A prototype of a tactical decision aid (TDA), COMBIS (COmbined Maritime Background Information System), has been developed by FOI during 2002-2009. The purpose was to construct a tool for demonstration of our modelling capabilities in shallow waters. The tool was developed in the form of a TDA in order to compare our models, functions and concepts with operational TDAs. The strength of COMBIS is:  prediction of acoustic and electric sensor capabilities  visualization of oceanographic forecasts  focus on duel situations with visualized detection- and vulnerability ranges Our recommendation is that COMBIS is used in areas of trial and testing, studies and teaching. Here COMBIS provide significant upgrades compare to operational TDAs and teaching tools. Future development of COMBIS will be in the area of signature management to enhance the understanding of knowing both your own and the opponents' underwater signatures.