The wind farm technology block in Fig. 1 provides project information, such as turbine number, monthly capacity factors and components. Failure rates, repair times and costs are inputs for each component. Strategy and resources provides details of technicians and vessels available to conduct maintenance. The site meteorological condition data is provided as a time series of wind speed and wave height data which is used to determine length of access windows for maintenance operations for a given site. Within the meteorological simulation the time series data is randomised. A probabilistic failure event model is used to simulate failure occurrences using an inverse transformation sampling algorithm. It formulates dates according to distributions based on the lifecycle of the component related to the bathtub curve [20], as shown in Fig. 2[21]. The model is capable of simulating corrective and time-based, but not condition-based, maintenance. After a corrective maintenance action occurs, the component is returned to an “as bad as old” state, a conservative assumption. Other information sources used in the model are deterministic costs and strategy chosen by the user. The mean cost and exceedance probabilities are calculated using Monte Carlo simulation [20]. The results from the tool are used to assess the estimated cost of a particular strategy based on best available data and compared with other possible maintenance strategy solutions.