When anchorages are arranged in a harbour, the manoeuvering difficulty of a ship navigating between anchored ships should be considered. However, until now, nobody has researched how to design the arrangement of anchorages from the viewpoint of manoeuvering difficulty. In this paper, the relationship between the arrangement of anchorages and manoeuvering difficulty is systematically analysed by applying the Environmental Stress Model to the problems of a ship navigating between anchored ships. Based on this analysis, a method of designing the arrangement of anchorages is considered that ensures manoeuvering difficulty is at an acceptable level for mariners. The distance needed between the anchored ships has been proposed to accord with the length of the navigating ship and the mean length of anchored ships.