PROPULSION: Marine diesel engines developing 3,400 horsepower with electric motors developing 7,200 horsepower to 1 x Shaft astern.
Japan's important position in the Pacific has required it to field a capable naval force. Its modern, powerful surface-going fleet is augmented by its commitment to an underwater fighting force by way of attack submarines. One of the active classes once-available to the Japanese Maritime Self-Defense Force (JMSDF) service was the Harushio-class. These boats, numbering seven in all, were built from 1987 into 1997 and saw commissioning from 1990 into 1997. However, their reign under the high seas was relatively short for the class was decommissioned in full with the retirement of Asashio (SS-589) in February of 2017.
Boats in the class included lead-ship Harushio (SS-583) followed by Natsushio (SS-584), Hayashio (SS-585/TSS-3606), Arashio (SS-586), Wakashio (SS-587), Fuyushio (SS-588/TSS-3607) and Asashio (SS-589/TSS-3601). Decommissioning of the boats spanned from 2009 into 2017.
The group was built to a standard ranging in displacement from 2,500 tonnes when surfaced to 3,200 tonnes when submerged. Early boats were completed with an overall length of 252.6 feet and later ones came online with lengths of 255 feet and 285.4 feet. All of the boats in the class had a beam of 32.9 feet and draught of 25.2 feet. The boats were given low-profile bows and tubular hulls. The fin, or sale, was positioned forward of midships and carried the dive planes. The rudder consisted of a cruciform pattern with a single propeller unit exposed. Drive power was provided for by a diesel-electric configuration feeding the single shaft astern. This arrangement forced the vessel to surface to recharge its batteries for undersea operation. The diesels provided 3,400 horsepower when surface-running and the electric motor made 7,200 horsepower for undersea travel. Surfaced speeds could reach 12 knots while submerged speeds peaked at 20 knots.
The early boats in the series all had crews numbering 75 while SS-589 fielded around 70. Installed systems included the Hughes/Oki ZQQ 5B hull-mounted sonar system and the ZQR-1 series towed sonar array. A JRC ZPS-6 I-band made up the search radar fit. Armament was 6 x 533mm (21") bow-facing torpedo tubes with 20 reloads carried. The vessel could also fire the UGM-84 "Harpoon" American-designed anti-ship missile as required.
Lead-ship Harushio (SS-583) was laid down on April 21st, 1987 and launched to sea on July 26th, 1989. She was formally commissioned on November 30th, 1990 and led a rather quiet service life until decommissioned on March 27th, 2009.
Natsushio was introduced in March of 1991 and operated until March of 2010. Hayashio served from March of 1992 until March of 2011. Arashio followed in March of 1993 until March of 2012. Wakashio operated from March of 1994 until March of 2013. Fuyushio served from March of 1995 until March of 2015. Asashio, the last of the class in every regard, was commissioned on March 12th, 1997 and served actively until February 27th, 2017. She was converted to a training submarine in March of 2000 and redesignated as TSS-3601. She was then converted, once again, to a test submarine in April 2002 before the end arrived for the boat.
Likewise, Hayashio and Fuyushio were both converted to training subs (March 2008 and March 2011, respectively) before the end of their days.
Natsushio, Hayashio, Arashio and Asashio carried the names of former Imperial Japanese Navy (IJN) destroyers of the World War 2 period (1939-1945).