The International Maritime Organization (IMO), the United Nations body that writes shipping safety rules, adopted the first code for Maritime Autonomous Surface Ships (MASS) on 22 May, closing its Maritime Safety Committee (MSC) 111 session in London.1 A MASS is a cargo vessel that senses, decides and steers with a reduced crew or none aboard. The code enters force on 1 July 2026, applies to cargo ships only, and keeps a human master legally responsible even when that master sits in a control room ashore.
The small print blunts the milestone. The code is non-mandatory until a binding version targeted for 1 January 2032, and the years between open an Experience Building Phase in which flag states collect operational data and decide for themselves what to permit. The Experience Building Phase exists because no regulator yet holds enough crewless-voyage data to write binding rules. The gap is a data-collection device, but it also lets national regimes diverge.
Classification societies already run ahead of it. DNV and Lloyd's Register, the bodies that certify ships as safe and seaworthy, certify autonomous and remotely operated vessels under their own rules today.2 That inverts the usual order: SOLAS safety rules normally precede the technology, whereas here the IMO is racing to catch up to commercial practice. The risk is a patchwork of national interpretations during the gap, plus a new shoreside regulated entity, the Remote Control Centre, whose liability questions the code defers rather than settles. Nautilus International, the seafarers' union, argues the master should stay aboard while any crew are present, a labour counterweight to the cost case for emptying the bridge.
The same autonomy stack that runs a crewless box ship runs a minehunter and a subsea-cable inspection drone, which is why a shipping safety code matters to a defence procurement reader.
