While the integration of Geographical Information Systems (GIS) and Mul- ticriteria Decision Aiding (MCDA) has attracted increasing interest from re- searchers in recent years, due to the wide array of applications that can benefit from GIS as well as the different types of decision problems and various models that can be used through MCDA, plenty of opportunities of integrating GIS and MCDA remain. In this paper we present the result of such an opportunity in the form of a methodology and a software that is currently used by the Naval Hydrographic and Oceanographic Service in France. Furthermore, this tool may be used in conjunction with other GIS-MCDA applications with a single decision maker, multiple decision makers or even where the decision has a hierarchical structure.