In 1767 he married Marie Élisabeth Catherine Boucher de la Boucherie, a daughter of a captain of troops in the service of the French East India Company.

Attached to the French East India Company at Lorient, he designed ships suitable for combat and commerce; among them the Duc de Duras that later became the famous American frigate Bon Homme Richard.

Promoted to chief constructor in 1769, he was put in charge of building the docks of Toulon, solving the difficult technical problems involved.

In 1782 Groignard was promoted to constructor general with the rank of post-captain, working on the docks at Brest putting them in condition to receive the largest ships of the Navy.

In 1765, he won a prize from the Marine Academy with a memoir on the stowage of ships: "Mémoire sur l'arrimage des vaisseaux".