Manning the unmanned ship: Is safe manning legislation a bottleneck in the development of autonomous ships?

Legislation is often mentioned as a barrier to the development of autonomous and/or unmanned ships. This paper examines whether the laws on safe manning of ships is currently a bottleneck in a gradual reduction of crew sizes through the analysis of data on safe manning and actual manning for 210 cargo and passenger ships. It is found that most vessels have an actual manning which is significantly higher than the minimum manning required by law. Both safe and actual crew sizes are, as expected, found to increase with increasing ship size but so is the difference between safe and actual manning. The reason why ships operate with a larger crew than required by law is found to be caused by the technical and operational needs of the vessels. Legislation on safe manning is not identified as bottleneck in the development of autonomous and unmanned ships.