Experience reportBack to map and compass due to GPS malfunctions

YACHT-Redaktion

 · 10.10.2025

Carefree sailing on the Baltic Sea is unfortunately not always a given these days.
Photo: Andreas Auras
Russian military forces are apparently deliberately jamming GPS signals. This also affects sailors in parts of the Baltic Sea. A Berlin skipper reports on a trip that went completely off the rails, at least on his sat nav app.

Text by Andreas Auras

On 1 July this year at 9.42 p.m. it happens: just north of Nidda in Lithuania, we run aground on the beach of the Curonian Spit with our "Boe". I swallow briefly and look at the depth sounder. It shows a water depth of 84 metres. Then I look back at the display of the tablet we are using for navigation, which has just located us on the shore. But although barely two or three seconds have passed, we are already in the Lithuanian hinterland near Šilute.


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And we are fast, 54.6 knots over ground - wow! Wordlessly, I hand the tablet to my co-sailor Felix and start another sat nav app on my mobile phone. It takes a while for it to boot up and determine a position. When it does, it's the same: the Lithuanian mainland. And the ship is still travelling at more than 50 knots. Over land!

But we are not travelling in an amphibious vehicle, nor have we sailed more than 100 nautical miles. There's open water all around us. Felix looks up at me from his tablet and then says: "We're prepared for this." I nod. Aren't we?

Risk assessment before starting the cruise

Looking back. A week earlier in Stralsund. "Where are you going?" - "To Lithuania." - "You're crazy!" I just shrug my shoulders. But the man at the next table, also a sailor, adds: "That's dangerous! I wouldn't do that." I'm tired of explaining myself and our plans. Over the last few days, I've heard these warnings again and again. First in Kiel, where I said goodbye to my partner on the ferry to Klaipeda - she couldn't make the journey by sailing boat for health reasons. Then in Rostock, the home harbour of our "Boe". The day before yesterday in Greifswald and now here in Stralsund again.

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Of course I had weighed up the risks, again and again. But part of my family lives in Lithuania. I haven't seen them for a long time. And the sea area off Kaliningrad, the Russian exclave between Poland and Lithuania's Baltic coast, could be sailed around. This Russian Exclusive Economic Zone (EEZ) stretches roughly from the centre of the Vistula to the centre of the Curonian Lagoon and extends 70 nautical miles out into the Baltic Sea. Even though the economic zone is not a national border, foreign sailors should keep clear of it. The Russians can't take a joke if you get too close to their territory.

Nevertheless, Arved Fuchs had only arrived in Klaipeda with the "Dagmar Aaen" a few days earlier. He had set off with his shark cutter from Swinemünde and sailed around the Russian EEZ. We, on the other hand, had wanted to make the long journey eastwards from further north, from Utklippan. This way, according to the plan, we would stay north of the EEZ from the outset.

The crews of the guard ships do their job

However, patience is required until the journey begins. Two days later, "Boe" is still in Stralsund. The anemometer shows a strong 22 to 25 knots, in gusts over 30 knots. I tie the second reef into the main. Felix arrives in just over an hour. The two of us want to set off.

It's supposed to calm down in the afternoon, but it's 7.15 pm before we cast off. Only then does the wind slowly die down. Felix is clearly enjoying himself at the helm. Despite the reefed sails, "Boe" is travelling at seven and a half knots northwards from Stralsund and into the sheltered Hiddensee fairway. Later, we speed along the north coast of Rügen into the night and finally set course for Bornholm.

The next morning we are standing at the south-east corner of the Baltic Eagle wind farm. Dead calm. As we start the engine, the guard ship "Merkur" politely but firmly asks us to leave the area. We are too close to the first wind turbine. Admittedly, we are no longer the prescribed half nautical mile distance. We quickly turn away.

The radio contact makes us realise that the crews of the guard ships out here are doing their job. Since the attacks on the Nordstream pipeline and on power and data cables running along the bottom of the Baltic Sea, they are certainly taking their job more seriously than perhaps they did before the war in Ukraine.

We motor northwards between the "Baltic Eagle" and the "Viking" and soon find the wind again. It takes us all the way to Bornholm. Almost exactly 24 hours after leaving Stralsund, we arrive in Allinge in the north of the island. Stage one is complete.

