Learning to Swim - How Operational Design Parameters Determine the Grade of Autonomoy of Ships

In recent years, ideas and applications for autonomous shipping have been rapidly increasing. In most of today's ship bridge systems decision support systems with different capabilities are installed and officers of the watch rely on them. First tests with fully and constrained autonomous ships are on the way. One of them is the B0 | BZERO project, with the aim of an autonomous 8-hour watch-free bridge, while the ship is still manned. The system's constraints are captured in the operational design domain (ODD) defining all conditions under which the autonomous system can operate safely. We propose the definition of a preliminary ODD considering both regulatory and technical restrictions. Furthermore, we present a new way of defining the level of autonomy of a ship by using the ODD and navigational specifications.