As a single skater, Coulthard won the silver medal at the 1977 Golden Spin of Zagreb and the Australian national title during the 1979–1980 season. She finished 28th at the 1979 World Championships in Vienna, Austria, and 24th at the 1980 World Championships in Dortmund, West Germany. Australia elected not to send her to the 1980 Olympics, leading to her decision to switch to coaching.