|Position fixing in a redundant manner on board of ships, in conjunction with a usual using of satellite navigation and their shortfalls today, ask for scientific investigations. The dissertation provides some algorithms for improving the satellite navigation by ship borne and inertial sensors. Exceeding the combination of GNSS, ways of prediction and filtering of range measurements will be shown. The dissertation is stated that all conventional possibilities to backup satellite navigation on board of ships were investigated and partly improved. For future works the foundations were laid to develop algorithms combining satellite navigation with motion models of ships and inertial sensor data.