Russia took a chance in 2016 when they built the first arctic patrol ship that combined the capabilities of a Krivak III class frigate and a light icebreaker. This ship, the Okean, is a 2,700 ton vessel that can handle thin, as in about 80mm (three inches) of ice and survive heavier ice. This is less than the older militarized Susanin class icebreakers they were replacing. It was found that during patrol operations Susanin rarely faced the heavier ice that they were built to handle.
So the Okean was designed with that in mind. This ship has a top speed of 39 kilometers an hour and a crew of 44 that can stay out for 60 days. Armament is one 76mm gun and two heavy (14.5mm) machine-guns. There is a helicopter pad and a hanger for a Ka-27 helicopter. The first Okean was assigned to the northern Russian coast, where most Russia naval bases are located. The second one, which entered service at the end of 2019 was sent to the Pacific Coast, where is actually more smuggling and other coastal criminal activity during ice season. A third Okean will enter service in mid-2020 and two more are planned.
Previously the only ships Russia had for patrolling ice infested waters were eight Ivan Susanin class arctic patrol ships that were basically militarized versions of the eight Dobrynya Nikitich/Susanin class icebreakers built in the 1960s. In the 1970s eight more of these were built but modified to serve as arctic patrol ships. Most of these have been retired or were close to it. The resulting Nikitich class were 3,000 tons displacement and sturdy enough to break up the 200mm (eight inch) thick ice found around many arctic ports. Larger icebreakers handled thicker ice in areas where the coast guard was not likely to find any illegal afloat activities. Russia also built eight Krivak III frigates as coast guard patrol ships in the 1980s and early 1990s. These could not handle ice at all and were used to supplement the Susanins in northern areas when the coast was ice-free. All these patrol ships were operated by the secret police (KGB then, now the FSB) where ice was a problem along Russia’s northern coast (east of Norway) and in the Pacific (north of North Korea). In both areas there was and is some criminal activity along the coast which continues into the ice season when experienced local mariners would, for a high enough fee, assist in smuggling operations when the coastal waters were full of ice. These older arctic patrol ships were armed with one or two 76mm guns, one or two 20-30mm autocannon and some heavy machine-guns. Crew size was about 80, top speed was a 25 kilometers an hour and endurance a month or two. There was a helicopter pad but no hanger, so the Susanins could not carry a helicopter with them while on patrol.