Offshore construction vessels produce significant greenhouse gas (GHG) emissions, which led to the need to understand how operational decisions can mitigate their environmental impact. This thesis investigates the link between operational decision making and vessel emissions, focussing on Jumbo Maritime’s offshore installation projects. A mixed methods approach was adopted, which combined quantitative analysis of vessel operational data with qualitative insights from stakeholder interviews. Detailed analysis of daily progress reports, energy system models, and fuel consumption records allowed the quantification of emissions for each operational activity. Meanwhile, interviews with on- and offshore managers showed how factors such as contract requirements and project complexity influence decision-making in practice.
The results identify which activities drive the highest emissions and why. Dynamic positioning (DP) during offshore operations and transits emerged as the major contributor to fuel use and emissions, whereas periods at anchor or in port resulted in minimal fuel consumption. Unplanned downtime, especially waiting on weather and technical breakdowns, contributed substantially to emissions.
Crucially, the study found that certain operational strategies can noticeably reduce emissions without compromising project performance. Key recommendations include using anchoring instead of continuous DP whenever conditions allow, and implementing proactive maintenance programmes to minimise breakdowns and associated downtime. In addition, it is recommended to align contractual terms and planning processes with emission reduction goals to empower crews to choose more sustainable operating modes. By linking day-to-day operational choices with their emission outcomes, this research provides practical guidelines for offshore vessel operators to reduce their carbon footprint while maintaining efficiency and safety.