Thailand's Mini-submarine Requirements - Possible Foreign Suppliers

A newbuild South Korean HHI HDS-400 (400 tonne surfaced or submerged?) mini-sub may be what Thailand may buy. Or perhaps a modernised version of the 1980s Russian Piranha/Losos mini-sub (photo above). Thailand's requirements may be - operate in very shallow water, Special Operations and generalised training capabilities. 

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The Thai government in mid July 2018 approved an (equivalent to) US$5.8m project to design a mini-submarine. It is early days, but so far the Thai project is named the Chalawan-class. Requirements are reported as:
-  150-300 tonne surfaced displacement
-  crew of 10, and
-  300 nautical mile range. 
(Comment - Lithium-ion batteries only, with no diesels, might be sufficient for a range so short.)

COMMENT (Speculative of course!)

These miniature submarines may be designed for the very shallow waters of the Gulf of Thailand, waters probably too shallow for the 3 future Chinese built Yuan derivative S26T submarines, that Thailand is buying. Minisubmarines generally can also serve as Special Forces transporters and cheap training platforms for crews before they man larger subs.

WHAT COUNTRIES MAY ASSIST THAILAND?

From SSMs records both Germany and South Korea have developed plans for submarines in the 150 – 300 tonnes range. More substantially South Korea has actually built and operated 175 tonne Dolgorae-class submarines with 14 crewmen. 

South Korea's remaining two Dolgoraes, launched 1990-1991 will reach the end of their usual South Korean Navy operational lives by 2020. Perhaps they could be (or will be) sold to Thailand, within the next 2 years for Thailand's floated US$5.8 million. Maybe logical as less than $6 million won't buy much submarine!

Interestingly in September 2015 Wiki and Janes reported that South Korea's Hyundai Heavy Industries (HHI) started construction of a single 40 metre long HDS-400 mini submarine for an unnamed naval customer.^[2] 

[Comment: could that customer be Thailand? Or if that customer (maybe the South Korean Navy?) dropped out has HHI offered the sub to Thailand?] 

Russian built and operated Piranha (“Losos”) minisubs also provide an option Russia could build for Thailand directly or pass designs to China for supply to Thailnd. Significantly specs for the Piranha/Losos coincide closely with Thailand’s stated requirements. With Piranhas/Losos:
-  Being 218 tons (surfaced)

-  Crew of 9
-  With a short 10 day endurance (enough for a Thai mission to Myanmar or Cambodian waters and

    back).

China has the industrial base and SSK building experience to also design such submarines (or adapt Russian designs) then make the parts for Thailand to assemble.

Pete