The Kobben-class diesel-electric-powered attack submarine was developed by West Germany for the export market. The design eventually found a home with the Royal Norwegian Navy who used it as their primary submarine for some time. Fifteen were eventually commissioned and built from 1963 to 1966. They began service in 1964 and four were ultimately sold off to the Royal Danish Navy and another four to the Polish Navy, the latter of which continues operation of at least two of these boats (as of January 2019). The remaining units have all been either scrapped or preserved as museum ships.
The Kobben-class was forged out of the work used to bring about the Type 201 for the West German Navy, the first submarine class to emerge from Germany in the post-World War 2 world. Like the Type 201 boats, the Kobben-class was designed specifically to operate the shallower waters off the coast and, as such, they were dimensionally smaller and held modest crew sizes compared to deep-water contemporaries found in the West during the period. Larger than the Type 205 boats that succeeded the Type 201, the Kobben-class could be used to target enemy merchant shipping and deter enemy forces from water sources in and around Norwegian waters.
The general failing of the Type 201 boats was there non-magnetic hulls which were devised to protect them from naval mines. Fracturing was a constant source of worry for these boats which led to the Type 205s being hastily drawn up as a response.
Nevertheless, the West German Navy's U-3 example was loaned to the Royal Norwegian Navy from the period spanning 1962 to 1964 and operated as the "Kobben" - subsequently returned to continue its career as U-3 in West German service. Norway completed its evaluation of the new submarine and selected it for its coastal patrol needs as few submarine designs of the time offered the same capabilities sought by the Royal Norwegian Navy. The Germans then constructed new submarines based on the Norwegian requirement under the "Type 207" classification and, to the Norwegians, these became the "Kobben-class". All of the class were built by Rheinstahl Nordseewerke GmbH of Emden.
The first vessels to be commissioned were Kinn, Kya, Kobben, and Kunna in April, June, August, and October, respectively. The next batch arrived in 1965 (Kaura, Ula, Utsira, Utstein, Utvaer, and Uthaug) followed by three more in 1966 (Skinna, Skolpen, and Stadt) and the final two in 1967 (Stord and Svenner).
As built, the class featured a propulsion scheme made up of 2 x MTU diesel engines of 1,100 horsepower and 1 x Electric motor of 1,700 horsepower driving a single shaft astern. Speeds could reach 10 knots while surfaced and 17 knots while submerged. Range was out to 4,200 nautical miles. Aboard was a crew of twenty-four and armament was just eight torpedoes fired from 8 x 533mm (21") tubes. Dimensions of the boat includes a running length of 155 feet, a beam of 15 feet, and a draught down to 12 feet. Surfaced displacement reached 500 tons (short) while submerged displacement peaked at 535 tons.
In 1985, a program was drawn up to modernize and lengthen six of the class, the latter by nearly seven feet, to accommodate new equipment including an all-new sonar fit. This work lasted until 1993 and extended the useful service lives of this lot for the foreseeable future. About the same time, which by this time witnessed the collapse of the Soviet Empire, four of the class were sold off to neighboring Denmark: one became a platform for spares (Kaura) while Kya, Utvaer, and Uthaug became HDMS Springeren, HDMS Tumieren, and HDMS Saelen, respectively.
A further five boats of the Norwegian stock were refurbished and sold off to the Polish Navy where they were operated as ORP Kondor, ORP Sep, ORP Sokol, and ORP Bielik (ex-Kunna, ex-Skolpen, ex-Stord, and ex-Svenner, respective). Another (Kobben) was taken on as a spares unit.
Norway eventually succeeded the Kobben line with the Ula-class of which six were procured and all six remain in active service today (2019). The last Kobben-class boat in Norwegian service was relieved of duty in 2001 and the Royal Danish Navy followed with the class's retirement in 2004. Two Polish boats remain in active service today (2019) and two Koppen-class boats have been preserved as museum ships (Ulstein and HDMS Saelen). The rest were scrapped.