The Parchim-class corvette, Soviet designation Project 1331M, was developed for the East German Navy in the late 1970s, and built by the Wolgast Peene-Werft. The ships were designed for coastal anti-submarine warfare. In case of an all-out NATO-Warsaw Pact war in Europe their prime targets would have been the small U-206 coastal submarines of the West German navy. The first ship, Wismar (now the Indonesian KRI Sutanto), was launched on 9 April 1981 in Rostock, and subsequently another 15 ships were built until 1986. To make production more economical, the Soviet Union agreed to purchase another 12 ships from Wolgaster Peenewerft built between 1986 and 1990, thereby effectively subsidising the East German shipbuilding industry. The ships of the Soviet Navy were named Parchim II by NATO. Though useful as a coastal ASW platform, the Soviet production of the similar but far more powerful made this purchase even more illogical for the Soviet Navy. After German re-unification, some of the former East German ships were used briefly by the unified Germany Navy before all of them were sold to the Indonesian Navy in 1993. The Indonesian Navy extensively refurbished their Parchims, to the point where the refurbishing exceeded the cost of purchase. They are still in service, both in the Indonesian Navy and in the Russian Baltic Fleet. Construction The Parchims were built to replace the obsolete HAI III-class subhunters of the Volksmarine. Because of their displacement, over 800 tons in full load, they were able to leave coastal waters, even in rough weather. Propulsion consisted of three Soviet-designed M 504 56-cylinder diesel engines, a development of the M 503 A fast attack craft engine. The middle engine provided power to a variable-pitch propeller for cruising speed, while the two outer engines served two outer fixed-pitch propellers for boost speed. Total power output was . The ships were constructed with regular (stainless) steel and consisted of ten waterproof compartments. Weapon systems and sensors Air defence For air defence, the ships were equipped with one double-barrel AK-230 30 mm gun and one double-barrel AK-725 57 mm gun. The AK-725 double 57 mm AA gun, designed in 1959, was directed by the ESP-72 fire control system, which received ranging and target bearing information from an MR 103 (NATO codename 'MUFF COB') radar. The MR 103 had a parabolic radar dish, with an optical camera system slaved to it, as a backup system in