Constraint-based local search for container stowage slot planning

Due to the economical importance of stowage planning, there recently has been an increasing interest in developing optimization algorithms for this problem. We have developed 2-phase approach that in most cases can generate near optimal stowage plans within a few hundred seconds for large deep-sea vessels. This paper describes the constrained- based local search algorithm used in the second phase of this approach where individual containers are assigned to slots in each bay section. The algorithm can solve this problem in an average of 0.18 seconds per bay, corresponding to a 20 seconds runtime for the entire vessel. The algorithm has been validated on a benchmark suite of 133 industrial instances for which 86% of the instances were solved to optimality.