According to information published by Thai PBS World on February 7, 2022, China has offered two used Song-class submarines free of charge to the Royal Thai Navy (RTN), but they need to be reconditioned before they can become operable.
The Type 039 submarine (Song-class) is a class of diesel-electric submarines of the People’s Liberation Army Navy. The class is the first diesel-electric submarine to be fully developed within China and also the first Chinese diesel-electric submarine to use the modern teardrop hull shape.
The submarine uses a modern teardrop-shaped hull for underwater performance. The hull incorporates four rudders and is propelled by a single propeller.
The primary weapon for the Type 039 is the 533 mm Yu-4 torpedo, a locally produced passive homing 40-knot (74 km/h) torpedo based on the SAET-50 and roughly comparable to the SAET-60. Surface targets may be attacked at up to 15 km.