The first commercial ACV service started with Vickers VA-3 in Britain in 1962. Since 1964 Mitsui (MES) has been making R and D efforts in ACV production and constructed 29 hovercraft of MV-PP series. Recent MV-PP10, a diesel powered 105 passenger hovercraft has achieved high performance and remarkable running cost efficiency. The weight penalty due to the adoption of diesel engines and welded aluminium structures resulted in water drag increase particularly in low speed region. In order to overcome the water scoop, model tests and FEM numerical analyses together with full scale sea trials have been conducted. Full scale measurements with conventional rear skirt systems revealed that the rear skirts would scoop the sea water at about 8 knots. Through the research and development works new rear skirts were conceived and designed for actual use considering geometric instability of the inflated membrane. There were great improvements in the reduction of the drag compared with the conventional systems. Two MV-PP10 hovercraft equipped with the improved rear skirts are now in commercial service for access to Oita airport by Oita Hoverferry Co, Ltd.