Abstract
Performing maintenance operations at offshore wind farms involves one major challenge compared with the onshore counterpart: All maintenance personnel and spare parts need to be transported from an onshore port or offshore station to the individual wind turbines by vessels or helicopters. The vessels and helicopters required for these tasks will constitute a major part of the maintenance costs for the offshore wind farms, and to reduce the cost of energy it is essential to keep an optimal or near-optimal vessel fleet for this purpose. We study the vessel fleet optimization problem that arises for offshore wind farms and propose an appropriate optimization model. Computational experiments show that our model can be solved to provide decision makers with an optimal vessel fleet within acceptable time limits.