The old S boats carried Mark X torps with contact detonators.
Source, GUADALCANAL..Richard B Frank
http://www.microworks.net/pacific/ships ... /index.htm
"Until then, however, some successes had already manifested. While US submarines proved ineffective at defending the Philippines, in the Solomons, the old S-class submarines and their Mark X torpedoes, still relying on the low-tech but effective contact exploders, sank several enemy ships, including the Heavy Cruiser Kako. In the later years, the submarines managed to sink quite a few capital ships, including carriers Shokaku and Taiho, battleship Kongo, and auxilliary carrier Shinano, which remains the largest warship ever sunk by submarines. "






