The shipping industry faces escalating pressure to reduce its carbon footprint. International agreements like the Paris agreement and IMO’s targets for net-zero emissions by 2050 necessitate a shift toward sustainable solutions. In response, shipping companies are searching for various ways to reduce the carbon dioxide emissions through energy efficiency or energy transition solutions. Wind-Assisted Propulsion Systems (WAPS) are contributing to the reduction of the fuel consumption and consecutively the carbon footprint by replacing part of the propulsion power required for the ship’s trips. This thesis is structured into three sections. The first section is the literature review, which establishes the foundational knowledge necessary for the study. The second section, the WAPS uptake analysis, leverages data points to quantify the current adoption trends of these technologies. It reveals that while the market of WAPS is currently a niche market, a clear upward trend is evident in the number of vessels being equipped with these systems mainly driven by specific fleet types. The third section presents a case study, a financial analysis involving the retrofit of a Flettner Rotor on a bulk carrier, to assess the financial viability of the investment with two different financial models. A decision support tool that can be utilized in WAPS investment was proposed. The findings underline that the financial viability of WAPS is influenced by key parameters such as the vessel's operational profile (e.g. idle time, EU exposure), the costs associated with the selected WAPS, the selected financial model, the market variables (e.g. fuel price, carbon price), the parameters of each model (e.g. share of upfront cost and savings between the two parties in the PAYS model), and the weather conditions.