Development of autonomous vessels is expected to create a paradigm shift in how warfare is conducted. Therefore, there is need to explore the possibilities and limitations in developing integrated systems for defence at sea to support innovation. Fleet modelling can analyse functions and other design options such as autonomous platform’s and evaluate their added effect in naval operations. However, due to the complexity of naval operations, it is not feasible to create a tool that covers all aspects needed to mimic reality. This study, from the perspective of naval tactics, investigate the value of a tool that analyses potential fleet architectures including autonomous platforms. The study identifies that the tool creates relevant mental models for future naval fleets by identifying feasible fleet compositions. However, the proposed fleet combinations are only tested against a limited set of tactical needs and can only be seen as a starting point for development.