Currachs are traditional boats, made of thin strips of wood, covered in cloth, but their use has declined in Ireland since the 19th century. When traditional practices need reviving or maintaining, ethnomathematics is often promoted as a way to contribute to this in mathematics classrooms. In this paper, we use the cultural symmetry model to examine opportunities and issues that could arise when ethnomathematics is used to explore the building of currachs. We investigate this as a research project, with potential links to what could occur in school. This model enabled us to discuss how the currachs used locally available materials to fulfil specific purposes and to consider how describing them as mathematics could add to understanding their construction. The model also provided opportunities to discuss how the design of currachs and why they are no longer being built in many places can be connected to the valuing of different knowledge over time.