During the Master thesis work the switching of a diesel 2-stroke marine engine into a dual fuel one was assessed. As the project was carried on at LAV (Labor für Aerothermochemie und Verbrennungssysteme), at ETH Zürich, in collaboration with the Winterthur Gas & Diesel AG company, we were required to focus our analytical study above all on the combustion process of one of the RTX-5 engine cylinders: by applying a LES (Large Eddy Simulation) approach, we took advantage of the FGM (Flamelet Generated Manifold) combustion model and went on making a comparison between the results obtained by means of the above mentioned model, which was used at LAV, with the one taken into account by the Winterthur Gas & Diesel AG company, the PV (Progress Variable) model..