Dear readers,

"Everything is actually fine on board, only the plotter sometimes goes crazy!" A sentence uttered in Rees after returning home from the jetty. "There's probably nothing wrong with your plotter," I reply. And ask whether the issue of GPS malfunctions on the Baltic Sea is well known. Of course it is. But here with us? Yes, unfortunately. Even here, or rather where we are sailing now, during the holiday season.

The conversation reminds me of the disbelief that creeps over some people when they find out that they have a rare disease. Sure, everyone has heard that it exists. But affected yourself?

My counterpart takes it in his stride. "Then I can save myself the trouble of hiring a yacht electronics engineer," he says and adds, almost romantically, "I still know how to sail without GPS!"

Now there is plenty to talk about for the whole evening. What follows are anecdotes from a time when even electricity on board some yachts was still frowned upon as "new-fangled stuff" - albeit mostly due to the conditions in the years when sailing was permitted again after the war and equipment was in short supply.

There are lovely old stories of railing logs and meridian tethering, of foggy approaches with the hand plumb bob as the only aid, of hours of plotting on the unlit steering compass and of counting the identifications of beacons at night, which were necessary in order to obtain at least some certainty from a cross bearing as to whether the coupling point was approximately correct or whether more or less current or drift had to be taken into account.

I attribute the stories of the bakery navigation (getting bread rolls after arriving to read where you are on the bag) to the late evening, but still express amused astonishment, because I am a polite person.

I walk to the bunk somewhat thoughtfully. Because I am actually confronted with a new reality, which I had read about so farbut which I have suppressed like the aforementioned patient his diagnosis. I now realise that prudent navigation in my area this summer really does involve not relying on the GPS location.

In my mind, I'm travelling with my boat without a plotter or chart app. Am I even ready for that? There are no plans for a big trip across the sea this summer. But what if fog does roll in or the weather conditions force me to sail out of sight of land?

I'm confident enough to do this on the paper chart. The log and plumb bob work, the course ruler is always to hand, a decent bearing compass sits in its holder on the chart table, and handling all this was part of everyday life on board in my early years under sail.

However, an easy-to-read steering compass is also and above all indispensable for classic navigation, and you should be reasonably familiar with its deflection. I remember talking to a sailor who thought that the compass in the cockpit was unnecessary due to modern navigation electronics. He probably wouldn't even be able to steer by it for hours, which is essential for proper dead reckoning.

But if I'm honest, that's where it starts for me too: only last summer, I remember now, I made a firm resolution to improve the compass lighting at night in the Great Belt. And over the past few years, I've installed all sorts of things on board, but never checked the effect on the compass.

More on the topic:

• Swedish Maritime Administration warns of GPS interference
• GPS interference on the Baltic Sea
• Alternative to the GPS system is being trialled
• Additional navigation marks due to GPS interference

I think to myself that I could probably manage and fall asleep, but the next morning I wake up with the intention of taking the topic of navigation a little more seriously again.

Even those who manage without news on board and try to escape everyday life in this way have to admit that GPS interference is part of our sailing reality for the time being. The Swedish Sjöfartsverket officially warns against thisin the southern, central and northern Baltic Sea as well as in the Gulf of Finland and the Åland Sea.

It is assumed that the faults are part of the hybrid warfare and from Russian military bases, or the shadow fleet go out.

In practice, this means that the receiver loses the signal. This can be recognised by displaying the satellites in use. If only a few are being used, this may be due to interference. This usually works in such a way that a stronger interference signal overlaps that of the satellite.

An indication of such a fault may be if the speed displayed by the GPS device fluctuates unusually strongly. Or that the ship's position jumps. If only an incorrect location is displayed, the error may remain undetected - and that is the real danger for us sailors.

Co-locating or, when it comes down to it, determining a location terrestrially should therefore be part of the routine on board again. As part of a - hopefully not permanent - new reality.

Lasse Johannsen

Deputy Editor-in-Chief of YACHT

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