We present a systematic investigation of the velocity fields of both isolated and interacting spiral galaxies in combined N-body/hydrodynamical simulations. Closely mimicking the procedures applied in observations of distant, small, and faint galaxies we extract rotation curves (RCs) and compare the results of the simulation directly to observations. Irregularities in the velocity field reflect disturbances in the gravitational potential of the galaxy. They can be used to trace the recent interaction history of a galaxy and give possible clues to the type of the respective interaction. In addition, identifying disturbances in the RCs is important for Tully-Fisher studies in order to accurately derive the maximum rotation velocity.