The RSS Archer will undergo sea trials between now and its arrival in Singapore late next year.

Balloons and cheers filled the air yesterday as Mrs Teo Poh Yim, the wife of Deputy Prime Minister Teo Chee Hean, smashed a bottle of champagne against the vessel's sleek black hull, in keeping with maritime tradition.

The eventual delivery of the 60.5m diesel-electric vessel and the RSS Swordsman will allow the Republic of Singapore Navy (RSN) to retire some of its Challenger-class boats which are more than 30 years old.

The RSS Archer, built by Swedish company Kockums in 1987, underwent upgrading and refurbishment to prepare it for the warmer, more corrosive waters around Singapore.

It has been fitted with a state-of- the-art Air Independent Propulsion system which allows it to last six weeks at sea - twice as long as the older Challenger-class submarines.

The older submarines have to surface periodically to recharge their batteries, making them vulnerable to detection. The RSS Archer's ability to stay submerged longer makes it stealthier. It is also armed with more torpedoes.

DPM Teo, who is the Defence Minister, said the submarines are among the set pieces in the RSN arsenal, operating in concert with the six stealth frigates and the soon-to-be-delivered naval helicopters.

All this hardware will enable the navy to undertake 'more sophisticated operations to help maintain regional peace and stability and secure the vital sea routes through our region', he added.

Mr Teo credited the Royal Swedish Navy, which has operated submarines for more than a century, for helping Singapore strengthen its fleet quickly.

Read the full story in Wednesday's edition of The Straits Times.