices to mariners. But this information doesn’t appear on my printed paper chart.
That’s right. But it’s very different from topographical maps on land. We have to ensure that our official nautical charts are always up to date. If the weekly update cycle, together with the notices to mariners, is no longer sufficient, the shipping industry is informed via the warning service. If one of our wreck-search vessels discovers a new wreck and the situation is urgent, the information is passed on immediately to vessels via the warning message.
Is FreeNauticalChart really about safety, or is it actually about revenue?
It really is all about safety. The second aspect for licence holders is that we know exactly who is receiving our products. That means I know who accessed which data and when. If something happens – someone runs aground or there’s an accident – I can trace it back: where did the problem lie? Was the nautical chart data incorrect or out of date? Thanks to our quality management system, we can trace this right back to the individual survey vessel mission.
If I do this via a WMS service, where anyone can download anything at any time and where we cannot guarantee which data was used at what point, then I can no longer guarantee this. This also provides greater safety for sailors and recreational boaters.
Is there a clear legal framework setting out which data must be classified as open data and which must not?
Yes, actually it’s quite clear. Nautical chart data and paper nautical charts are not freely available, but must be sold at a market rate. We are legally bound by clear provisions in this regard. The Geodata Access Act has been in place for several years now, and this is standard practice in other European countries as well. Even the Dutch do not make everything freely available for navigational purposes.
As a sailor, what is the difference between an official BSH chart and FreeNauticalChart? Is it really less reliable?
Yes, less reliable. The data used by FreeNauticalChart or others with WMS data is not of the same quality as the data we provide to licence holders. We don’t do this to put others at a disadvantage, but rather because we put more effort into ensuring that licence holders really do have our very latest data. We carry out daily updates.
If someone buys a paper chart from us on day X, they will have the most up-to-date version available. It is exactly the same with electronic nautical chart data for licence holders. This is different from the WMS service. Although the data often looks similar, the quality is not comparable.
Would you use FreeNauticalChart to navigate yourself?
I would like FreeNauticalChart to enter into a licence agreement with us and then make our quality-assured data available. Of course, a business model would have to be developed for this, and it could no longer be made entirely freely available. But the more users there are, the more it would be an interesting model for fostering greater competition in the market. I could certainly imagine that this could develop into a sound business model.
Have you got in touch with Adam Lucke?
Not yet. But I’d be happy to have a chat with him. He’s also welcome to get in touch with our Customer Service team, who regularly deal with queries like this. I’m very open to having a conversation with him.
To summarise: Certain data must remain in the public domain, but specific quality-assured data is still being sold on. Would it still be possible to navigate relatively safely using FreeNauticalChart?
The data is not suitable for navigation and must not be used for that purpose. Depending on how one handles geodata that is freely available and where there is no guarantee – through encryption or other means – that it will reach the end user on board unchanged, there is always a risk that it will not work. I would definitely recommend using the high-quality nautical chart data from the BSH, which we provide through our licences.
You once said that Mars is better mapped than the oceans. Is FreeNauticalChart a step in the right direction, or is it part of the problem?
The aim is to provide or generate seabed data. For German waters, we are currently working to keep the data up to date and to survey it at high resolution. However, the Baltic Sea, for example, is poorly surveyed in its deeper waters. This is a major issue for people who want to use our freely available data to carry out modelling or improve information on ocean currents. Our hydrographic data is therefore not just for navigation itself.
There is still a lot to be done. But a great deal has changed since I made that statement a few years ago. Globally, the proportion of the seabed that has been adequately surveyed has now risen from six per cent to 27 per cent.
The interview was conducted by Timm Kruse.
Antonia von Lamezan
Volontärin