Solving the ship inventory routing and scheduling problem with undedicated compartments

This paper addresses a ship inventory routing and scheduling problem faced by an oil company serving many locations. The problem involves the delivery of multiple products from loading to unloading ports by using heterogeneous types of limited numbers of ships. The nature of the products needs them to be loaded separately into compartments of the ships. However, the compartments are not dedicated to specific products. In this problem, we need to determine the type and the quantity of products to be loaded, the assignment of products to ship compartments, the ship routing and delivery schedules, and the type and the quantity of products to be unloaded at the destinations ports simultaneously. In this paper, we have formulated the problem as a mixed integer linear program for finding a minimum cost solution for ship routing and loading/unloading schedules while satisfying a number of technical and physical constraints within a given planning horizon. We have also developed a one-step greedy heuristic to solve the problem. Numerical examples are provided to demonstrate the applicability and the performance of these methods.