The Rihtniemi- class boats were built on Rauma Repola OY between 1956 and 1957 . The two units initially used as mine layers by the Finnish Navy are the first construction lot / a sub-class of the R-Class, which later comprised five boats.
The boats were converted into patrol boats in the course of their use in Finland and remained in service with the local navy until 1999. Then they were taken over by the Estonian Navy and operated by them until 2005.
After retiring from active naval service in 2005, one of the two boats, the Suurop , was handed over to the Estonian Maritime Museum and laid up in the Tallinn seaplane port . The other boat, the Ristna , was operated as a school and museum ship by the Naval Division of the Estonian Defense Association. She was still functional for a few years and made occasional visits to coastal cities. It has also been in the seaplane airport since 2015.
