A Nonlinear Programming Model for Optimizing Size and Speed of Containerships

One of the most important decisions for shipowners is to determine how big of a containership to order. The optimal containership problem represents a trade-off between the cost and revenue resulting from size and speed. In reality, there is a tendency toward increasing containership size and speed, which results from some factors related to profit. However, most of the past studies devoted attention to the problem only from the cost perspective. These models neglected the effect of ship speed on profit, and might result in inadequate solutions to the problem. Based on the cost-volume-profit (CVP) analysis, a nonlinear programming model is formulated to approach the problem. The objective function is a strictly concave function with a globally unique optimal. An example of the Trans-Pacific Route is employed to test the model’s formulation. The results provide shipowners with a beneficial reference for planning the size and the speed of their containerships.