Good old map work in case of GPS malfunctions

Four days later. Bornholm lies astern. However, we only set off from there yesterday lunchtime. The wind didn't want to co-operate, so the planned beat northwards to Utklippan didn't work out. So we set a direct course east-north-east towards Klaipeda. Initially we made good progress, but during the night the previously steady breeze died. A lot of sailing work. Butterfly with the genoa unfurled, then break up again and set a clear course because otherwise we'd get too far south. And the whole thing all over again.

Now, as we enter the second night, there is almost no wind again. The wind steering system just about manages to keep us on course at a speed of 1.5 to 1.8 knots. But I don't like that. And then, at 9.42 pm, when I want to check our position on the tablet, I can't believe my eyes. According to the navigation app, we are sailing over land at high speed. The GPS signal is obviously being massively diverted.

"It's been a long time since I had to link the ship's position. That was before GPS was available. Now I'm glad I can still do it."

Our last verified position is 55°51.35' North and 18°24.30' East, 18 nautical miles west of the Russian EEZ. We have been coupling every hour from Allinge. The Danish sailors were much more relaxed about our destination, but warned us that the GPS interference would sometimes reach as far as Bornholm. So the good old map work seemed to us not only to be great training, but to make sense right from the start. So now the time has come.

GPS fails - has everything been thought of?

The sun will set in half an hour. Shortly before the end of my watch, I check the latest weather forecast and decide: "There's not much wind in the forecast. But it's only supposed to pick up again in the morning. Let's start the engine. I want a clear, controllable speed for coupling along. After all, we have to get close to the EEZ and then upwind. I don't want to bob around uncontrollably."

Felix nods, is already at the engine panel, glows up, starts the diesel, checks the coolant and stands behind the wheel. I furl the genoa, close up the main, which we leave as a support sail, then go below deck and switch on the position lights and the steamer light. Only now do I feel my tension.

How long has it been since I had to rely solely on the most precise coupling possible? Bloody long! When there was no GPS. I do remember that the GPS also failed later on. But back then we were close to land, could take cross bearings and find our destination that way. I look at the position marked on the nautical chart. Just a cross. No circle. I did a bit of maths. Three quarters of an hour at 1.7 knots plus 15 minutes at 5.5 knots. We went to 50 degrees to keep a little more clear of the northern tip of the Russian EEZ than originally planned. On this course, chart deviation and compass deviation cancel each other out, which is very practical. I make a brief note: "Caution when changing course!"

Power and wind offset are negligible. While I'm still thinking about whether I've thought of everything, my gaze falls on the display of our radio. We have one with integrated GPS. The position displayed matches the one I've just entered on the chart almost to the second. Is the spook over yet? But in the app on the tablet, we are still cruising through the Lithuanian interior, as well as in the other app on the smartphone.

Extent of interference: unclear

I look at the radio again. It shows my calculated position, the decimal places change slightly. But I don't dare draw a circle through the coupled position. I write another note in the position list: "VHF may be displaying correctly - observe!"

I hardly get any sleep that night. "What are you doing here already?" Felix asks me as I emerge from the aft cabin shortly after midnight. "Sleeping in," I reply. He sits at the chart table and continues drawing. He has disengaged the engine and we are drifting. It's time for me to finally install the electric autopilot. It's been lying unused in a cupboard for four years. We've never missed it since the wind vane adorned the stern.

But it would be helpful tonight. My head is already starting to do the maths: ten minutes of drifting plus 50 minutes of engine power, when Felix interrupts my thoughts. He says: "The radio seems to be showing the right positions all the time. The apps have also shown credible positions and courses from time to time. But now we're supposedly sailing around Kaliningrad."

"Hmm," I murmur. Felix adds: "Oh, and the Polish warship is still reporting in every half hour." For several hours now, the Polish cruiser's radio officer has been asking all maritime radio stations to report any "suspicious observations" to her on channel 73. They were fighting for "Freedom of Navigation". Felix asks: "Aren't you going to report to them after all?"

"A Polish warship calls for suspicious observations to be reported. They would fight for freedom of navigation."

