Automation is projected to transform many industries and work domains and enable both increased levels of safety and efficiency by reallocating many of the functions traditionally performed by operators. However, research on the relation between automation and work practice is lagging and needs to be further explored in order to ground the debate and design of automated work on a sound empirical basis reflecting work in actual organizational settings. In particular, research is needed that offers rich naturalistic representations of human automation interaction that accounts for the mutual shaping of human and material agency over time. The ethnographic workplace study reported in this paper draws on the sociomaterial practice perspective and on the theory of imbrication to analyze a case in which an automatic speed regulation system was installed onboard five large passenger ferries in order to improve the energy efficiency of the execution of voyages. The results show how the adoption, appropriation and use of automated technologies is inextricable from the local patterns of social interaction and collaboration. The study contributes with a deeper understanding of the relation and entanglement of the social and technological elements in human automation interaction. © 2020 Elsevier Ltd