Having reached Pearl Harbor on 26 July, Apogon was dry-docked. Both tail shafts were replaced and realigned, and the periscope, periscope shears, and the radar masts were replaced. The three main engines were also overhauled. On 12 September, Apogon was underway on yet another wartime patrol. She headed for the Kuril Islands area. The submarine then sunk a Japanese patrol craft on 23 September the 400 ton Choyo Maru No.6.Uboat forum Four days later, she sank Hachirogata Maru. Following this sinking, she rescued two Japanese survivors. The next month proved fruitless, and Apogon arrived at Midway on 28 October, ending her fifth patrol.
