Sime started sailing when he was 7 in Optimist class. He entered the Optimist national team in 1998. Three years later he started sailing with his friend, Igor Marenic from the Optimist National Team. Since then the duo have won three Junior World Championships, a Junior European Championship, Senior World and European Championships, and many other international medals. Sime and Igor competed in the 2012 Summer Games, placing 6^th, they are out on the water every day looking to do even better in Rio.