All of this is absolutely insufficient because the newer Japanese transports (Hikawa Maru, Akagi Maru and such) were designed for speeds of 18-20 knots. You need at least 27-knot submerged speed capable submarines (comparable to Soviet November-class of 1957) to make ideas of intercepting and annihilating the Japanese transport convoys workable, even with aerial scouting. Actually aerial scouting would be of limited use too, because the Japanese were also invested heavily in long-range fighters (Ki-43 and A6M), and with rudimentary radar tech of 1941, the tracking of convoys from air at night was close to impossible, and unreliable in case of even cloudy weather. Simply if weather is good, your scout planes are shot down. If weather is bad, your scout planes are useless.
I understand this is a outright Dutch wank, but i.m.h.o. the most realistically engagement will not go the way you depicted, even if we assume the 8-knot speed of Japanese convoy is true (11-12 knots may be more appropriate given the circumstances of weather and relatively short route)
Most likely outcome is "after short-range torpedo from sweep has hit and damaged the light cruiser Naka, the Dutch submarines have failed to score any hits, being too busy trying to outmaneuver the escorts and get into firing positions. All torpedoes subsequently fired from long distances have failed to hit the targets."
Trurle:
Thank you for your reply, only disappointing you call it a wank, which it isn't.
First the strategy to use submarines as a main weapon to destroy military transport fleets in the Sea Straits approaching Java was real, conceived just after the Great War and was the main strategy for the next two decades.
Hence the fact that the Royal Dutch Navy had a very small number of very light cruisers and destroyers. The cruisers were only to protect the destroyers against enemy destroyers. Dutch destroyers were caring float planes, their main objective was to scout for the submarines. The relative large number of submarines.
Second the tactic to execute the strategy was developed and extensively trained during the next two decades. The last Division-Roedel exercise was performed in the summer of 1940.
The reason this strategy and tactic was abandoned, was due to the personal vision of the commander of the Dutch Royal Navy at that crucial time; Admiral Furstner. He was advocate of navalism, and for this reason he put all Dutch submarines under British command who, in line with their WW1 doctrine sent the submarines on solo mission with out any scouting of other submarines, surface vessels or airplanes. Admiral Furstner refused to send the submarines originally based in the Netherlands, the O-class boat, to reinforce the K -boats in the far East as was part of the submarine strategy.
The number of destroyed transport ships are based on the exceptional high hit rate in one attack of the O-16 (4 transports destroyed and 2 damaged) and the K-XIV (4 transports destroyed)
I am optimistic of the attrition rate even the Dutch doctrine was firing at a very close range with the calculated risk of being destroyed. On the other hand Dutch submarines would attack submerged when ever possible, and preferably at night. The Japanese submarine chaser and patrol boat were WW1 era destroyers and small versions of destroyers. There only weapon as with other navies at that time was throwing of depth charges at the estimated location of the submarine. . Use of active hydrophones (sonar) to locate enemy submarines was only later used by the Allies.
I am not arguing the fact that some transport ships could make 27 knots, the war ships of that time could make 32 knots. However this speed burns a lot of fuel.
There many other ships in the convoy who were not as fast and these slower ships determine the maximum speed of the fleet.
The Fleet was navigating in seas occupied by the enemy with risk of mine and non chartered sub-sea rocks. ( this was hitting an USS destroyer OTL)
The light cruiser "Naka" was destroyed in TL since it was part of the Japanese 4th destroyer flotilla. The Naka was a light cruiser, not a heavy armored battles ship, which made it plausible it could be destroyed by a salvo of 4 torpedo's from the bow as the Dutch submarines had. The attack of a Divison-roedel took place with 4 boats, each boat took its own target, which make it plausible that the first salvo's were hits and after the attack the boats would retreat in there attempt to avoid detection and destruction.
Your other argument was that Dutch subs are too slow and there for could not hit fast ships.
Dutch submarine resembled the German VIIB/C class with nearly the same speed. The kill rate of these 17 knot surface, 8 knot submerged boats was enormous it nearly brought Britain to starvation in 1940. The kill rate of the slightly larger and faster USS submarines was even higher and did starve Japan, but their speed never came higher than 21 knot surfaced.
The whole principle of submarines attack is not to out run enemy ships but to encounter them.
The hunting grounds of the Dutch submarines tactic were the Sea Straits of the Indonesian archipelago, which still are vast but are narrowed by numerous island within the straits.
Despite the heavy investment in long range fighters as you stated and the absence of radar or other sophisticated technologies, gave the reconnaissance planes on both sides during WW2 in the pacific a quit good detection score, without being shot down by sudden appearing long range fighters. You forget that the skies and seas are very large and that fighters did not have radar in 1941/1942 as well.