MARBLEHEAD – A paraplegic Marblehead woman and her disabled sailing partner from California are in the lead after two days of Paralymics racing in China.Maureen McKinnon-Tucker and Nick Scandone, the only team representing the U.S. in the 18-foot SKUD sailboat class, completed a second day of racing on Tuesday and were slated to rest Wednesday.According to McKinnon-Tucker’s husband, Dan Tucker, who has been in Qingdao to witness the regatta and assist the SKUD team, the U.S. boat is in first place in the race for a gold medal, followed by Australia and Canada.McKinnon-Tucker, 42, was partially paralyzed at age 30 when she fell from a sea wall. Scandone, the skipper, suffers from Lou Gehrig’s disease.Since every boat in the competition hails from a different country, there’s no need to put a number on the sails. Instead, the boat sailed by McKinnon-Tucker and Scandone has a racing sail or kite designed as an American flag.Dan Tucker watched the regatta from a spectator boat in the bay. “When we got out to the racecourse, the Stars & Stripes was leading by a healthy margin and finished first,” he said in an email Tuesday.