Within a shipyard, many designers each having their own design objective cooperate in a complex design situation where a variety of software tools run on different hardware platforms. The exchange of design data models among these heterogeneous CAD systems is a difficult task because the systems involved have different data structures optimized for their own functions. CAD geometric models are represented by different schemes such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. A data exchange usually requires topological modifications of CAD data. This paper presents a strategy of CAD data enhancement for the purpose of data exchange that includes topological changes of geometric models. As a practical example, a shipbuilding product model with shipbuilding features is implemented according to the STEP methodology. Its geometric data is enhanced through a non-manifold modeler to a data set valuable to downstream applications such as a FEM solver or a detail design system. The ACIS modeler that supports a non-manifold data structure is used for low-level geometric operations. (C) 1998 Elsevier Science Ltd. All rights reserved.