Sea transport has become a key-issue for our modern economy. 90% of worldwide traded goods are carried over sea. At any time, 1500 ships navigate the Baltic Sea and connecting the bordering countries to each other and to the rest of the world. Sea traffic has become a fragile backbone for an economy based on “just-in-time” delivery and closely linked manufacturing processes. Due to the steady increase in world trade, an increase in shipping density can be observed. Especially traffic in Particularly Sensitive Sea Areas (PSSA) like the Baltic Sea, requires reliable navigation capabilities. Primary source of maritime navigation are Global Navigation Satellite Systems (GNSS), which are prone to intentional and unintentional disturbances as reported in the eastern Baltic. To increase resilience of maritime transport and reduce the risk of using misleading information, national authorities in the Baltic Sea Region (BSR) and worldwide are seeking for solutions to identify and mitigate GNSS disruptions or deceptions. One solution is the use of alternative systems, not affected by the same error modes, such as the terrestrial R-Mode. The project aims to implement an operational R-Mode system that comprises core functionalities to offer R-Mode positioning in the BSR. Further, additional on-board sensors will identify times when GNSS performance is reduced. The information will be fed into a GNSS degradation monitoring system to inform the mariners of threats for safe shipping.