HTMS Naresuan

HTMS (His Thai Majesty's Ship) Naresuan (FFG 421), (Thai: นเรศวร) hull number 621, commissioned in 1995, is a modified version of the Chinese-made Type 053 frigate, corporate designed between Royal Thai Navy and China but built by the China State Shipbuilding Corporation in Shanghai. Her sister ship, HTMS Taksin was delivered in November 1995. The ships came at 2 billion baht each, much less than the 8 billion baht price tag for Western-built frigates.

When Thailand ordered four new 053 frigates in 1990, China built them to the (then) latest 053H2 (Jianghu III) standard. Two were modified with helicopter decks in the back. Although the price was excellent (2 billion baht each, compared to 8 billion baht for western ships), the Thai Navy complained of quality issues. The interior wiring was exposed and had to be re-wired. The ship's battle damage control system was very limited, with poor fire-suppression system and water-tight locks. It's said that if the ship's hull was breached, rapid flooding would lead to loss of ship. The Thai Navy had to spent considerable time and effort to correct some of these issues.

The harsh criticisms lead to many improvements in China's shipbuilding industry. By the mid-1990s, the Thai Navy was confident enough to order two enlarged 053 hulls (F25T), later named HTMS Naresuan and HTMS Taksin, to be fitted with western engines and weapon systems.

Upgrade
On 3 June 2011, Saab announced that it was awarded a contract for the upgrading of the two Naresuan class frigates. The scope of the upgrade will include Saab's 9LV MK4 combat management system, Sea Giraffe AMB, CEROS 200 fire control radar, EOS 500 electro-optics system and data link systems for communications with the newly acquired Royal Thai Air Force Erieye surveillance aircraft.

On 8 August 2012, DSCA announced Thailand's intention to acquire the Evolved Sea Sparrow missile and associated equipment to upgrade the frigates and a Letter of Offer and Acceptance was signed with Raytheon on 14 January 2013.