This paper is dedicated to an overview of components of an onboard control system of an autonomous ship. This system controls and operates the ship. Therefore, this system needs to be able to analyze the ship's state, predict its future development and analyze the consequences of its own decisions. The paper focuses on software aspects of the onboard control system, not the hardware. The paper provides an overview of technologies that can be used to implement the components of such a system responsible for planning new routes, handling the ship during the voyage, ensuring its seaworthiness and safety during the voyage, monitoring an autonomous ship from an onshore control centre, ensuring the robustness of the onboard control system, and collective operations of multiple autonomous ships. The paper describes benefits the maritime industry would gain from deploying some of the technologies developed for autonomous ships on ordinary, human-controlled ships. The paper also describes some challenges, especially in the field of automatic decision and reasoning, arising from the emergence of autonomous and smart ships. The main contribution of the paper is that it summarizes existing research in different areas of autonomous ship technology.

The paper is dedicated to the overview of the autonomous ship onboard control system functionality. The paper is dedicated to autonomous maritime navigation, i.e. to planning a safe and optimal route for an autonomous ship amid the absence of crew on board and to handling an autonomous ship when underway, ensuring seaworthiness and route correctness. Moreover, the paper describes communications of several autonomous ships and autonomous and ordinary ships to infer a collective decision on how to pass safely through a particular area. Since it is expected that autonomous ships are going to be equipped with dozens of sensors and detectors, the paper describes remote monitoring of an autonomous ship when underway. Since an autonomous ship highly depends on its onboard control system, the paper also pays attention to the robustness of the system. The paper suggests evolutionary computations as a solution for the route planning problem because this approach enables to perform multicriteria optimization of a set of solutions simultaneously. For autonomous ship handling and seaworthiness control, the paper suggests machine learning techniques because these techniques can solve problems in case of uncertainty and the environmental mutability. For inter-ship communications, the paper suggests distributed consensus algorithms, widely used in parallel and distributed computation systems. To ensure the onboard control system robustness, the paper suggests the actor approach that represents that the entire software system consists of a set of elementary agents communicating in the distributed computational environment.