en HSwMS Sj%C3%B6bj%C3%B6rnen (Sbj)

	HSwMS Sjöbjörnen underway between 1970-1989.
History
Sweden
Name	Sjöbjörnen
Namesake	Sjöbjörnen
Ordered	1966
Builder	Karlskrona naval base
Launched	9 January 1968
Commissioned	28 February 1969
Decommissioned	1997
Motto	Nulli secundus ; (Second to none);
Nickname(s)	Sbj
Fate	Sold to Singapore in 1997
Singapore
Name	Challenger
Namesake	Challenger
Acquired	28 May 1999
Commissioned	2000s
Decommissioned	11 March 2015
Homeport	Changi
Fate	Scrapped
General characteristics
Class and type	Sjöormen-class submarine; Challenger-class submarine;
Displacement	1,130 t (1,112 long tons) surfaced; 1,210 t (1,191 long tons) submerged;
Length	50.5 m (165 ft 8 in)
Beam	6.1 m (20 ft 0 in)
Draught	5.8 m (19 ft 0 in)
Propulsion	2 × Hedemora diesel generators; 1 × electric motor; 1 shaft;
Speed	20 knots (37 km/h; 23 mph)
Complement	25 officers and enlisted
Armament	4 × 533 mm (21 in) torpedo tubes; 2 × 400 mm (16 in) torpedo tubes;

HSwMS Sjöbjörnen (Sbj), Sw. meaning sea bear, was the third ship of the Swedish submarine class Sjöormen, project name A11.^[1]

Development

The planning of the class included a number of different AIP solutions including nuclear propulsion. However, the ships where finally completed with for the time extremely large batteries. The ship was a single-hulled submarine, with the hull shape influenced by the American experimental submarine USS Albacore. The hull was covered with rubber tiles to reduce the acoustic signature (anechoic tiles), at this time a pioneering technology. The Sjöormen class also pioneered the use of an x-shaped (as opposed to cross-shaped) rudder as a standard (as opposed to experimental) feature.^[2]

Service in Sweden

The submarine served in the Swedish Navy for almost 30 years and was then sold to Singapore in 1997 together with its four sister ships.

Service in Singapore

HSwMS Sjöbjörnen was renamed RSS Challenger after Singapore acquired the boat on 28 May 1999. She was commissioned on 26 June 2004 after a major refit. After 11 years in the Republic of Singapore Navy, she was decommissioned on 11 March 2015 and scrapped.^[3]