ACV aerodynamic aerodynamics air air-cushion air-cushion-vehicle air-pressure amphibious craft cushion drive engines fans flexible flexible-skirt flight friction high-air-pressure hovercraft hull hybrid-vessel impeller inflated inflated-skirt low-frictional-force MTV multi-terrain-vehicle multiple-terrain on-board pilot propel propellers rise sightseeing skirt skirted specialised-transport speed stationary surface surfaces thrust tourism tourists transport transporting travel travelling vehicle air-controls amenities bubbling high-volume hot-tub hot-tub-spa hydrotherapeutic-massage hydrotherapy jacuzzi jet-technology jets jetted-whirlpool large-tub low-pressure massage massage-jets outdoor outside pump-system pumps sanitized sanitizing small-pool spa spiraling swirl swirling warm warmed water waterfall whirlpool