He competed at the 2014 World Rowing Championships in Bosbaan, Amsterdam, where he won a silver medal as part of the coxed pair with Scott Durant and Henry Fieldman.

He was part of the British team that topped the medal table at the 2015 World Rowing Championships at Lac d'Aiguebelette in France, where he won a bronze medal as part of the coxless four with Scott Durant, Tom Ransley and Stewart Innes.

[3] He also competed in the men's coxless pair event at the 2016 Summer Olympics finishing fourth in the Final.

[4] He won a bronze medal at the 2018 World Rowing Championships in Plovdiv, Bulgaria, as part of the eight with James Rudkin, Tom Ransley, Thomas George, Moe Sbihi, Oliver Wynne-Griffith, Matthew Tarrant, Will Satch and Henry Fieldman.

[7][8] Sinclair was the Match Director for the inaugural Home International Rowing Beach Sprints in August 2022.