Synthesis 66 is a 42.37-meter motor yacht built by the renowned Dutch shipyard Feadship and delivered in 1982. With a beam of 7.9 meters, a draft of 2.5 meters, and a gross tonnage of 347 GT, she blends timeless Feadship lines with robust engineering and refined interiors. Previously known under several names including Centinela IV, Halcyon, and Spellbound, Synthesis 66 showcases exterior design by De Voogt Naval Architects, with interiors by Larvor and Boutsen Design. She accommodates up to 10 guests in comfort and elegance, along with space for 9 crew members including the captain. Built with a steel hull and aluminium superstructure, she is powered by twin Caterpillar engines, delivering a cruising speed of 12 knots and a top speed of 13 knots. Her range is 3,500 nautical miles at 12 knots, supported by fuel capacity of 44,000 liters and fresh water storage of 10,000 liters. Ranked 2,446th among the world’s largest yachts and the 174th-largest Feadship ever built, Synthesis 66 remains a proven and well-maintained classic. She underwent her latest refit in 2024 in Spain and is currently offered for sale at €16,500,000.