Complex sentence: In 1968 he was the third of 9 sailors who attempted to achieve a solo non-stop circumnavigation of the world in the Sunday Times Golden Globe race, and the only one to complete the voyage.
Split into simpler sentences: In 1968 he was one of 9 sailors who attempted to achieve a solo non-stop circumnavigation of the world in the Sunday Times Golden Globe race. He was the third sailor to start the race, and the only one to complete the voyage.