Record number of GPS disturbances near Bornholm: Jens sailed for 24 hours without a signal

A GPS that stops working or completely misidentifies where the ship is. That is what Jens Nielsen experiences more and more often, since the war in Ukraine started back in February 2022.

He owns the cargo ship Saturn, where he is also the captain on board. The ship has a total of four crew members and often carries cargo around the Baltic Sea. Normally, there are only problems with the GPS for 15-20 minutes at a time, but recently it has been worse than ever.

"On July 29, we lost the connection for about 24 hours between Gdansk and southern Gotland. On our most recent trip from Gdansk and back to Hundested, we had no signal all the way until Bornholm. That was around twelve hours," says the captain.

Captain Jens Nielsen often experiences GPS jamming and GPS spoofing on his ship. "Here is an example from July 29, where the ship Saturn was located about 20 nautical miles north of Gdansk in Poland, but the GPS showed that the ship was in the middle of land at Kaliningrad." (Photo: © Jens Nielsen, DR)

Jens Nielsen experiences that the problems occur in the southeastern Baltic Sea, and when it happens, you have to resort to old-fashioned methods.

"Then it's just a matter of steering by the helm and finding the magnetic compass, because the autopilot stops working. It works, but it is annoying, and it requires a person to stand and steer manually. It creates more work."

Last, but not least, there is also the problem of accuracy. Jens Nielsen says that the old-fashioned method is less accurate. "Then you cannot know within a few meters where you are. The problem is also that several shipping routes are only marked electronically."

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Probably not a deliberate attack

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On Bornholm, it is a measuring station at Tejn that registers the GPS disturbances. This year, it has measured around 30 cases of GPS jamming and spoofing, while the total number for last year was 16.

The measurements cannot, however, reveal where the disturbances come from, but that does not mean you cannot make qualified guesses. So says Søren Reime Larsen, who is a researcher at DTU Space and specializes in GPS jamming and spoofing.

"Since the war in Ukraine, we have seen a significant increase in the number. That is because GPS is used extensively in military technology such as drones and missiles. Therefore, it is quite obvious that in an attempt to defend yourself, you go in and disrupt these signals," he says.

Søren Reime Larsen is not aware of cases near the Sunshine Island where GPS jamming and spoofing have had serious consequences. However, it can affect shipping traffic in the Baltic Sea.

"When we get these measurements from Bornholm, I actually do not think it is a deliberate attack on Bornholm's infrastructure. It is more of a side effect," he says.

The authorities in a long list of European countries – including Denmark – accuse Russia of being behind the disturbances of the navigation systems in the Baltic Sea. They made this known, among other things, in an open letter ( https://kliimaministeerium.ee/sites/default/files/documents/2026-01/Open%20Letter%20by%20the%20Coastal%20States%20of%20the%20Baltic%20Sea%20and%20the%20North%20Sea%20with%20Iceland%20on%20the%20Growing%20Risks%20to%20Maritime%20Safety%20%20to%20the%20International%20_.pdf ) from January, where they also write that the disturbances pose a danger to ship safety.

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What is GPS jamming and GPS spoofing?

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*GPS jamming* is a powerful radio signal that is deliberately emitted to drown out the satellite signals that electronic devices use to navigate and determine their position. It can be compared to trying to hold a conversation during a concert with very loud music.

*GPS spoofing* is falsifying a GPS signal, so the receiving equipment believes it is in a different place than it actually is.

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An expensive upgrade

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The captain on board the Saturn is not exactly optimistic about the prospects of the GPS problems ceasing anytime soon. It might even get worse if the war in Ukraine escalates, he fears. Therefore, he has started looking into what he can do himself, but that turns out to be an expensive affair.

The price is around 100,000 kroner if Jens Nielsen is to have a new type of satellite navigation system installed on the ship, one that is not only dependent on GPS signals but can connect to multiple signals. It would most likely solve his problems for now, but he does not know if it is a long-term solution.

"You never know if those who are jamming will start jamming the other frequencies when they find out that the ships have switched equipment. It may be that we just have to get used to not being able to sail with the same certainty about our position as before. We certainly have to be more aware that there can be errors," says Jens Nielsen.

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