The human and social dimension of energy efficient ship operation has been recognized as crucial for the mitigation of emissions from ships. The success of future energy management in the maritime sector is, therefore, likely to depend on operators’, managers’ and policymakers’ understanding of how to address the human and social dimension. However, few studies have investigated the nature of the knowledge, skill and expertise required for efficient voyage execution. The paper is based on a qualitative case study identifying and analysing a number of themes related to the acquisition and development of the capability and competence relevant for energy efficient ship handling. The paper argues for the importance of acknowledging collective tacit knowledge and the socio-material context in which such knowledge is developed. It is argued that this perspective can contribute to widening the debate on policy and management of maritime energy efficiency.