This report describes the development of the new Vetus marine toilet concept proposal, the Fix&GO, for the Dutch aftermarket of do-it-yourself small cabin motor yacht owners. The Fix&GO marine toilet combines comfort, cleanability and serviceability in a unique way. It brings comfort into the limited marine lavatory while also providing ease and transparency of installation and maintenance. This Integrated Product Design master graduation project is carried out in cooperation with Vetus N.V. in Schiedam and Delft University of Technology. The challenge of this assignment was to gather market and user data, and apply ergonomics in the design of the marine toilet. Various methods, quantitative and qualitative, are used to come to the final result. The combination of the methods structured in a user centered product development variation of the Pahl and Beitz model is what makes the approach valuable. Two interaction prototype toilet seat studies are preformed to design an ergonomic marine seat.