SWEEPOP is a flexible model that simulates the physical interaction between objects in a maritime underwater environment. The model was built to analyse the deployment and the performance of a Target Simulation Mode (TSM) minesweeping system for the Royal Netherlands Navy (RNLN) and to support its procurement. SWEEPOP is a part of MOSES, the TNO Maritime Operations Simulation and the Evaluation System. MOSES supports the evaluation and validation of systems, concepts and tactics in the field of underwater warfare. SWEEPOP uses tools and services from MOSES. SWEEPOP calculates the propagation of the signature, created by a ship or a sweep, through the water and its influence at the location of the threat. The current version of SWEEPOP contains advanced magnetic, acoustic and electric propagation and inversion models. Other influences and new models can be added. The paper describes how a combination of detailed physical models and simulation techniques can be used to give operational advice to the Navy.