Evidence from more than 40 000 voyages shows that labour productivity growth for sailing ships in the London coal trade was rapid but quite irregular between 1700 and 1860. These granular data permit us to examine various dimensions of change, showing that ships made more voyages per year, had smaller crews, carried more coal per ship ton and had longer working lives. Some changes resulted from what happened on land rather than on the sea, notably a marked reduction in the seasonality of trade as wagonways were built in the northeast in the early eighteenth century and a pronounced dip in voyages per year due to congestion in the port of London during the 1830s and 1840s, partly caused by the operation of the coal cartel. These results for the coal trade suggest that shipping, being neither spectacularly modern nor doggedly traditional, made a respectable contribution to British economic growth.