Grillage design is one of the most common tasks in ship structural engineering, as many components of a ship’s secondary structures, such as hatch covers and decks, are grillages. This paper presents the current state of development of D3V-SGD, an open-source software tool for the design and analysis of ship grillage structures developed by students and researchers from UNIZAG FSB. Realized as an extension module to D3V, an open-source 3D Modular Viewer in Python, D3V-SGD currently features a parametric model for hatch covers, a GUI with 3D visualization, and automatic generation of analysis models for determining structural responses. These models include both grillage beam analytical methods and FEM using shell elements. For FEM analysis, the open-source program OOFEM has been utilized, recently adopted for the analysis of ship thin-walled structures.