The Singapore Navy announced that it has ordered two Type 218SG submarines from a German firm. These will arrive by the end of the decade and few details were given out but the Type 218SG appears to be a variant of the Type 216 that the manufacturer proposed in 2012. Thus the Type 218 would displace more than 3,000 tons on the surface, have AIP and a lot of electronics built in Singapore. These boats would be highly automated and require a crew of less than 40 and have accommodations for a dozen or more additional personnel (commandos or trainees). AIP (underwater) endurance would be 25-30 days and total endurance would be 80 days. There would be six 533mm (21 inch) torpedo tubes and 18 torpedoes or anti-ship missiles. These boats will cost at least $600 million each and won’t arrive until 2020.
Singapore already has a submarine force. In 2011 Singapore received the first of two refurbished Vaastergotland class submarines from Sweden with the second one arriving in 2012. The refurb was really a rebuilding of these boats, as their size was increased by a third. The rebuilt boats were renamed the Archer class. The 1,400 ton Archers are 60.5 meters (198.5 feet) long, carry a crew of 28 and are armed with six 533mm and three 400mm (15.75 inch) torpedo tubes. The 400mm torpedo is for other subs, while the larger torpedo is for surface ships. These tubes can also carry mines.
The two Swedish subs were sold to Singapore in 2005, and spent six years being rebuilt and upgraded. For example, the boats now have air conditioning and other mods useful for subs spending all their time in tropical waters. In addition to new electronic systems, the boats have air-independent propulsion (AIP), which accounts for most of the added size. Surface speed is 15 kilometers an hour, while submerged speed is 28 kilometers an hour.
Sweden built the four Vaastergotland class boats in the 1980s, and these were succeeded by the Gotland class in the 1990s. Gotland was the first submarine designed from the start to use AIP. The Gotland can remain submerged for 19 days and is among the quietest non-nuclear submarines in the world. The four Gotland class boats are highly automated, with a crew of 25. They displace 1,494 tons, are 61.3 meters (190 feet) long and have four 533mm torpedo tubes (with 12 torpedoes) and two 400mm tubes (with six torpedoes). The refurbished Vaastergotlands come very close to matching the Gotlands in performance. The two Vaastergotland class subs that remained in Swedish service received a similar upgrade, before Singapore bought the two other Vaastergotland boats.
The two Archers and the two Type 218SGs will replace the four Challenger class subs. In 1995, Singapore purchased four Swedish Challenger Class (ex-Sjöbjörnen Class), the first of which was launched in 1968. The Challenger Class were not only refitted for tropical conditions, but also received weapons system and sensor upgrades. These submarines performed very well in exercises against US Navy and Royal Australian Navy units, proving that these old boats, when handled well in littoral conditions, are quiet and maneuverable subs that are able to give a pretty good account of themselves.