This paper examines the measures available to improve operational energy efficiency from the perspective of onboard crew, the barriers associated with implementing those measures and how crew behaviour can be nudged using incentives. A total of 25 semi-structured interviews and subsequent surveys with 42 onboard crew were carried out to gather qualitative information on two main domains: operational efficiency and incentive schemes. In-depth thematic analysis of interviews showed the central and recurring themes such as stakeholder hierarchy, autonomy and accountability, temporal restrictions, profitability and type of charter. Due to the heterogeneity in interview responses on the topic of incentives, online surveys were conducted. The findings of the study show that whilst speed reduction was seen as the single most important measure to optimise, it was also the most difficult to implement in practice due to several barriers. These include contractual obligations, a complex web of accountability and perverse incentives to increase speed. Other measures such as trim–draft optimisation and auxiliary engine load optimisation have smaller efficiency gains but were found to have more potential for increasing implementation through behavioural changes and encouraged through incentives. Both monetary and non-monetary incentives were perceived to be important and going beyond the status quo of incentivising captains so that rewards are shared equitably amongst the crew. Whilst not generalisable, preliminary findings suggest that there is room to consider alternatives to the current approaches on incentives, which do not take advantage of the importance of acknowledgment and recognition, as well as fostering positive interpersonal relationships.
Rehmatulla et al. (2026) studied this question.