Kersaint joined the Navy at a Garde-Marine on 25 July 1762. He was promoted to Ensign on 15 September 1771, and to Lieutenant on 5 February 1786.[1]
He served on Heure du Berger from November 1767 to January 1769. [1]
In 1776, he served on the 40-gun frigate Consolante.[1] In June 1778, he transferred to the 64-gun Brillant.[1]
Kersaint married at Isle de France on 3 April 1780.[1]
In June 1782, Kersaint, by then retired from the Navy,[2] departed Brest, captaining the corvette Duc de Chartes. He arrived at Achem on 24 November.[3]
