Ula class

    Since the deletion of the last six of the original 15 Kobben-class boats in the second half of the 1990s, the Norwegian navy operates just six submarines in the form of the boats of the Ula class with diesel-electric propulsion. The boats are named Ula, Uredd, Utvaer, Uthaug, Utstein and Utsira, all but the second of these names having been used for the boats of an earlier Ula class (five British U-class submarines bought from the UK in 1943-46, modernized in 1955-56 and deleted in the first part of the 1960s).

   The current Ula-class submarines are intended primarily for coastal operations, and are therefore comparatively small in size and limited in their diving depth to some 250 m (820 ft).

   The entire class was ordered from Thyssen Nordseewerke of Emden on 30 September 1982 in a joint Norwegian and West German programme known in the latter country as Project 210, but the option for another two boats of the class was not, in the event, exercised.

   Although the boats were completed in the West German yard they did incorporate a measure of Norwegian structural expertise inasmuch as sections of the pressure hulls were fabricated in a Norwegian facility and then shipped to Emden for inclusion into the otherwise German-built boats. The boats were laid down between January 1987 and June 1990, launched between July 1988 and November 1991, and finally commissioned into Norwegian service in the period between April 1989 and April 1992.

   Though much of the hull and all of the propulsion machinery are German, the boats were completed with a mix of French, German and Norwegian systems. The basic command and weapon control systems are Norwegian (the torpedo fire-control system being the Kongsberg MSI-90U that is being upgraded and modernised in 2000-05), while the sonars are of French and German origins. The Thomson-CSF low-frequency passive flank-array sonar is of French origin, and is based on piezoelectric polymer technology offering significantly reduced flow noise. The Atlas Elektronik CSU 83 medium-frequency active/passive intercept, search and attack sonar, however, is on German origin. Another notable feature, designed to reduce the need to incorporate apertures in the pressure hull, is the use of Calzoni Trident modular non-penetrating masts, and the periscopes use Zeiss optics.

   Since entering service, the Ula-class submarines have been found to suffer from noise problems with their machinery, which is a major handicap in submarine operations in which sound is the primary medium for discovering submerged boats. The submarines have undergone quite interesting careers to date. The Ula, for example was damaged by a practice torpedo during the boat's trials in 1989, while the Uredd in March 19991 was damaged in a docking accident and then in February 1992 suffered a control room fire.