System dynamics simulation modelling of marinas in relation to investments in sports objects will enable rise of the quality of the total offer and competitive forces of the observed system, and at the end growing satisfaction of tourists. The system of marinas (LNT) has all the characteristics of a complex organisation and business system, for which dynamic modelling efficient methods of simulation techniques have to be used. One of the relatively recent, and particularly exposed and practically proved scientific methods is system dynamics simulation modelling which was developed by the Professor Forrester in the famous world scientific centre of the development of management science - The Sloan School of Management (MIT). This model is developed for the practical training of marine management students. In this paper, the business system of marinas (LNT) will be determined through a global model of integral nautical and tourist service(from berthing service as a basic service to all other additional services). The subsystem of investments in new capacities, like sports and additional capacities will be determined by exogenous variable VINK value of investments in new capacities.