In the current breakwater design process, not all feasible concepts can be explored due to time constraints. However, designers are also influenced by breakwaters constructed near, or at the same location as their breakwater project. But also conservative assumptions influence the breakwater design process, for instance, regarding the wave height and water depth for which caisson and rubble mound breakwaters are both economical feasible. This results in a suboptimal design, which can result in losing a tender. By developing a design automation tool more concepts can be generated in the same period, allowing designers to explore more concepts during tenders. However, before developing a design automation tool one must first understand the process to be automated. Therefore, interviews with experienced designers have been conducted to investigate how they design, i.e. what is their design approach and how do they generate and select concepts. It appeared that the practical breakwater design approach relies on the experience of designers since engineering judgement and experience were mentioned as the preferred methods for the selection of the most promising concept. Furthermore, the designers described an iterative approach for generating concepts during the conceptual design phase, but they did not explicitly stated that these iterations were part of their design approach, indicating that experienced designers automatically perform the required steps. During the interviews, it also became apparent that implementing a probabilistic design approach is unwanted by designers. According to the interviewees, this results in a too conservative and too expensive design, which can result in losing the tender. They also reported that there is a lack of data, which likely results in the designers making conservative estimates to compensate for the missing data. However, this research did not investigate if conservative estimates are made when data is missing, and therefore requires further research. Based on the interviews a design automation tool was developed which can design rubble mound, caisson, and vertically composite breakwaters. Because of the importance of experience the decision was made to automatically selects concepts. This to give the largest freedom to the designer so that his experience is incorporated in the process, while using the benefits of automation for the quick generation and verification of concepts, resulting in a semi-automatic design process. The developed tool was verified and validated by interviewing experienced breakwater designers. From a document and code inspection, it was concluded that the new tool fulfilled all requirements. During these interviews, the designers stated that they would be able to use the developed tool in their design approach. One of the main advantages of the tool is that it was able to quickly design concepts, 0.14s per concept, and made it possible to explore the influence of parameters on the design and cost. This enabled designers to explore more concepts and assess the feasibility of different breakwater types, and thus enabled them to generate a better design. Therefore, it can be concluded that the developed design automation tool can indeed improve the breakwater design process.