In this thesis the current anchoring situation, especially in terms of occupancy and space use within anchorages, in the anchorages in the offshore approach of the port of Rotterdam in assessed by means of data analysis of historical data. Using this data analysis as input a stochastic simulation model is constructed in MATLAB to assess occupancy and evaluate capacity in these anchorages. With the contructed simulation model the current anchoring situation in the anchorages in the offshore approach of the port of Rotterdam is modelled correctly and accurately, and furthermore the model is generic and hence can be used by many other ports as well.