3.4. Ship arrival rates
Table 1 shows how many ships of each type arrive per year. For each product/cargo type, the number of ships carrying it is chosen such that the total amount of cargo transported matches the plant’s capac- ity. For instance, per year, the plant processes 1,070,000 tons of raw material A. Therefore, the total cargo capacity of ships carrying product A into the port needs to be 1,070,000 tons, which can be veri- fied from the table. This implies that among simulation runs, only the mutual order of arriving ships and their interarri- val times are variable. Thus comparisons regarding port efficiency among arrival processes are kept clean (i.e., devoid of other circumstantial factors such as random fluctuations in production). With constant loading and unloading times per ship type, fixing the number of ships implies that the utilization rate of the jetty will be the same for all arrival processes. In our case, the utilization rate is 61%. According to industry norms, this is considered to be busy but not overloaded