William Carl Buchan (born December 23, 1956) is an American sailor and Olympic Champion. He won the ICSA Men's Singlehanded National Championship and was named College Sailor of the Year in 1977. He competed at the 1984 Summer Olympics in Los Angeles and won a gold medal in the Flying Dutchman class. He sailed for Stars & Stripes when they defended the 1988 America's Cup. His father William E. Buchan won a gold medal in the Star class at the 1984 Olympics and 11 medals at the Star World Championship. Carl attended Mercer Island High School in Mercer Island, Washington.