Towards the development of a system-theoretic model for safety assessment of autonomous merchant vessels

•System-theoretic model of an autonomous merchant vessel's safety is presented and analyzed.•Method of uncertainty assessment in safety-driven design is introduced.•Recommendations for safety-driven design of autonomous vessel's system are given. As the initiatives to develop and implement autonomous merchant vessels into the global shipping industry are gaining momentum, their safety remains in the spotlight. It is argued that every effort shall be taken to ensure that the safety of maritime transportation is not reduced in the process, but the question of how to achieve it remains open. Meanwhile, the systemic approach is more widely being used to analyse innovative systems’ safety. We therefore apply a System-Theoretic Process Analysis to develop a model suitable for safety analysis and design recommendations’ elaboration for future autonomous vessels. Furthermore, we introduce a method of evaluating and communicating uncertainties pertaining to the method. The results indicate that the system-theoretic safety analysis’ outcome can be affected by manageable uncertainties despite the fact that the system in question is yet to be implemented.