Visby Offers Radical Stealth Design

The Visby corvette can be regarded as a victory for the ”Swedish Model”, entailing the close cooperation of many expert institutions over a period of many years. In this case it involved Kockums collaborating with the Swedish Defence Material Administration and the Royal Institute of Technology. Together they have been responsible for the technical development, projection and construction, which has resulted in a flexible surface vessel with the best possible advantages for high and low speeds.

Six Visby-class corvettes are on order and production is fully underway at Kockums Shipyard in Karlskrona. The vessels now under construction will be the first and largest in the world and in which no concessions have been made in obtaining the best possible stealth characteristics. In depth-research and many tests formed the basis for the decision to build the Visby in carbon fibre.

The Visby-class corvettes are designed to give the lowest possible signature. The hull has large flat surfaces and sharp edges. Everything that is not required externally has been built in or concealed under hatches. To give the vessel a low IR signature the exhaust from the gas turbines is released at the rear of the vessel near the surface of the water. The magnetic signature is also extremely low for a vessel on this size. The hull is fully non-magnetic and the same will apply to all onboard equipment.

The hull, which is optimized for an extremely high level of seaworthiness, is also very easy to maneuver. It is specially designed for water jet propulsion. Early in the process it became clear that a very low hull weight at an acceptable cost was decisive for the vessel´s total performance and impact. To meet these requirements and at the same time obtain good stealth properties, the hull is constructed using a sandwich design consisting of a PVC core with carbon fibre/vinylester laminate. This gives a high level of strength and durability, low weight, good shock resistance, integrated low magnetic signature, all at a feasible cost. The hull is built of flat panels, manufactured with the vacuum injection method. The panels are then joined to four large sections: fore section, centre section, aft section and deckhouse.