Oslo-class frigate

HNoMS Narvik during a port visit in Trondheim in 2006
Class overview
Name:	Oslo class
Builders:	Navy Main Yard, Karljohansvern, Horten, Norway
Operators:	Royal Norwegian Navy
Succeeded by:	Fridtjof Nansen-class frigate
Built:	1964–1966
In commission:	1966–2007
Completed:	5
Lost:	1
Retired:	3
Preserved:	1
General characteristics
Type:	Frigate
Displacement:	1,735 long tons (1,763 t) standard 2,100 long tons (2,134 t) full load
Length:	96.6 m (316 ft 11 in)
Beam:	11.2 m (36 ft 9 in)
Draft:	5.5 m (18 ft 1 in)
Propulsion:	Twin steam boilers, one high pressure and one low pressure steam turbine, 20,000 hp (14,914 kW)
Speed:	25 knots (29 mph; 46 km/h)
Range:	3,900 nmi (7,200 km) at 15 kn (17 mph; 28 km/h)
Complement:	120 (129 max) officers and men
Sensors and processing systems:	Siemens/Plessey AWS-9 long range air search radar Racal DeccaTM 1226 surface search radar in I band Kongsberg MSI-90(U) tracking and fire control system Raytheon Mk 95; I/J-band search and track radar for Sea Sparrow Medium frequency Thomson-CSF Sintra/Simrad TSM 2633 combined hull and VDS active sonar High frequency Terne III active sonar
Electronic warfare & decoys:	4 × Mark 36 SRBOC chaff launchers ESM: AR 700 suite
Armament:	2 × 3 in (76 mm) cannon 1 × Bofors 40mm/70 anti-aircraft gun 2 × 20 mm Rheinmetall anti-aircraft guns 2 × 12.7 mm anti-aircraft guns 6 × Penguin SSMs (usually not mounted) 1 × 8-cell Raytheon RIM-7M Sea Sparrow Mk 29 SAM system 6 × Kongsberg Terne ASW rocket-thrown depth charges 2 × triple 324 mm (12.8 in) Mark 32 torpedo tubes (Sting Ray torpedoes)

The Oslo-class frigate is a Royal Norwegian Navy frigate design, based on the US Navy Dealey-class destroyer escorts. The forward hull was customized to suit Norwegian sea conditions better (higher freeboard) and several sub-systems were European built.

All ships were built at the Navy Main Yard in Horten, Norway between 1964 and 1966. The construction of the vessels was part of the Navy rebuilding program, approved by the Norwegian government in 1960. Half of the project expenses were funded by the United States as a part of the Mutual Defense Assistance Program (MDAP) (a program that ran from when it was passed by the Congress in October 1949 until 1967–68).

In the late 1970s, the class received new armament, most notably Penguin, RIM-7 Sea Sparrow and Mark 32 torpedo launchers. Another modernization was carried out in the 1980s.

During 1995 and 1996, after HNoMS Oslo experienced an engine failure, and subsequently sank after sailing in heavy weather, the rest of the class was once again modernized. The hulls were strengthened, which in turn increased the displacement with 200 tonnes.

All of the Oslo class are now retired, with HNoMS Narvik preserved as a museum ship. The Oslo class were replaced by the Fridtjof Nansen-class frigates. This replacement started in mid-2006.

Five frigates of this class were built. All of them were modernized during the period 1987–1990. They bear the prefix KNM (Kongelig Norske Marine, meaning Royal Norwegian Navy) in Norwegian and HNoMS (His Norwegian Majesty's Ship) in English.

The lead ship, Oslo, ran aground near Marstein island on January 24, 1994. One officer was killed in the accident. The next day, on January 25, she was taken under tow. She sank on the same day in Korsfjorden outside Steinneset in Austevoll county.