One man was hospitalized Wednesday after two yachts burst into flames and sank in Manhasset Bay off Long Island’s Port Washington, authorities said. The fire fully engulfed a 43-foot Marine Trader boat at Manhasset Bay Marina in the wee hours of Wednesday, then spread to a 42-foot Post boat in an adjacent slip, the Port Washington Fire Department said in a statement. A 58-year-old man was aboard the Post boat, authorities said. Responders from several agencies rushed to the scene “in single-digit temperatures” at around 12:30 a.m. Wednesday in the Village of Manorhaven, the fire department said. Two hoses were extended about a thousand feet to the end of the marina in a two-hour battle to extinguish the flames and protect the surrounding dock and boats. A fire department marine unit was “able to secure one of the boats as it drifted out of the marina,” the department said. “Both boats eventually sank.” The boat the fire originated on was empty, but the man from the neighboring boat was taken to a local hospital with smoke inhalation and burns, the department said, noting, “There were no other civilian or firefighter injuries.” The fire was under control by 2:15 a.m. and everyone had been dismissed by 3 a.m., authorities said, thanking the eight agencies that had responded to the dead-of-night blaze. The Nassau County Fire Marshall, Arson Bomb Squad and Marine Bureau were investigating the incident. The owners of the two yachts were not identified.