Saving energy and money is one of the main concerns of many industrial and service firms. Reducing energy consumption means reducing environmental impact, related to the considered activity, and in some cases this entails also economical benefits. Environmental impact reduction becomes of main importance if the device operates in a nature reserve.In this work the possibility to install a micro-cogeneration system has been studied, for a small passenger vessel, by recovering a fraction of the heat rejected by the existing, fossil-fuelled, on-board engines, instead of the actual auxiliary fossil-fuelled heating system. These systems are necessary for supplying thermal demands to the pilot cockpit and to the passenger cabin, during the cold period of the year. The boat operates on a lake, “Trasimeno”, that belongs to an Italian nature reserve.Thermal features of the boat structure have been carefully examined and evaluated. Experimental analysis of the amount of heat and temperature available from the engine has been carried out with the aid of a thermocouple and a non-intrusive ultrasonic flow-meter. The heat recovery system was designed and the capital cost estimated.An environmental and economical benefit analysis was also carried out.