A further development of the Project 670 class (ASCC/NATO codename Charlie I), of which 11 were constructed, the Project 670M class (also known as ‘SKAT-M’; ASCC/NATO codename Charlie II) was an SSGN of which only six were constructed, all in Gorkiy, between 1973 and 1980. The powerplant consisted of one VM-4 water-cooled reactor (89.2MW) and its length was 103 metres. Displacing 4,372 tons when surfaced and 5,500 tons submerged, they were capable of reaching maximum speeds of 20 knots on the surface and 24 knots submerged. While the weapons systems of the Project 670 class included eight P-70 Amethyst anti-ship missiles, the improved Project 670M-class vessels included an 8-metre insert in the hull forward of the sail, incorporating electronics and launch systems for targeting and firing eight P-120 Malakhit anti-ship missiles. Secondary armament included six 533mm torpedo tubes with 12 reloads (of which two were usually Tsakra nuclear anti-submarine torpedoes). Boats of this class are known to have undertaken only 38 patrols in the Atlantic and the Mediterranean, indicating low serviceability rates. All were scrapped between 1990 and 1994. (Artwork by Ivan Zajac)