The imperial Japanese Navy’s effort to develop a motor torpedo boat (MTB) capable of standing up to the American PT boat was an unmitigated disaster. Hans Lengerer, in Motor Torpedo Boats of the Imperial Japanese Navy, Volume 1, 2007, notes on page 362, “The IJN interest in operational use of MTBs disappeared totally in the 1920s.” Earlier in the volume, Lengerer observed on page 262 that, “IJN tacticians had no interest in the MTB … only recognized (them) as torpedo chasers for (torpedo) firing tests.” Other naval historians, such as Richard Worth, have written on the subject and have similar damning conclusions.
Even the Japanese themselves recognized the shortcomings of their MTB program. What I quote here comes from captured and translated Imperial Japanese Navy documents. This material comes courtesy of David Dickson, who has a magnificent web site of translated WWII Japanese documents.
The material David used was captured on the Kwajalkin Atoll, March 29, 1944. The title of the document is “Battle Lessons Learned in the Greater East Asia War (Torpedoes),” Vol. VI, Annexed Vol. #1 (Motor Torpedo Boats Section) JICPOA Item 5782-A.
It starts with operational information about the IJN and the US Navy, then on page 10 it clearly states, “It is considered necessary to allocate an adequate number of PT boats as soon as possible.”
But it was not possible. The Japanese had ignored the MTB since the 1920s (see Lengerer above).
The litany of their troubles starts on page 14 of the captured document, under the title “Status of maintenance”:
a. Nevertheless, there are often leaks arising from loosening of the riveted parts of the hull/planking.
b. (E)ngine parts suffer vibration and friction wear at high speed operations, tho maximum speed is now 32-33 knots (designated speed 38 knots) Complete dismantling and repairs are necessary, yet this is not possible at present because of the state of facilities and the like.
c. Adjustment and maintenance of torpedoes cannot be said to be adequate to their function … the present dropping gear (for torpedoes) develops defects in the air connections, it is impossible to fire torpedoes …”
All of the craft built by the Japanese were more of a threat to their crews than to the enemy. The boats tended to catch fire, as noted on page 16 of the Japanese document: “The fire-resistant paints used on the walls of the engine room pool easily and have not been too successful.”
The boats were falling apart about as fast as they were being built. Pumps to move liquid coolant were placed in such a way that when the boats traveled at any significant speed they sucked in salt water, and the engines had to shut down immediately.
Crew preparedness was as bad as the boats themselves. Time allotted for training was exactly one month, which the report says, “covers only bare essentials.”
The last MTBs the Japanese built in 1944 had a top speed of 17. 5 knots. The engines did not burst into flame, so they were thought be “adequate.” The IJN never fielded an MTB force of any consequences. They did better with their “Shinyo” suicide boats – but not by much.
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