Graceful, the latest yacht from the Hamburg shipyard Blohm + Voss, will arrive at the end of the year, boasting an indoor pool that measures nearly 50 feet by 10 feet and can be converted to a dance floor by raising the pool floor. The 269-foot yacht—which can reach a maximum speed 17.6 knots—was designed by the London-based H2 Yacht Design to feature a separate owner’s area with a duplex suite and a balcony that folds out to the sea, in addition to two VIP suites and three guest suites that can sleep 10 addit…