3.2 Monthly voyage simulation (MVS)
The monthly calculation over for forty years is possible at one run. It makes possible to study the trend of the operation feature by month and/or year.
Figure 3.2.1 shows the main flow of the simulation. The whole simulation consists of four prime modules： DATA READ module, VOYAGE SIMUIATION module, COST CALCULATION module, and RESULTS OUTPUT module. DATA READ module is common to the annual serial voyage simulation (ASVS).
Data input and reading
Figure 3.2.2 shows the flow of DATA READ module. The all data needed in the NSR simulation is read or input from the data file.
Control data and condition data
Control data and condition data for the simulation are read from data files. The control data specify a simulation mode, output formats, conditions for judging escort, conditions of probability calculation etc. As the condition data, a type of cargo ship, a route, a departure port, an arrival port, the month and year of the operation are selected. Also cost parameters such as icebreaker tariffs and crewing costs are input from this file. Relationships between ice index and ship speed, and port data, are also input.
From the data files for voyage routes supplied by WP1, Route data selected by the above condition data are loaded. Referred data are route point No., latitude and longitude of the way points, and distances of segments between adjacent points.
Among the environmental data file supplied by WP2, data sets related to referred route, year, and month selected by the above condition data are loaded. The sorts of reference data are stated in chapter 2.2.
A ship data file contain data specifying ship performance. The ship data selected in the condition data is loaded from this file.
Figure 3.2.3 illustrates the flow of one voyage simulation. The ship speed and the voyage time at each segment is estimated in order along a route. As for MVS, the simulation starts on the first day of that month. However, it is not the day when the ship departures the port but is defined as the day when cargo-loading begins at a selected port. For instance, if it takes three days to prepare a departure, the departure of the ship would be the fourth day of that month.
Thus, there is no difference in the both results of westward and eastward. Here, the direction of voyage is determined from Far East to Europe in all cases.
Cost for one-voyage
Figure 3.2.4 shows the flow of the cost calculation in MVS mode in COST CALCULATION module. The items of one-voyage cost and their calculation methods had been explained in the chapter 3.1.