GPS interferences encountered by vessels have increased – boater, remember the traditional navigation methods and the captain’s responsibility

There was a significant increase in the number of GPS interferences in the Gulf of Finland during the spring. Satellite navigation service interferences have especially been observed in the eastern parts of the Gulf of Finland.

Actors within waterborne traffic, that is to say, the Finnish Transport and Communications Agency Traficom, the Finnish Border Guard, the Finnish Transport Infrastructure Agency and Finnpilot wish to remind boaters of the importance of interference notifications. 

In January–May 2025, a total of 84 satellite navigation service interferences were reported, whereas the number for the corresponding period in 2024 was 27. The number of interferences is likely to increase during the summer.

When facing interferences, the ability to read traditional nautical charts is of utmost importance

Electronical navigation aids are popular in boats. However, technical equipment do not replace a boater’s good navigations skills in surprising situations, such as when there are interferences in the satellite navigation. Thus, boaters shall have adequate and up-to-date nautical charts with them for safety reasons. 

‘The number of radio interferences in the Finnish land and sea areas have increased this spring. Therefore, boaters must be particularly careful when navigating using different technical equipment. Mastering navigation based on nautical charts, in addition to observing the surroundings, as well as other traffic, further the anticipation of different situations. This ensures a safe and flowing navigation, when GPS positioning is unavailable’, Maritime Director Sanna Sonninen from the Finnish Transport and Communications Agency Traficom emphasises. 

It is the responsibility of the boat’s captain to actively follow the surroundings and to know the boat’s location. Even in familiar waters, the circumstances may surprise and change, whereby a nautical chart is needed.  This could, for instance, be a situation where an interference disables the positioning of the plotter display. Straying to a heavily trafficked fairway due to erroneous GPS positioning may cause risk situations with commercial vessels. 

‘Having a traditional nautical chart and ability to read it will help, if technical equipment fails. A map and a compass are a reliable combination, when you know how to use them, Head of Maritime Safety Mikko Hirvi emphasises and continues: ‘Maritime search and rescue operates 24/7 – in an emergency, call 0294 1000. Do not hesitate to ask for help. If you can manage on your own by preparing well for your voyage, you save search and rescue resources for the most challenging incidents.’

‘According to the Water Traffic Act, plotter is not the primary navigation tool. The Water Traffic Act requires that there are adequate nautical charts in the boat, where necessary due to circumstances. The increased risk of GPS interferences creates such a circumstance, and thus, nautical charts are required to be found onboard. Furthermore, one shall also know how to read a nautical chart, and the skills must be sufficient for navigation without the plotter in all circumstances. Different parties organise boating training in Finland – thus, it is time to become master in reading a traditional nautical chart’, Traficom’s Leading Expert Kimmo Patrakka reminds. 

Remember to notify Traficom of radio interferences

Actors within waterborne traffic, that is to say, the Finnish Transport and Communications Agency Traficom, the Finnish Border Guard, the Finnish Transport Infrastructure Agency and Finnpilot wish to remind boaters of the importance of interference notifications. Radio interferences that vessels encounter should always be reported to Traficom, who investigates radio interferences and compiles situation picture concerning the interferences in Finland.

The Notification of radio interference form is easy to fill in on your mobile, for instance, directly in the boat or when coming ashore: Notification of radio interference (Traficom.fi)

On the Finnish Transport Infrastructure Agency’s feedback channel for waterborne traffic, you can report defective aids to navigation, defective navigation marks, as well as give other feedback regarding waterways:  Feedback (extranet.vayla.fi)

This text has also been published on the aforementioned authorities’ webpages.