Visby - class corvette The Visby is the latest class of corvette to be adopted by the Swedish Navy after the " Göteborg " and the " Stockholm " class corvettes . The ship ' s design heavily emphasizes low visibility or stealth technology . 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 . Design . 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 . The " 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 . " Even 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 . History . 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 some ships were optimized for surface combat and others for submarine hunting ; however , this was changed due to cutbacks . A helicopter , such as the AgustaWestland 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 December 16 , 2009 , the first two of the corvettes were delivered to the Swedish Navy by the FMV . 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 . 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 adaption . HMS " Visby " was the first of the corvettes to be upgraded to Version 5 . On 22 March 2012 RMV reported that the ship had been modified and that the system would now be tested before reentering the Swedish Navy by the end of 2012 . Although the design of the ships originally called for the installation of surface - to - air missiles , in 2008 the decision was made not to install any , because of budget considerations . Units . 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 .