The Visby-class stealth missile corvettes serve the modern Swedish Navy in a prominent roles. Six were originally planned for the group, which utilizes an advanced design for enhanced "stealthiness", but only five were eventually realized: HSwMS Visby (K31), Helsingborg (K32), Harnosand (K33), Nykpoing (K34), and - the focus of this article - Karlstad (K35). Budget limitations led to Uddevalia (K36) being cancelled. Similarly, an original "twin-group" operating approach for the class, in which one half was to fulfill an anti-submarine role and the other a surface combatant role, was simplified due to cost.
All of the ships can trace their lineage back to the earlier HSwMS Smyge stealth-centric technology demonstrator.
Corvette warships are the dimensionally smallest available warship to all navies. In today's modern setting, such ship types are typically used in the fast-attack or coastal patrol roles and are designed to meet emerging threats head-on through speed and a modest display of firepower. The Visby-class does this one better in being designed around a stealth approach to reduce its signature and profile to enemy vessels - substantially reducing the corvette's detection range by enemy systems.
Karlstad (K35) follows the Visby-class design standard with heavy implementation of angled, slab sides to achieve a "stealthy" result. These ships are not wholly invisible to radar but every attempt is made to foil their detection by modern search-and-tracking systems the enemy might use. The design approach therefore makes a continuous, unbroken hull line from bow to stern, joining the upper and lower sections of the hull superstructure to appear as a single component. The hull superstructure is well-contoured into the hull as a result and houses the bridge section, sub-decks and a low-profile, wholly-enclosed mast at its top. The turreted deck gun is positioned at the forecastle in the usual way and also utilizes angled faces while having an inherent feature to partially "tuck" down into the hull during travel (preserving the ship's stealthy qualities). Over the stern is a single-helicopter pad supporting a medium-lift type or similar rotary-wing system. Plans for implementing a full-service hangar facility was scrapped for the class with space concerns being cited. Structural dimensions include a running length of 239 feet, a beam of 34 feet, and a draught of 7.9 feet. Aboard is a complement of 40 to 43 personnel.
Karlstad is powered by 4 x Vericor TF50A gas turbines coupled with 2 x MTU Friedrichshafen 16V2000 N90 marine diesels. This is arranged in a COmbined Diesel-Or-Gas (CODOG) configuration allowing the ship to use one propulsion set over the other for better fuel management to accomplish distinct actions (general cruising, dashing). This is supported by 3 x 270kW generators as well as 2 x 125SII Kamewa waterjets. All told, the ship can make headway at up to 35 knots in ideal conditions and sports an operational range out to 2,500 nautical miles.
Like its sisters, Karlstad is outfitted with both projectile- and missile-based weapons to counter various at-sea threats. 1 x 57mm Bofors Mk.3 Dual-Purpose (DP) automatic gun is set with a turreted positioned over the forecastle and there are 8 x RBS16 Mk.2 Anti-Ship Missile (ASM) launchers for countering at-range surface threats. 4 x 400mm torpedo tubes (supporting the Type 45 torpedo family) can be brought to bear on both on-sea and undersea targets as needed. The vessel is further equipped to disperse naval mines and depth charges which are crucial capabilities in a war time setting.
The vessel is outfitted with a GDC hull-mounted sonar and GDC variable depth sonar system. The Condor CS-3701 makes up the tactical radar surveillance system while Saab provides the Ceres 200 series stealth fire control radar unit. Saab also supplies the 9LV combat management system aboard as well as the "Sea Giraffe" AMB 3D PESA surveillance radar unit. Self-preservation is made possible by the Rheinmetall TKWA/MASS (Multi-Ammunition, "Softkill" System). The original ship design was also intended to feature Surface-to-Air Missiles (SAMs) and Anti-Submarine ROCket (ASROC) launchers but these features were eventually dropped due to cost.
Karlstad was launched on August 24th, 2006, commissioned on September 16th, 2015, and currently serves the 3rd Naval Warfare Flotilla with an active status. The class fought through a lengthy delay period resulting in equally-delayed commissioning dates - the first was in 2002 with the last being 2015.