Autonomous navigation will play an important role in the future of the shipping industry. Hence, this study illustrates several concepts that should support the navigation side in relation to the collision avoidance of autonomous ships. The concept of system intelligence, i.e., cloned by human navigators, as the digital helmsman to navigate future vessels is discussed in the first part of this study. That can provide an adequate solution to the ship controllability problem. A collision avoidance framework. i.e., based on fuzzy logic, developed to support the digital helmsman is discussed in the second part of this study. The same collision avoidance framework complements the digital helmsman. Future vessels will navigate in a mixed environment, where manned, remote controlled and autonomous vessels are interacting. Hence, the proposed collision avoidance framework, as a decision support feature based on the respective navigational rules and regulations, should support both humans as well as systems to make appropriate actions in such a navigation environment. It is expected to have an adequate consistency between human and system collision avoidance actions to preserve the integrity of system level intelligence. In the third part of this study, the consistence between human and system decisions/actions in critical collision avoidance situations with the main intention of identifying possible regulatory failure situations in a simulated environment are investigated by using the same collision avoidance framework.