HSwMS Visby (K31)

History

Frigates date back to the "age of sails" where their speed, agility and modest firepower were put to good use. During this period, the type was built larger than the "Sloop-of-War" but smaller than the existing frigate models.

Frigates have entered the modern age of steel battleships and are now larger in size than coastal patrol boats and possibly smaller than frigates - the line between the two types of ships has become increasingly blurred with each passing decade.

The Swedish Navy has received a five-strong Visby-class frigate led by HSwMS Visby (K31). The class was originally designed to support six such ships, although the final form - HSwMS Uddevalla - was scrapped. This leaves the classes of HSwMS Visby (K31), HSwMS Helsingborg (K32), HSwMS Hamosand (K33), HSwMS Nykoping (K34) and HSwMS Karlstad (K35). HSwMS Visby was laid on 17 February 1995 and launched on 8 June 2000.

The ship continued to serve in the 4th Naval Battle Fleet (2013). She was built at the Kockums AB shipyard in Malmo, Sweden a German-owned company that is part of ThyssenKrupp Marine Systems Products.

Visby-class ships share many characteristics, including weapons, propulsion, and stealth. The armament centers on 1 x 57mm Bofors Mk 3 deck gun and 8 x RBS15 Mk 2 series anti-ship missiles (AShM). Introduced in 1995, the Bofors Mk 3 originated from the excellent Mk 1 series that debuted in 1964. Manufactured by Saab Bofors Dynamics, the RBS15 missile is a "fire-and-forget" anti-ship (AS) missile with land and attack capabilities - giving the missile a "dual role" presence on the battlefield.

The weapons are controlled by Ceros 200 Fire Control Radar System (FCRS), Condor CS-3701 Tactical Radar Surveillance System (TRSS) and Ericsson Sea Giraffe ABM 3D Processing Suite. The Combat Information Center (CIC) is located below the midship superstructure. Additional sensors are provided by the hull-mounted sonar array, the towed sonar array (stern) and the Variable Depth Sonar System (VDS) (stern) to counter threats from enemy submarines. Crews can also take advantage of a comprehensive countermeasures package that includes the Rheinmetallwaffe MASS (Multiple Ammunition Soft Kill System) decoy system. The ECM (Electronic Countermeasures) chaff launcher is located aft of the deck gun, and the radar warning system is mounted on the mast via a radome assembly.

The Visby class can also drop mines and depth charges if needed, and is equipped with torpedoes at the stern (4 x 40mm launchers, Type 45 torpedoes), making her a true all-rounder. Visby can also launch and recover Remotely Operated Vehicles (ROVs) for mine clearance and mine neutralization operations.

The Visby class at one point supported 8 x Umkhonto surface-to-air missile (SAM) launchers and 2 x 6 127mm ALECTO anti-submarine missile launchers, although these have since been phased out.

Propulsion at this level is managed by a CODAG (Combined Diesel and Gas) unit, where diesel and natural gas systems are integrated to provide maximum power propulsion through the integrated management of diesel and gas turbine units. CODAG allows surface combatants to achieve maximum straight-line speeds well in excess of the advertised cruising speed through a combined engine configuration controlled by a multi-speed gearbox (or multi-speed gearboxes).

Diesel engines typically feed oil to a gearbox, which is also fed by a gas turbine, which then drives the propeller directly. Depending on the vessel and operating conditions, this arrangement can increase speed by up to 10 knots.

The Visby is completed by 2 slow-running MTU Friedrichschafen 16V 2000 N90 diesel engines, each with an output of 1,300kW, housed in soundproof enclosures. They are connected to the required reduction gears, which are also connected to 4 Honeywell TF50A gas turbines, 4,000kW each. Three generators provide an additional 270 kW each. The top speed for this configuration is about 40 knots. The exhaust ports are heavily hidden at the rear.

2 KaMeWa 125 water jet propulsion "buckets" at the rear for precise handling. With a range of approximately 2,500 nautical miles and a cruising speed of 15 knots, it provides a stable range and operating radius for the Visby class. The vehicle navigation radar is retractable.

Like many other modern warships, Visby made extensive use of sloping concealment services in her hull design. This "stealth" approach on the high seas eliminates the use of gaps and vertical surfaces that have been very common in shipbuilding for decades. The end result is a clean and well-defined design designed to reduce radar signatures from curious enemy systems. While it doesn't actually make the ship invisible, the ship still maintains an imperceptible presence. Additionally, deck guns can be stowed in the forward box to further reduce side profile features.

The bridge is perched high on a pyramid-shaped superstructure, and it's impressive to see what's going on around the ship. All smoke funnels are intentionally short and enclosed within the structure. The radar field (commander) is located in front of the bridge and behind the deck guns.

The mast is also completely enclosed, and the track section exists only around the rear of the boat, including the superstructure and aft deck. There is a helipad on the stern deck for up to one medium helicopter. All helicopter-related gear can be disassembled to maintain camouflage.

The helicopter's "bunker station" was attached to the rear of the superstructure. RHIBs (Rigid Hull Inflatable Boats) are also portable and can be launched and retrieved as needed.

HSwMS Visby normally has a crew of 43, including 27 officers and 16 conscripts. She displaces 650 tons, has a barrel length of 72.6 meters, a beam (width) of 10.4 meters and a draft of 2.5 meters - the latter qualities that allow the vessel to operate at sea. The vessel is designed for near-shore (coastal) and deep-sea operations, allowing her to participate in international efforts as they arise. Although her armament is limited compared to modern guided missile frigates, she is still practical and ensures the ship remains agile and fast in open water.

Additionally, the type's improved endurance allows the ship to stay longer (and disembark quickly if necessary) than other smaller classes. In this way, Visby can be used for all types of missions, including maritime rescue (downed pilots, humanitarian, etc.), anti-piracy services, customs supervision, maritime law enforcement, interception of large and small ships and as a rapid attack platform.

The Visby-class can also operate independently or as part of the main naval forces sponsored by Sweden and the United Nations.

Specification

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