CP and MIP Methods for Ship Scheduling with Time-Varying Draft


  • Elena Kelareva Australian National University and NICTA
  • Sebastian Brand University of Melbourne and NICTA
  • Philip Kilby Australian National University and NICTA
  • Sylvie Thiebaux Australian National University and NICTA
  • Mark Wallace Monash University and NICTA




scheduling, applications, constraint programming, mixed integer programming, operations research, logistics


Existing ship scheduling approaches either ignore constraints on ship draft (distance between the waterline and the keel), or model these in very simple ways, such as a constant draft limit that does not change with time. However, in most ports the draft restriction changes over time due to variation in environmental conditions. More accurate consideration of draft constraints would allow more cargo to be scheduled for transport on the same set of ships. We present constraint programming (CP) and mixed integer programming (MIP) models for the problem of scheduling ships at a port with time-varying draft constraints so as to optimise cargo throughput at the port. We also investigate the effect of several variations to the CP model, including a model containing sequence variables, and a model with ordered inputs. Our model allows us to solve realistic instances of the problem to optimality in a very short time, and produces better schedules than both scheduling with constant draft, and manual scheduling approaches used in practice at ports.




How to Cite

Kelareva, E., Brand, S., Kilby, P., Thiebaux, S., & Wallace, M. (2012). CP and MIP Methods for Ship Scheduling with Time-Varying Draft. Proceedings of the International Conference on Automated Planning and Scheduling, 22(1), 110-118. https://doi.org/10.1609/icaps.v22i1.13494