Visby-class corvette

The hull is constructed with a sandwich design consisting of a PVC core with a carbon fibre and vinyl laminate[4] (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.[5]

Visby's angular tumblehome design reduces its radar signature. 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."[1] 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.

Much of the design was based on the experiences learned from the experimental ship HSwMS Smyge. The class was originally designed to be divided into two subcategories where the last ship was optimized for surface combat and 4 others for submarine hunting; however, this was changed due to cutbacks.

A helicopter, such as the Agusta Westland A109M selected by Sweden, can land, take off, and refuel on the upper deck. A helicopter hangar was originally planned but was considered to be too cramped and was removed.

The ships took an exceptionally long time from launch to delivery and the construction has been fraught with repeated delays. In 2008, the only weapons system that had been integrated and tested in Visby was the gun.

Finally, on 16 December 2009, the first two of the corvettes were delivered to the Swedish Navy by the Försvarets materielverk (FMV).[6] The two ships, K32 and K33, were delivered with underwater and surface/air sensors fully integrated. However, the only weapon that had been integrated and test-fired on the ships was still the Bofors 57 Mk3 gun. The FMV calls this version 4, which aims to get the ships into service and start training crews.

HSwMS Visby

Version 5 is due in 2012 and is intended to supplement the ships with mine clearance systems, helicopter landing capability (only K31 is certified to date), anti-surface ship missiles, and additional stealth adaptation. Visby was the first of the corvettes to be upgraded to Version 5. On 22 March 2012 FMV reported that the ship had been modified and that the system would be tested before reentering the Swedish Navy by the end of 2012.[7]

Although the design of the ships originally called for the installation of surface-to-air missiles, on 18 September 2008 the Genomförandegruppen cancelled the project in order to rationalize the procurement of defence materiel for the Swedish defence.[8]

Number	Ship name	Laid down	Launched	Commissioned	Service	Status	Coat of arms
K31	Visby	17 February 1995	8 June 2000	16 September 2002	4th Naval Warfare Flotilla	Active
K32	Helsingborg		27 June 2003	16 December 2009	4th Naval Warfare Flotilla	Active
K33	Härnösand		16 December 2004	16 December 2009	3rd Naval Warfare Flotilla	Active
K34	Nyköping		18 August 2005	16 September 2015	3rd Naval Warfare Flotilla	Active
K35	Karlstad		24 August 2006	16 September 2015	3rd Naval Warfare Flotilla	Active
K36	Uddevalla	Cancelled

All systems for the ship Uddevalla were acquired, but the ship was later canceled, so there are now plans to build a full Visby class simulator.

PTK Visby is the designation of the formation doing system tests and readying the ships for active service within the Swedish Navy. The formation is under the 3rd Naval Warfare Flotilla but takes its orders from the FMV. The system tests are taking a long time partly because of funding issues and partly because of the novel and cutting-edge nature of the platform.

• Tuo Chiang stealth corvette (Taiwan)
• Baynunah-class corvette (United Arab Emirates)
• Hamina-class missile boat (Finland)
• Type 022 missile boat (China)
• Milgem-class corvette (Turkey)
• Skjold-class corvette (Norway)

• 
  HSwMS Helsingborg on a visit to the city Helsingborg.
• 
  Anchored off Gotska Sandön.
• 
  At Karlskrona Naval Base.
• 
  In Stockholm City.

Wikimedia Commons has media related to Visby-class corvette.

• Official builder's homepage (as of 2018)
• Swedish navy page on the Visby trials (in Swedish)
• Naval-Technology - www.naval-technology.com