Visby-class corvette

HSwMS Helsingborg (K32)
Class overview
Name:	Visby class
Builders:	Kockums
Operators:	Swedish Navy
Preceded by:	Göteborg class
Cost:	$184 Million
In commission:	16 December 2009
Planned:	6
Completed:	5
Cancelled:	1
Active:	HSwMS Visby HSwMS Helsingborg HSwMS Härnösand HSwMS Nyköping HSwMS Karlstad
General characteristics
Type:	Stealth Missile Corvette
Displacement:	640 tonnes
Length:	72.7 m (239 ft)
Beam:	10.4 m (34 ft)
Draught:	2.4 m (7.9 ft)
Propulsion:	CODOG 2 × 125SII Kamewa Waterjets 4 × Vericor TF50A gas turbines, total rating 16 MW 2 × MTU Friedrichshafen 16 V 2000 N90 diesel engines, total rating 2.6 MW 3 × generators of 270kW each
Speed:	35 knots (65 km/h)+
Range:	2,500 nmi (4,600 km) at 15 kn (28 km/h)
Complement:	43
Sensors and processing systems:	Saab 9LV combat management system Saab Sea_GIRAFFE AMB 3D PESA surveillance radar Saab Ceros 200 stealth fire control radar system Condor CS-3701 tactical radar surveillance system GDC Hull-mounted sonar Hydroscience Technologies towed array sonar system GDC variable depth sonar
Electronic warfare & decoys:	Rheinmetall TKWA/MASS (Multi Ammunition Softkill System)
Armament:	1 × Bofors 57 mm Mk3 4 × RBS15 Mk2 anti-ship missiles 4 × 400 mm torpedo launchers for Type 45 torpedoes Mines and depth charges Provision for but not fitted with 2 × 6 127 mm ALECTO anti-submarine rocket launchers (cancelled) 12 × Umkhonto SAM (cancelled)
Aviation facilities:	Helicopter pad

The Visby class is the latest class of corvette to be adopted by the Swedish Navy after the Göteborg and corvettes. The ship's design heavily emphasizes low visibility, radar cross-section and infrared signature. The first ship in the class is named after Visby, the main city on the island of Gotland. The class has received widespread international attention because of its capabilities as a stealth ship.

The ships are designed by Swedish Defence Materiel Administration (FMV) and built by Kockums AB. The first ship of the class was launched in 2000 and since then the construction was fraught with repeated delays. Finally in December 2009, the first two ships of the class were delivered to the Swedish Navy by the FMV, albeit with greatly reduced operational capability.

The hull is constructed with a sandwich design consisting of a PVC core with a carbon fibre and vinyl laminate (see also the Oceanic-Creations spin-off). There are multiple advantages to using composite materials in ship hulls. Good conductivity and surface flatness means a low radar signature, while good heat insulation lowers the infrared signature and increases survivability in case of fire. The composite sandwich used is also non-magnetic, which lowers the magnetic signature. Composites are also very strong for their relative weight, and less weight means a higher top speed and better maneuverability. The composite weighs roughly 50% less than the equivalent strength steel. If built with normal steel the ship would weigh in at around 1200 tonnes.

Visby's angular design reduces its radar signature (or radar cross section). Jan Nilsson, one of the designers, told BBC News Online: "We are able to reduce the radar cross section by 99%. That doesn't mean it's 99% invisible, it means that we have reduced its detection range." The 57 mm cannon barrel can be folded into the turret to reduce its cross section. There are plans for additional improvements in this area, especially for the deck rails and masts.

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Wikipedia