Within the scope of the Royal Netherlands Navy’s Walrus class replacement programme, DMO embarked in 2015 in developing a set of tools to generate and assess submarine concept designs. MARIN took up the challenge to develop a design workflow SUPREME on the basis of its Quaestor3 knowledge engineering framework [van Hees 1997, 2003, 2009]. Within this workflow a number of proprietary and often confidential tools should be plugged in to perform e.g. propulsion system dimensioning, weight estimation and for assessment of trimming and compensation capabilities. These ‘satellite’ tools are mostly developed for, or by, DMO. As a design system, SUPREME becomes fully operational at DMO where workflow and proprietary tools come together. The developmental focus of MARIN is the SUPREME workflow which deals with design knowledge representation and design data management. The two major challenges in its development were the topological representation and the weight management methodology. This paper will discuss the first one, the development of a submarine topological representation using the CAD system RhinocerosTM as externally controlled geometry generator. This combines high accuracy with adaptability and enables naval architects to constantly monitor the weight and volume balances and trimming / compensation capabilities of concept submarines already in the earliest stages of design.