Ship engine room fire is one of the major dangers that threaten the safety of the ships. An effective firefighting in the engine room is critical to prevent possible destructive consequences on-board ship. Fire detection and firefighting systems, which are designed for an effective fire prevention on-board ship, need to work flawlessly. In order to achieve this, the deficiencies of the designed systems must be determined and necessary control actions must be taken. In this study, failure probabilities of fire detection and firefighting systems on-board ship is calculated by event tree analysis and fuzzy logic environment. The possible consequences that may be encountered in case the systems fail under various scenarios are determined. Solutions have been proposed in order to minimize the risk that may arise by reducing the failure probability of each system. The outcome of this paper will be utilised by safety engineers, shipping companies and safety inspectors to prevent potential engine room fires.