The Royal Netherlands Navy’s (RNLN) fleet is deployed worldwide and its main task is to ensure security at sea and from the sea. In order to conduct its operations, their fleet has to be available and in excellent condition. Despite the efforts of the maintenance department, this goal is not always reached and one of the reasons is obsolescence. Whenever this phenomenon occurs, decisions regarding obsolescence management are made by engineers based on experience and gut feeling. Laurens Hellegers conducted a master thesis project that focused on rationalising obsolescence decisions by developing a decisions support tool.