I just shake my head, can't see any sense in our report. Except excitement. "And you, are you tired?" I ask him. "Yes, I am," he replies. "Then let's move the watch schedule to local time. That's just fine. I'm fit now. Then you can hit the hay earlier." Felix reluctantly accepts, but is happy. I put on a jacket and take a seat in the cockpit. Before I engage the engine again, I call down: "Maybe we'll be sailing again on your watch!"

Maybe that's what it's all about: annoying and unsettling

And indeed, it's a quarter to two in the morning, we've rounded the Russian EEZ and are just entering the Lithuanian one when the wind picks up. What a welcome! I disengage the clutch, unroll the genoa, then stop the engine. After the roar of the engine has stopped, that inimitable atmosphere that only exists when sailing spreads out: the sound of the sea and the lapping of the waves against the hull, the quiet groaning of some sheet on a deflection block, the whisper of the breeze in the rigging and the gentle gurgling of our stern water. Nothing else. Ten to twelve knots from the south-south-west, us at 100 degrees - a wonderful half-wind course. I'm going to upwind a bit more and let "Boe" run.

Then I activate the windvane control and set the guest flag, yellow over green over red. The lights of an unknown ship within the Russian EEZ can be seen to starboard. I pick up the binoculars. Now white over green and the white light clear astern. Just like the tip of the EEZ, we have also avoided this mysterious ship. It is not visible on the AIS. Probably a Russian guard boat.

Finally, I go below deck to make tea. While I wait for the hot water, it's time for our hourly position. The integrated GPS in the radio has not been fazed the whole time and has provided plausible information. The manufacturer, Navico, is later unable to explain why. The apps also worked properly from time to time until we were supposedly sailing towards the coast again. Right now we are supposedly sailing through Kaunas.

I wonder what this rubbish is all about. The supposed positions and associated speeds are so nonsensical that nobody can assume they are there. Minor deviations from the actual position would be much more dangerous. So it's all just annoying. But perhaps that's exactly the point: to annoy and unsettle.

Arrival in Lithuania

Shortly after five in the afternoon, we are standing in front of the harbour entrance to Klaipeda. "Port control, port control. Here is sailing vessel Boe, sailing vessel Boe, Delta Hotel two nine three zero. Do you read me?" Hours earlier, the wind had deserted us again. When we became so slow that we were in danger of only entering the foreign harbour at night, we started the engine again. Now we disengaged the clutch so that we could radio in peace. The engine is pretty loud below deck. And so we drift south of the approach fairway with the rest of the journey left.

"Sailing vessel Boe, here Port Control. What are you doing here?" comes an energetic female voice on the radio. "Lãbas vãkaras. We are requesting entry to the harbour," I reply, hoping that my little bit of Lithuanian comes across well. "Sailing vessel Boe. Spell the name of the boat and give the call sign and MMSI!" I comply with the request. It takes a while before the woman answers again: "A good entry. Report to the coastguard on channel 77! Lãbas vãkaras." So then the coastguard too. The whole thing is repeated. I have to spell everything twice. Because of possible contradictions? I'm nervous. Then: "How many people are on board, what are the tasks on board, what nationality are they? And what are your intentions here?"

When I mention that Felix is a Swiss citizen, I'm afraid things might get complicated. So I quickly add: "And we're here to visit my grandparents-in-law. They live in Melnrage and there's a barbecue tomorrow evening." That obviously helps. "Well, have a good time and welcome to Lithuania. Let me know when you leave again!"

As we moor alongside at the harbour quay, my partner and a good friend and her son are already waiting for us to give us an exuberant welcome. And tomorrow we're having a family barbecue!

Tension in the eastern Baltic Sea is palpable

Epilogue. We had a carefree time in Lithuania. On the way back, we are still tying up the last mooring lines in Karlskrona when the Swedish coastguard approaches at a brisk pace, four of them, armed. Here, too, we are questioned about our nationality, where we are from, what we have been doing there and how long we are staying. Only when we are asked about pets on board does the situation relax. A stuffed rabbit is sitting on deck with us; we fished it out of the harbour basin in Klaipeda. "Just this one," I reply and point to the rabbit. The coastguard finally grins and says goodbye.

Felix and I look after them, probably both thinking the same thing. The tension in the eastern Baltic Sea is palpable, the threat to the people here is very real. As sailors, we can't escape it. But it shouldn't stop us from sailing.

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