As a result of the rising levels of emissions and global warming, coupled with the escalating world population and energy demands, the International Maritime Organization (IMO) has implemented stringent regulations for ships. Enhancing energy efficiency in maritime vessels can be accomplished through the utilization of an organic Rankine cycle (ORC) powered by the waste heat from marine generator sets (gensets). This research specifically focuses on toluene, R600, isopentane, and n-hexane, chosen as dry fluids for their role as working substances. The study involves the computation of cycle and exergy efficiencies, net power output, and irreversibility for both marine genset exhaust-driven simple cycles and those equipped with a recuperator. Since all organic fluids used in the study are included in the same safety group (A3), ozone depletion potential (ODP), and global warming potential (GWP), these parameters were not considered when choosing between fluids. In this study, the optimal fluid for low turbine inlet temperatures is found to be n-hexane, while for high turbine inlet temperatures, toluene exhibits the highest efficiency. For a turbine inlet temperature of 200 °C, n-hexane has a cycle efficiency of 37%, exergy efficiency of 60%, net power of 135.714 kW, and irreversibility of 145.486 kW at full load of the marine genset. For a turbine inlet temperature of 300 °C, toluene has a cycle efficiency of 41%, exergy efficiency of 63%, net power of 140.727 kW, and irreversibility of 150.817 kW at full load of the marine genset.