By 2040, the Port of Rotterdam Authority (PoR) intends to replace its fleet with vessels that do not emit greenhouse gases and are modernised. Replacing the entire fleet also presents an opportunity to review and improve the operational processes and the equipment used. This is a complex challenge due to the following three factors: (1) the high number of stakeholders complicating the decision-making process, (2) risk aversion in modifying current business operations due to a lack of clarity regarding the impact of decisions, and (3) the challenge of determining what is feasible while also meeting the expectations of all stakeholders.

The PoR expressed a need and interest in becoming familiar with more scientifically based decision-making methods to help them achieve their ambitious goal. The method should facilitate improved decision-making for complex choices and should consider how the impact of different choices will be made visible, allowing users to explore various fleet combinations regarding the system performance.

Therefore, this master's thesis aims to develop a decision-support tool based on the Preferendus Methodology (from \cite{zhilyaev_best_2022, van_heukelum_socio-technical_2024}), a state-of-the-art approach specifically designed to bridge the gap between what is 'desirable' and what is 'feasible'. By doing this they tool facilitates the finding of the best 'fit for purpose' renewed fleet composition.

This Master's thesis demonstrates the successful development of a 'Preference Based Idealized Design tool and methodology that integrates the Preferendus and Idealised Design methodologies. The tool and methodology are conceptually tested at the Port of Rotterdam for their Fleet Renewal Challenge. The tool facilitates the finding of a solution that is both ‘desirable’ and ‘capable’ by integrating multiple stakeholders' objectives and preferences into the modelled system. Additionally, by incorporating stakeholder preferences, the tool facilitates transparent collaborative decision-making and the integration of both technical and social aspects.

Furthermore, the tool is developed with object-oriented-programming principles that ensure the maintainability and scalability of the tool. This makes it suitable for extensions and applications at other projects.

Additional research can be conducted by applying the Preference-Based Idealised Design tool and methodology to other projects. Ideally, this would be done with a project team that has fully adopted the methodology. It is particularly interesting to apply this tool and methodology to a project involving organisational issues, as the Idealized Design approach is designed for organisational redesign.