Innovative design concepts for the yachting market: expedition yachts and electric propulsion

In the last years a new type of ship has appeared in the superyacht market: the expedition yacht. It is an innovative luxury vessel with specific technical characteristics enabling for a navigation in both tropical and harsh climates. Such an operative profile obliges to fit up equipments that need to work efficiently in very different conditions, and consequently with very dissimilar power requirements. Dimensionally, expedition yachts are in general between 30 and 45 m long. Their exterior reminds working boats such as supply vessels, ocean tugs or whaling ships, but their interior fittings and furniture are definitely luxurious. Moreover, this type of yacht must assure environmental friendly technologies, that is to say, for instance, reduced gas emissions (COx, NOx and SOx), no water/oil pollution, and low noise and vibrations, along with an extended range. In order to conveniently meet such different needs, electric propulsion system can be considered a rational solution. In fact, the significant increase in the hotel and auxiliary power – that is almost of the same order of the propulsion power at cruising speed – justifies the adoption of multiple generating units driven by small diesel engines, in case also different in size. So, the number of running generating units can be selected in such a way as to have an optimum loading on each engine, in accordance with the current operative mode of the vessel. As a design example, all-electric concept is exposed taking into account a specific project of an expedition yacht. In this project, azimuthing electric podded drives are adopted to enhance the characteristics of manoeuvrability and dynamic positioning. For such a vessel the general arrangement plans as well as the layout of the integrated electric power system are shown.