50BC has the disadvantage in terms of operating cost, port cost, fuel cost and icebreaker fee. However, the capital cost is considerably less than that of 40BC, which resulted in lower total cost. A number of voyages through the NSR ranges from 6.1 to 7.4 and the difference between 40BC and 50BC is small. 50BC has more speed in open water, which reduces voyage-days in the SUEZ route' As a result, 50BC can make more voyages and transport more cargo. This condition is favorable to reduce the freight cost of 50BC. Table 4.2.4 shows the total of annual costs, annual amount of transit cargo, and annual freight costs of 40BC and 50BC calculated in 1960, 1970, and 1980.
The freight cost of 50BC is superior in both the NSR and SUEZ route. The following factors can be pointed out ;
1) The low capital cost of 50BC reduces the total cost.
2) 50BC has lager amount of transit cargo than that of 40BC with the approximately same voyage-days.
3) 50BC is capable to transfer more cargoes than 40BC in the SUEZ route since 50BC is faster in open water than 40BC.
4) Icebreaker tariff being the most part of icebreaker fee adopted as a flat rate, the difference of escorted days does not significantly influence the total costs.
Therefore, in the next chapter, 50BC was selected as a representative ship type for the routing selection simulation in which the NSR and SUEZ route are switched successively judging the ice condition (integrating ice index) of each year.
