The Orkan class or projekt 660M (NATO code: Sassnitz class) is series of three fast attack craft of the Polish Navy, in service since 1992.
The original project was prepared by the German Democratic Republic for its navy and was named Project 151, it also received the NATO reporting name "Sassnitz". After the Unification of Germany the three unfinished hulls were bought by the Polish Navy from VEB Peenewerft shipyard in Wolgast and successfully completed by Northern Shipyard in Gdaà Âsk. Two more unfinished fuselage were scrapped in Germany. In total up to nine units were planned by the GDR. Poland developed a similar attack craft design in the 1970s, but the construction was cancelled in 1980 following Soviet Union denial to export the necessary weapon systems, forcing Poland to order Tarantul missile corvettes in the 1980s.
In 2006, Ministry of Defence ordered 36 RBS-15 Mk 3 anti-ship missiles to equip the ships. Since 2007, they carried RBS-15 Mk 2 missiles as interim armament. RBS-15 Mk 3 missiles were first deployed in 2014. Since 2015 Orkan and Piorun underwent a 19-month, mid-life refit.
The lead ship of the class is named Orkan (), while other two ships are Piorun () and Grom (). and were famous Polish destroyers of the Second World War. Orkan was to have been the first destroyer constructed in Poland, but her construction was interrupted by the start of the World War II.