Satellite navigation is now widely used in a land, sea, and air transport. It is easy to forecast the negative effects related to the lack of a signal of the Global Navigation Satellite System (GNSS), especially in the aviation and maritime traffic. In 20th century they were allayed the terrestrial navigation systems, e.g. Decca, Omega, Loran-C. Recently, only eLoran is used, as a backup system for GNSS. The Polish Defense Ministry plans to develop a new navigation system that should provide positioning data for the Polish Navy ships that will carry out combat missions in coastal areas, regardless of GNSS. This paper presents the concept of a reserve navigation system (RNS) that is based on the signal Doppler frequency (SDF) location method. Effectiveness of RNS is shown on the basis of simulation studies. Obtained results indicate the possibility of the vessel positioning on the basis of signals from one or more radio beacons of the system.