Alta-class minesweeper

The Alta class minesweeper is a ship class of minesweepers operated by the Royal Norwegian Navy. An almost identical class of minehunters is known as the Oksøy class.

The Alta class was built by Kvaerner 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. HNoMS Orkla was completely destroyed in a fire, and HNoMS Oksøy was damaged when it ran aground in 2005. The pair, along with HNoMS Glomma, are no longer in active service. The catamaran hull is built in a fibre-reinforced plastic sandwich of very low magnetic signature.

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.