Disruptive technology is affecting all industries and shipping is no exception. Commercial autonomous ships are soon to be realised but before they can operate internationally, there are significant legal hurdles to overcome. This article considers some of these hurdles from a common law perspective. First, the lack of human presence on-board may render the proposed autonomous ships unseaworthy thereby removing the benefit of the exclusions in the Hague and Hague-Visby Rules and potentially voiding marine insurance policies. Second, these ships may not be able to comply with COLREGs. Third, the traditional role of the shipmaster will disappear and the associated legal duties and liabilities will disperse to other actors. Finally, compulsory pilotage laws vary not only from country to country, but also from port to port meaning that autonomous ships may not be permitted to berth in some ports. Thus, their usefulness as cargo-carrying vessels will be limited unless these issues are resolved at an international level.