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 through 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 included in this. We provide this information to licence holders via our distribution channels.
Why aren’t they included? Shouldn’t all data be made public?
No, on the contrary – there are some we are not even allowed to make freely available. Under the Federal Budgetary Regulations, we are obliged to act in an economically sound manner. This means that our products – and these are actual products, not just data – must be sold securely and at a market 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 data, into which we invest even more effort – we are, after all, 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 occur?
I can’t say exactly how that happened. But if you make data available that was actually only intended for licence holders, and there’s a link that allows you to access it – it wasn’t freely and publicly displayed, but it was findable. When we noticed this, we rectified it. 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 great A product that allows you to display tide tables or other information in a visually appealing way. Of course, he didn’t do anything wrong. It wasn’t his fault that there was a gap. That was down to us. That’s why we had to sort it out as soon as we realised.
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, I can’t just 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 doesn’t 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. That is why we make this information available as widely as possible – with the sole restriction that the nautical charts or 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 do with the data. 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 boating market. We used to produce recreational boating charts 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 become public knowledge, we asked: How did this happen? And then we fixed it. Of course, we also think of our licence holders in the second instance, because I would 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 standard international wording. The international standard is "not to be used for navigation". This is also the case in aviation, for example, with aeronautical charts. When translated, this is a more stringent formulation than "not suitable". We must point out that the information provided via the WMS services is not verified navigation 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 disclaims all liability. Why should we 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 they do and how reliable their equipment is. I fully understand that electronic chart data makes navigation much easier than using paper charts.
However, it’s important to realise that the data can never be 100% accurate. We carry out wreck surveys; we search very thoroughly for objects – but there’s always the possibility that there’s a rock we haven’t spotted. You have to demonstrate good seamanship. But there is a difference between a buoy not being marked exactly in the right place and depths not being accurately represented 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 a way that people can rely on. 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 does this monthly on the main shipping routes; we at the BSH cover a wider area. In very shallow, sandy areas, depth changes of several metres are entirely possible within a short period of time.
They update the notices to mariners every week. But that information doesn’t appear on my printed paper chart.
That’s right. But there’s a big difference compared to topographical maps on land. We have to ensure that our official nautical charts are always up to date. If the weekly update cycle, combined 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 finds a new wreck and it is urgent, the information is passed on immediately to the 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 is an accident – I can trace the issue: where did the problem lie? Was the chart data incorrect or out of date? Thanks to our quality management system, we can trace this right back to the individual survey vessel deployment.
If I do this via a WMS service, where anyone can download data 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 regulations 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 and 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 our licence holders really do have our very latest version. 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 to see FreeNauticalChart enter into a licensing agreement with us and then make our quality-assured data available. Of course, this would need to be turned into a business model and 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 been 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; they deal with these sorts of queries on a regular basis. I’m very open to having a conversation.
In summary: Certain data must remain publicly available, but specific quality-assured data is still being sold. Would it still be possible to navigate relatively safely using FreeNauticalChart?
The data is not suitable for navigation and should not be used for that purpose. Depending on how you handle 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. But 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 current information. Our hydrographic data is therefore not just for navigation itself.
There is still a lot of work to be done. But a lot 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.
Antonia von Lamezan
Volontärin
