Japan Maritime Self-Defense Force (Kaijō Jieitai) published on its facebook account that the midshipmen are conducting RUR-5 ASROC anti-sub rocket firing exercise and ship-to-ship transport training, aboard JS Setoyuki (TV-3518) and JS Shimayuki (TV-3513) to learn necessary knowledge and skills as Maritime Self-Defense Force officer during the Training Cruise. JS Setoyuki and JS Shimayuki, 130 meters long and 13.6 meters wide, were built originally as destroyers under the Hatsuyuki-class destroyer but were turned into training vessels.
The RUR-5 ASROC (for “Anti-Submarine ROCket”) was an all-weather, all sea-conditions anti-submarine rocket system. Developed by the United States Navy in the 1950s, it was deployed in the 1960s, updated in the 1990s, and eventually installed on over 200 USN surface ships, specifically cruisers, destroyers, and frigates. The ASROC has been deployed on scores of warships of many other navies, including Canada, Germany, Italy, Japan, the Republic of China, Greece, Pakistan and others.
After a surface ship, patrol plane or anti-submarine helicopter detects an enemy submarine by using sonar or other sensors, it could relay the sub’s position to an ASROC-equipped ship for attack. The attacking ship would then fire an ASROC missile carrying an acoustic homing torpedo or a W44 Nuclear Depth Bomb onto an unguided ballistic trajectory toward the target. At a pre-determined point on the missile’s trajectory, the payload separates from the missile and deploys a parachute to permit splashdown and water entry at a low speed and with minimum detectable noise. Water entry activates the torpedo, which is guided by its own sonar system, and homes in on the target using either active sonar or passive sonar.
The Hatsuyuki-class destroyer (Hatsuyuki-gata-goei-kan) is a class of destroyer, serving with the Japan Maritime Self-Defense Force. It was the first class of first generation of general-purpose destroyers of the Japan Maritime Self-Defense Force, combining the anti-aircraft capability of and the anti-submarine capability, while also capable of operating missiles and helicopters. Four ships of this class have been re-purposed as training vessels: JS Shimayuki (1999), JS Shirayuki (2011), JS Setoyuki (2012) and JS Yamayuki (2016). These ships have been converted for training, yet they still have their weapons systems intact. They are referenced after the lead ship as the Shimayuki-class.