Complex sentence: The event is followed on the Sunday by the Edith Topsfield Junior Regatta (ages 7 to 16), which was founded in 1932 and former winners of this regatta have gone on to become Olympic medalists.
Split into simpler sentences: The event is followed on the Sunday by the Edith Topsfield Junior Regatta for young people between the ages of seven and sixteen. This was founded in 1932 and former winners of this regatta have gone on to become Olympic medalists.