The maritime radiobeacon differential GNSS service in Europe has recently been reorganised with the aim of having at least two of the 162 stations serve each critical coastal location. Maritime administrations have now set specifications for the availability and continuity of the service. The paper analyses these requirements, noting incompatibilities between them. It proposes a method of predicting the performance of beacons, employing IALA standards. This takes into account each beacon's own availability, and propagation factors that include groundwave signal attenuation, interference, and skywave fading at night. Availability, continuity and coverage maps produced by the new programs are presented in the paper.