Indo Defence 2025: PT PAL prepares to launch first autonomous submarine

A model of the KSOT on display at Indo Defence 2025 exhibition. (Janes/Ridzwan Rahmat)

Indonesian state-owned shipbuilder PT PAL has produced the first prototype of an indigenously developed autonomous submarine and is preparing to launch the vessel in the later part of 2025.

Speaking to Janes at the Indo Defence 2025 exhibition, PT PAL's general manager of the Design Division Chabibi Nur Tahlil confirmed that construction work on the submarine – which is known in-country as the Kapal Selam Otonom (KSOT) – began in January 2025.

It is similar to the KSOT concept that was unveiled at the 2022 iteration of Indo Defence, but has a shorter overall length of about 15 m instead of 25 m.

The vessel has a breadth of 2.2 m, a draught of 1.85 m, and a displacement of about 37 tonnes when submerged.

Powered by an electric motor, the KSOT has a maximum speed of 8 kt and a cruising speed of 5 kt. At the cruising speed, the vessel has an endurance of 18 hours with a maximum range of 90 n miles.

There are plans to increase the KSOT's endurance and maximum range to six months and 6,000 n miles, said Chabibi.

The KSOT that will be launched in 2025 is a generic prototype but PT PAL plans to eventually produce three different variants of the autonomous submarine.

These are namely a torpedo variant, a surveillance variant, and a suicide variant.

For the torpedo variant, the KSOT will be able to carry and deploy up to two heavyweight torpedoes per mission. Instructions to launch the torpedoes can be relayed remotely once the vessel has reached its intended position.