Prashanth Parameswaran writing for The Diplomat, July 16, 2015 has neatly summed up Thailand's "do we need submarines" debate http://thediplomat.com/2015/07/is-chinas-new-submarine-deal-with-thailand-now-in-peril/:
"The decision to place a hold on this particular submarine deal — which would cost Thailand 36 billion baht ($1.06 billion) for [the 3 Chinese S26T submarines on offer] — is also not altogether unexpected. The purchase has run into fierce opposition within Thailand among politicians and activists, many of whom have raised doubts about whether the country really needs submarines and suggested that the money would be better spent on more urgent priorities like boosting the economy. Given all this, it is not surprising that [Thai Defence Minister] Prawit referenced the need to take into account “the public reception” to the submarine purchasing plan. While he was not specific on how this would be done, his suggestion that the Navy is “yet to conduct a thorough study” on how suitable and cost-effective the submarines are – which directly contradicts his earlier statement that Chinese submarines were clearly the most cost-effective – indicates that this may require not only more time, but further examination."
Thailand's surrounding sea depths (see map above) severely limit operations for any future Thai submarine service. The lightest blue (almost white) for the seas/oceans on the map indicate sea depths of less than 200 meters (m) around Thailand's whole coastline. This is for Thailand's west coast (Andaman Sea) and especially east coast (Gulf of Thailand - out to hundreds of kilometers). According to Wikipedia, the Gulf of Thailand has an average depth of 58m, which is greater than the average depth of the Baltic Sea (55m) but instead of a maximum depth of 459m in the Baltic Sea, the maximum depth in the Gulf of Thailand is only 85m. The Baltic therefore provides quite deep places for submarines to sit on the seafloor and hide - the Gulf of Thailand does not. (Map courtesy US National Oceanic and Atmospheric Administration (NOAA)).
Perhaps Thailand should be considering submarines of 500 tons or less. Mini-submarines are harder to see in shallow water and are several hundred $millions cheaper for three. Perhaps South Korea's 200 ton Dolgorae class or perhaps a slightly larger 300 ton submarine.
Thailand's major strategic issues are on land. Thailand's politico-military power is well served by non-aligned neutrality, overall good relations with its immediate Southeast Asian neigbours (Malaysia, Myanmar, Laos) tense but manageable relations with Cambodia. Indonesia is a middle power with no tensions with Thailand(?) Australia is no threat. China and India are the great regional powers.
The lack of clearly defined threats that Thai submarines could counter has been at the heart of the "Do we need submarines" debate in Thailand for decades. So why does Thailand want submarines? To protect fisheries? Anti-drug smugglers? To intercept refugee boats? For intelligence gathering? To satisfy an ally who demands or expects submarine activities?
To detect and intercept fishing boats, drug smuggling boats and refugee boats best requires patrol boats. Patrol boats do not need to look through a periscope or hide. Patrol boats operate by having constant radio contact, radar and visual sight. Satellite links help. Thailand's patrol boats and larger ships deter by being seen.
The Thai Navy is big enough to handle navies of its immediate neigbours. Is India a threat? Or is the possibility of future unimagined threats sufficient to justify a submarine purchase?
Is China the main threat? If so buying submarines off China builds military bilateral relations - cash for good relations. China is probably no longer prepared to provide soft loans or write off debt-costs. With slower Chinese growth and China's 2015 financial/stockmarket shocks China is probably expecting hard currecy payment for the three submarines. Has that demand hindered the Thai-China submarine deal?
China has already excessively reduced the price per submarine (now US$333 million with training + spares included). The standard international price for a submarine is around US$500 million and then AIP costs extra. Training and spares over several years is often another $500 million per sub.
Additional reasons to have submarines are to keep up with the neighbours in a regional submarine race - for political and strategic power, deterrence and prestige.
Looking internally into Thailand it needs to be asked "Has 2014's political crisis given the Army power that makes the Navy jealous?
Is the Navy therefore entitled to have an expensive weapons system because the Navy does not have the same level of power?"
Please connect with Submarine Matters:
Thailand Puzzling Whether to Buy Chinese Submarines, July 16, 2015
Thailand may eventually purchase two submarines, March 25, 2015.