Containership port time: The bay time factor

摘要

Containership size has been increasing in length, width (beam), and height. The introduction of Ultra Large Containerships results in a much larger number of containers stowed in a cargo bay. The objective of this paper is to determine the impact of the increasing containership bay size on the economies of scale at berth. We develop the concept of bay time, the amount of time it takes to load and discharge the largest cargo bay of a containership based on bay size, in order to determine the minimum amount of time it takes to discharge and load a containership. The analysis establishes that bay time is the foundation and critical path of the minimum amount of time a containership must stay at berth and in port. The study notes that, inherently, an increase in containership bay size involves diseconomies of scale in cargo handling operations, at a given level of gantry crane productivity. We find that there are increasing diseconomies of scale for large containerships at berth. The study also establishes that: as beam/bay size increases, the average cargo handling time of two bays increases by an average of 4.5?h at any productivity level. Bay time declines as crane productivity increases up to the crane’s technological constraint. Furthermore, the larger the beam/bay, the larger the marginal benefits when productivity increases. The diseconomies of scale are stable and predictable at every gantry crane productivity level. The study recommends using bay time as the fundamental measure for containership performance at berth and in port, as well as for voyage planning.