Thailand: State of Submarine Forces in ASEAN 2023 – 1

The first ASEAN country submarine force in my series concerns Thailand. 

1 submarine on order

S26T model Image: courtesy Asianmilitayreview.com
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Matchanu-class S26T variant of the Type 039A Yuan.

1 on order, 2 tentative

Displacement 2,550 tonnes

Selected 2015, First boat ordered 2017 

May be delivered: 2025

Price - US$380 million
 

The Royal Thai Navy (RTN) is scheduled to receive its first submarine in 2023, but what is not common knowledge is that the Royal Thai Navy is actually the oldest submarine service in ASEAN, as its predecessor, the Royal Siam Navy, operated submarines from 1938 to 1951.

 

In 1935 Thailand acquired four 350 tonnes coastal submarines from Mitsubishi Heavy Industries, which were delivered by 1938. This first/original Matchanu-class served through WW2, but as Japan was disarmed post-war, they became unserviceable. They were scrapped following a failed coup attempt by Thai naval officers in the 1951 Manhattan Rebellion.
 

This explains the deep seated desire of the RTN to operate submarines. 
 

In 2015, the RTN held a tender process and selected the S26T (an export variant of the Type 039A Yuan), as China Shipbuilding & Offshore International Company (CSOC) offered a very low total price of US$1 billion for all 3. The RTN secured a $390 million procurement contract with CSOC in 2017 for the first boat, but the follow up order for the next two boats has been delayed due to public discontent over the cost during the COVID-19 pandemic.
 

Various reports have stated that the Thai Navy requires submarines for operations in the Andaman Sea and the Gulf of Thailand, as well as to ‘keep up with the neighbors’, with Malaysia’s 13 year old Scorpenes specifically cited.
 

With a maximum depth of 85 metres, the Gulf of Thailand is relatively shallow for modern submarine operations. While the Andaman Sea is dominated by Indian military bases in the Andaman and Nicobar Islands, where up 32 Indian Navy ships are based. Also infrastructure upgrades have been completed to accommodate Indian jet fighter and P8I Poseidon patrol aircraft detachments.
 

In February 2022 it emerged that CSOC specified German-made MTU 396 submarine diesel engines in the Thai contract, which have been subject to an EU arms embargo on China since 1989. While CSOC has offered Chinese-built CHD620 engines as replacements (or a pair of decommissioned PLAN boats), the RTN is considering its options, including canceling the deal.
 

The engine issue has been reported as settled by April 2023, with ‘Chinese authorities guaranteeing the safety of the engines’ and the Thai Navy estimating the first S26T might be delivered by 2025. Pakistan’s Hangor-class S26T deal is also mentioned - that deal might also be delayed due Chinese CHD620 diesels replacing the previously expected MTU 396s.  

According to Asiamilitaryreview.com, quoting CSOC specifications, the S26T has a displacement of 2,550 tonnes (this may be surfaced displacement as the submerged figure for a Chinese Navy Type 039A is 3,600 tonnes). A S26T also has a nominal crew of 38, with accommodations for 46 bunks, and a separate commander’s quarters. Claimed maximum endurance is 65 days at sea with transit distances of up to 8,000nm (14,800km). These specifications mean that an S26T could easily transit from the RTN’s main naval base at Sattahip to patrol areas in the South China Sea or Bay of Bengal with a small Royal Thai Navy SEALs contingent.

Shawn Chung
May 26, 2023