Consider the many vessels operating today. At the time of construction, their on-board equipment was not prepared for full instrumentation and detailed optimization of the operation. Nevertheless, these ships generate substantial amounts of data, digital as well as analogue. Ship owners and managers are using the data available through traditional means like noon reports, event reports and engine logbooks. But we observe that a lot of untapped potential still resides in proper quality-assured and analysed data of this kind. Some owners and managers struggle with the business case of retrofitting auto-logging systems on existing vessels, with systems hampered by unavailability, poor data quality and the high costs of retrofitting and maintaining the equipment. Working satisfactorily, torque and fuel flow meters have seen the biggest uptake so far when it comes to retrofits – and for good reason: the information they generate is crucial for performance management and fuel efficiency, and payback tends to be short.