The Alta class was built by Kværner Mandal during 1996 and 1997, while the related Oksøy class was built in 1994 and 1995. A total of 9 vessels were built, 5 minesweepers and 4 minehunters. The catamaran hull is built in a fibre-reinforced plastic sandwich of very low magnetic signature.[1]
Two large fans located on each side create an air cushion between the two hulls and a front and aft rubber skirt, lifting the vessel, giving small drag and a high cruise speed, as well as low susceptibility to the shock of exploding mines since only a small portion of the hull is actually exposed in the water. Propulsion by water jet, again one in each hull, gives a low acoustic signature. A degaussing system gives the vessels extremely low electromagnetic signature.
| Alta class[2] | |||||
| Number | Name | Builder | Commissioned | Status | |
|---|---|---|---|---|---|
| M350 | Alta | Kværner, Mandal | 12 January 1996 | Scrapped some time prior to 23 July 2022[3] | |
| M351 | Otra | 8 November 1996 | |||
| M352 | Rauma | 2 December 1996 | |||
| M353 | Orkla | Destroyed by fire on 19 November 2002[4] | |||
| M354 | Glomma | 1 July 1997 | Sold 2009[5] |
Orkla was destroyed by fire on 19 November 2002.[4] Glomma is no longer in active service. Alta was scrapped along with the Oksøy class M341 Karmøy prior to 23 July 2022