A study has been conducted to characterise the coordination that is required in systems of distributed cognition in the maritime industry. This concentrated particularly on the role of organisational artefacts –entities such as rules, procedures, authority structures, records and so on that have organisational functions rather than physical ones. These artefacts work by providing constraints. Such constraints make the coordination of distributed cognitions more tractable, and they provide other organisational functions in parallel –such as encoding historical learning. An analysis of accidents provided the empirical basis of the study, in an attempt to reveal what was commonly taken for granted in normal operations. The results provide a characterisation of the kind of artefacts involved, the kind of coordinations that are required, and the ways in which this coordination sometimes fails.