In the competitiveness determining model, 41 states of the system are observed, out of which 38 relate to nautical tourism ports, and the other three states relate to exit/entrance from/to Italy, Slovenia and Montenegro. Among these states nautical traffic occurs and thus generates a communication network with its principles. Nautical tourism ports act as technologic-economic nodes in the network and form a nautical offer by providing services to nautical tourists. Nautical tourism port competitiveness factors, nautical and charter services interference areas and charter services quality are determined during nautical tourism port competitiveness determining model development. Identified competitiveness factors represent competitiveness determining model input data in the form of criteria and sub-criteria. Nautical vessels transitions among nautical tourism ports represent a unique system whose functioning principles are established by creating a transition matrix and stationary distribution as per Markov chains regulations. The above method gave insights on bottlenecks areas created during the nautical vessels transition among nautical tourism ports. The second part of nautical tourism port competitiveness model provides support to nautical tourists in their port call decision making process which is in accordance with their preferences. The proposed methodology uses two types of input data high-quality filtration. First filtration is based on the transition matrix detecting ports which makes one sub-system of all the identified sub-systems. Furthermore, methodology selects ports with the highest stationary distributions within one sub-systems and finally ranks ports through Promethee methodology. This solved a problem of large number of nautical tourism ports being incomparable. An interdisciplinary approach is used in fundamental scientific hypothesis verification as follows: By science-based knowledge about the nautical tourism port competitiveness factors and by determining the vessels movements probability among nautical ports, it is possible to set up a nautical tourism port competitiveness model, which provides support to nautical tourists in port call decision making process which is in accordance with their preferences. A fundamental scientific hypothesis is confirmed by developing a methodology for nautical tourism port competitiveness determined by integrating Markov chains and Promethee methods.