On computational algorithms implemented in marine navigational software used in marine navigation electronic devices and systems

In the paper the authors attempt to present the computational problem related to the navigational algorithm (meridian arc formula) implemented in the software applied in marine navigation electronic devices and systems, such as GNSS (GPS, GLONASS, Galileo), AIS, ECDIS/ECS, and other marine GIS. From the early days of the development of the basic navigational software built into satellite navigational receivers, it has been noted that for the sake of simplicity and a number of other reasons, this navigational software is often based on the simple methods of limited accuracy. It is surprising that even nowadays the use of navigational software is still used in a loose manner, sometimes ignoring basic computational principles and adopting oversimplified assumptions and errors such as the wrong combination of spherical and ellipsoidal calculations in different steps of the solution of a particular sailing problem. The lack of official standardization on both the ‘accuracy required’ and the equivalent ‘methods employed’, in conjunction to the ‘black box solutions’ provided by GNSS navigational receivers and navigational systems (ECDIS and ECS) suggest the necessity of a thorough examination of the issue of sailing calculations for navigational systems and GNSS receivers.