Sinclair was born in Laguna Beach, California and played water polo at Newport Harbor High School.
At Newport Harbor, he won the CIF Championship in 2000 and was twice named Sea View League Most Valuable Player in 2002 and 2003.
[7] He signed with Hunter Hurricanes of the Australian National Water Polo League and played in his first match on January 24, 2008.
[18] Sinclair was named head girls' water polo coach of Corona del Mar High School in May 2013.
[19] Sinclair was named head boys water polo coach of Newport Harbor High School in 2015 Sinclair was named head girls water polo coach of Newport High School in 2018 after Brian Melstrom's announced retirement shortly after winning Division II against Santa Barbara.