Since 1987 sonar performance modelling is developed at TNO Physics and Electronics Laboratory. This is based on propagation modelling in a given environment together with modelling of the sonar based on its specific parameters. Beam forming, pulse type and signal processing are taken into account. The ray based model computes reverberation and echoes per eigen ray versus arrival time. Since some years this performance modelling method is extended to torpedo sonars possibly with doppler sensitive or with wide band pulse types. The performance of the latter pulse type is evaluated within the TNO Physics and Electronics Laboratory MOSES testbed in which the performance model REACT is implemented. Also an (acoustic) snapshot program is developed that monitors which signal levels are received in the different beams are after each emitted pulse on the torpedo track in MOSES. Some results of the snap shot program will be analysed in the case of a simple multi high light target under different aspects. The modelled received beam levels form the basis of the modelled torpedo logic applied during search, homing and lockon, and re-attack. The possibilities of wide band signals for slow moving or zero speed targets in shallow water will be demonstrated.