Mirna-class (Type 171)

The Mirna class, also designated as Type 171, is a series of eleven patrol boats built by Tito's Kraljevica Shipyard in SR Croatia. Developed as a replacement for the earlier Type 131 boats, the class was completed between 1979 and 1985 for service in the Yugoslav Navy Maritime Border Brigade.

The design features a steel hull divided into seven watertight compartments and an aluminum alloy superstructure. While primarily intended for maritime border patrols, the class is equipped for anti-submarine warfare (ASW). Detection capabilities include a Simrad SQ3D/SF sonar and a Decca RM 1216A navigational radar. For ASW operations, the vessels can be outfitted with depth charges. The standard crew complement consists of two officers, five junior officers, and fifteen sailors.

During the Croatian War of Independence in 1991, several units were involved in naval engagements. PČ-171 was damaged by a 9K11 Malyutka missile off Škarda, while PČ-176 was struck by an improvised torpedo in the Dalmatian Channels. Both vessels, along with two others captured at the Šibenik Shipyard, were incorporated into the Croatian Navy. The four boats remain nominally in Croatian service, though Šolta was declared surplus and offered for public sale in April 2025. The class is being replaced by the Omiš class, the second of which, Umag, entered service in January 2025.

The seven remaining vessels were relocated to Boka Kotorska to serve in the Navy of FR Yugoslavia. These units were decommissioned in the early 2000s. Two were transferred to the Ministry of Interior for use by the naval police before being sold for scrap in 2012. The other five units were sold to private owners and converted for use as civilian tourist vessels.