The Pohjanmaa class is a series of four multi-role corvettes currently under construction for the Finnish Navy as part of the Squadron 2020 () project. Together with the existing four s, the four new surface combatants will form the backbone of the Finnish Navy from the mid-2020s onwards. They will replace seven older vessels that have been or are due to be decommissioned; the minelayer , two s and four s.
Design
General characteristics
The overall length of the Pohjanmaa-class corvettes will be and the beam . The maximum draught of the vessels will be which corresponds to a displacement of about . With these main dimensions, the new multi-role corvettes will be the largest Finnish surface combatants since the 1930s coastal defence ships and . Each ship will have a complement of about 70 officers and crew. Designed for year-round service in the seasonally freezing Baltic Sea, Pohjanmaa-class corvettes will feature an ice-strengthened hull and ability to operate independently in ice. Although no Finnish-Swedish ice class exists for military vessels, the ice capacity of the corvettes will be equivalent to that ice class 1A for merchant ships.
The Pohjanmaa class will feature a combined diesel-electric and gas (CODLAG) propulsion system with a total output of . During normal patrol operations, the ship's twin ice-strengthened controllable pitch propellers are driven by electric propulsion motors. However, two of the four 12-cylinder MAN 12V175D type diesel generating sets are installed on double resilient mountings within soundproof enclosures to reduce noise and vibration during anti-submarine warfare (ASW) missions. When higher speeds are required, a single General Electric LM2500 gas turbine driving both propeller shafts via a common gearbox can be used to achieve speeds in excess of . For low-speed maneuvering, the ships are fitted with two bow thrusters.
Combat management system, communication system and sensors
The combat management system (CMS) of the Pohjanmaa-class corvettes will be provided by the Swedish defence company Saab. The integrated communication system (ICS) TactiCall is provided by Saab. Built around the 9LV CMS, the system will include Sea Giraffe 4A FF fixed-face AESA and Sea Giraffe 1X short-range 3D radars installed on a Saab Lightweight Integrated Mast (SLIM), two CEROS 200 fire control directors, TactiCall integrated communications system, and a laser warning system. Before final selection, the Finnish Navy shortlisted Saab together with Lockheed Martin Canada and Atlas Elektronik as the potential combat management system provider and integrator.
The underwater sensor suite will consist of Kongsberg's SS2030 active hull-mounted sonar and SD9500 lightweight over-the-side dipping sonar. In addition, Pohjanmaa-class corvettes will be equipped with Patria's lightweight dual-tow Sonac DTS that includes both an active variable-depth sonar as well as a passive towed receiving array.
Armament
Pohjanmaa-class corvettes will be armed with a single dual-purpose naval gun, surface-to-surface and surface-to-air missiles, anti-submarine torpedoes, naval mines, close-in weapon systems, and a decoy system.
The forward-mounted Bofors 57 mm Mk3 dual-purpose main gun will be recycled from the s. In addition, each Pohjanmaa-class corvette will be fitted with two Saab Trackfire remote controlled weapon stations for close-in self-defence and four Rheinmetall Multi Ammunition Softkill System (MASS) decoy launchers.
The primary surface-to-surface armament of the Pohjanmaa class is the Gabriel 5 subsonic anti-ship missile. The latest version of Israel Aerospace Industries's anti-ship missile family was selected over Kongsberg's Naval Strike Missile, MBDA's Exocet, Boeing's Harpoon and Saab's RBS15. In Finnish Navy service, the missile system will be referred to as PTO2020 (Pintatorjuntaohjus 2020, "surface defence missile").
Against aerial targets, Pohjanmaa-class corvettes will be armed with Raytheon RIM-162 Evolved Seasparrow Missile (ESSM) Block 2 surface-to-air missiles. Each vessel will be capable of carrying a total of 32 missiles quad-packed to eight Mark 41 Vertical Launching System silos. In Finnish Navy service, the system will be referred to as ITO20 (Ilmatorjuntaohjus 20).
For underwater warfare, the vessels will be fitted with Saab Torped 47 lightweight anti-submarine torpedoes. In addition, Pohjanmaa-class corvettes will be able to lay naval mines.