Again coming to periscope depth at 17:00, "Thresher" soon sighted a four-ship convoy at with a single sub-chaser as escort. Surfacing at 19:11, "Thresher" began the chase, tracking the convoy by radar. The three leading targets steamed in column, with the escort between the third and fourth merchantmen. "Thresher" maneuvered to the west to silhouette the targets against the rising moon. The convoy changed course at 21:55, giving "Thresher" an excellent setup for her stern tubes. At 22:07, the boat let fly from with four torpedoes at the lead ship, a 6,960 ton freighter. "Thresher" observed two hits, and the vessel, its bow in the air, was observed in a sinking condition.