Complex sentence: From the Yale Corinthian Yacht Club and relying on the boat "Courageous" who won the America's Cup in 1974 and 1977, the boat had been heavily redesigned and updated to make her more competitive for the 1987 campaign.
Split into simpler sentences: From the Yale Corinthian Yacht Club, sailing "Courageous", winner of the America's Cup in 1974 and 1977. The boat had been heavily redesigned and updated to make her more competitive for the 1987 campaign.