Her eighth war patrol (commanded by Harry Hull, Class of 1932), lasting 4 April to 23 May 1943, was uneventful, but her ninth saw the boat score another kill. Off Balikpapan, Borneo, she sighted a three-ship convoy, escorted by a sole destroyer ("Hokaze") on the night of 30 June 1943. After an unrewarding try with a trio of torpedoes, "Thresher" dodged the escort's depth charging attack and returned for another attempt. Tracking with radar, "Thresher" set a tanker ablaze from stem to stern and scored hits on a 5,274-ton passenger freighter in the Makassar Strait.