Satellite Navigation Systems (SNSs), the GPS system in particular, were available to civilian users from the beginning. The first community interested was the maritime one, for both professional and recreational purposes. Marine navigation distinguishes between five major phases, among those the port approach and operation in restricted waters and the marine navigation in the port. SNSs, today the GPS system and its differential mode DGPS, and Satellite Based Augmentation Systems (SBAS) as EGNOS and WAAS, provide a wide range of applications in both these phases, e.g. coupling SNS receivers with dedicated sensors installed on the ship’s bridge, e.g. AIS, aid in the berthing and docking of large vessels, by means of the position and the heading reference systems. In maritime restricted area, the SNS position accuracy can be decreased when the masking elevation angle causing by the obstacles is for the user on the ship greater than masking angle of observer’s receiver. This diminution depends on among other things the ship course, observer’s latitude, the height of the obstacle, the distance between the observer and the obstacle, here coast side. Additionally, the problem of availability of the integrity information to users and performances, and future use of the GLONASS system after modernization, Galileo and Compass systems actually under construction, new SBASs, the next DGPS and DGLONASS reference stations, and Eurofix with differential corrections to GPS including integrity messages in coastal navigation are described in the paper

The article presents a method of stochastic modeling of a GNSS position error. Pre-liminary results of DGPS error simulation are presented, a simulation algorithm is de-scribed as well as its application in sea traffic engineering research.

The paper presents an accuracy evaluation analysis of the ship;s heading measured between two GPS antennas of automatic GPS and code DGPS type. The usefulness of the above mentioned GPS techniques for the vessel's navigation and piloting systems in confined waters has also been evaluated.

The paper presents a method of evaluating navigation safety criteria for the specified waterway by means of two DGPS receivers recording synchronised data. The research experiment was performed in Świnoujście harbour (Poland). Availability of satellites during several 24h periods (cycle of a constellation change) was analysed and its impact on position accuracy and integrity in the critical harbour 's areas was evaluated. Finally a method of ship's swept path at specified confidence level, based on the on-board recorded positions' data, was proposed for verification of the safe manoeuvring area.