Singapore’s third Invincible-class (Type-218SG) submarine arrives home

The Republic of Singapore Navy (RSN) has announced the arrival of the third Invincible-class (Type 218SG) submarine, RSS Illustrious, which sailed into Changi Naval Base on 10 April 2026, likley after it was delivered by the heavy transport ship, MV Rolldock Star, which is now anchored off Singapore. 

Image: MINDEF Singapore. RSS Illustrious docks at Changi Naval Base

Singapore ceremonially launched the second and third boats of the class in December 2022, but while RSS Impeccable was delivered to Singapore and fully commissioned in September 2024 (alongside RSS Invincible), RSS Illustrious still required dockside fitting out and builder's trials until late 2025. 

The fourth boat of the class, RSS Inimitable, was launched in April 2024, and is now completing its builder's trials in Kiel Germany, and will make its own journey to Singapore before 2028.

The Invincible-class are the most modern submarines in South East Asia, and will remain so until Thailand takes delivery of its much delayed S26T in late 2028.

Indonesia has two Scorpene Evo on order, and national shipbuilder PT PAL will commence production in June 2026.

When will the Archer-class retire?

Image: Singapore Navy.

I originally expected the RSN to retire both Archer-class submarines with the delivery of the third and fourth Invincible-class, to keep Singapore’s operational submarine force at four advanced AIP boats, but with the follow-on order for two more Type-218SG, confirmed in May 2025 has now torpedoed my expectations, as it is very clear that the RSN has settled on a future submarine fleet size is of six boats.

While the Archer boats were originally built in the mid-1980s as the first two Vastergotland-class SSKs, both were decommissioned in 1997 after a decade of service. Sold to Singapore in 2005, they underwent an extensive refit and upgrade that included tropicalization, air conditioning and a Stirling AIP module, before commissioning into the RSN in 2011 and 2013. 

While RSS Archer’s hull was built 40 years old, the boat has “only” been in commission in the RSN for 15 years, or 25 years if you include its HSwMS service, so it is quite conceivable that the RSN still regard these two boats as capable and intend to keep them in service until the third batch of Invincible boats is delivered by TKMS before 2034.