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    Info on Japanese Midget Submarine

    Bob Lyons

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    Japanese raiders rest in watery tomb

    Ian McPhedran

    May 22, 2007 12:00am

    Article from: h14_heraldsun.gif</IMG>THE bodies of two Japanese sailors who conducted an audacious World War II raid in Sydney Harbour will remain entombed in a mini-submarine off Sydney's northern beaches.

    The wreck of the M-24 lies in 54m of water about 5km off Bungan Head, where it sank on the night of May 31, 1942.

    The mystery of the last of the three mini-subs that brought war to a disbelieving city may never be fully solved.

    "These were the elite of the elite in the Japanese navy," said Australian War Memorial historian John White.

    "They were highly trained, very fit, and expert navigators."

    Lt Katsuhisa Ban and Petty Officer Mamoru Ashibe piloted their craft around nets strung across the harbour and past numerous lookout posts to fire two torpedoes at the heavy cruiser USS Chicago, moored off Garden Island.

    One struck HMAS Kuttabul nearby, killing 19 sleeping Australian sailors and two Britons.

    Ban and Ashibe then submerged in a bid to escape to one of five submarine mother ships waiting off Port Hacking.

    Two other Japanese subs were caught; their crews committed suicide. Ban and Ashibe's battery-powered mini-sub sailed about 13km northeast before it sank.

    In November last year, recreational divers found the wreck, partly covered by sand.

    The commander of navy clearance diving team 1, Lt-Cdr Etienne Mulder, said everything pointed to the bodies still being inside.

    A ladder would have been pulled down had the crew climbed through an escape hatch in the conning tower.

    "That ladder is still in the up position, as far as we can tell," he said.

    He said the Sydney harbour raid had been a "one way ticket". "The chances of you coming back aren't very high."

    He said it was amazing how few people knew that the M-24 was the sub that sank the Kuttabul.

    Questions remain about the fatal mission:

    WHY were scuttling charges not fired?

    WHY was the boat heading north, away from the mother ship?

    WAS she damaged or did she run out of power?

    Able Seaman Ryan Dart, from Ballina in northern NSW, made his fourth and final dive to the wreck yesterday.

    The young sailor carried a jam jar down into the dark water and scooped up some sand close to the sub. It will be presented to the brothers of Lt Ban and Petty Officer Ashibe.

    The wreck is a historic shipwreck and a protected zone, monitored by a video alarm system.

    THE NSW Heritage Office, in conjunction with the National Parks and Wildlife Service, will conduct guided ferry tours of the key sites of the 1942 midget submarine attack to mark the 65th anniversary on May 31.

    Edited by Bob Lyons
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    Hi Bob,

    Would you know if this mini sub is same type that was sent against Pearl Harbor on December 7, 1941? Was there more than one type of mini sub in the Japanese Navy at this time of the war? Just curious!


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    From 1934 to 1944, the Japanese Navy built several dozen midget submarines for combat use. They were originally intended to be carried by larger Japanese ships and deployed in the path of an enemy fleet, where they would disrupt its operations with torpedo attacks. However, during the Second World War, the midgets were used for special operations against ships in enemy harbors, among them the 7 December 1941 Pearl Harbor attack and May 1942 raids on Sydney, Australia, and Diego Suarez in the Indian Ocean. The boats also were employed off Guadalcanal in 1942-43, where they achieved modest success against U.S. shipping, and as shore-based defensive units in the Aleutians and elsewhere in the Pacific war zone.

    Type A midgets displaced 46 tons, were 78 feet long and carried two 45cm (17.7") diameter torpedoes. Powered by electric motors, they were capable of very high speeds (about 20 knots), but had very limited range. To increase endurance, the prototype Type B and production Type C boats were fitted with a diesel engine to recharge their electric batteries. They had an additional crew member, were slightly longer and heavier, but otherwise resembled the Type A.

    After Pearl Harbor, modifications were made to the Type A designed and this variant was designated Type A Kai 1 (improved version 1). The modifications included the fitting of an improved gyro compass, serrated net-cutters on the bow and conning tower, a sled-like bow guard for maneuvering over obstacles and a propeller guard to prevent entanglement in nets or cables. The Sydney, Diego Suarez and Guadalcanal midget submarines were of this type.

    The Otsu Gata (Type B) midget submarine was the first version fitted with a diesel (40 hp / 25 kw) and a slightly longer hull to accommodate it. All specifications were same as the Type A, except the length (24.9 m vs. 23.9 m), displacement (47 tons vs. 46), and surface speed (6 knots vs. 19). The Type B's diesl engine allowed a range of 500 nautical miles (nms) at 6 knots (surfaced), 15.8 nms at 9 knots and 84 nms at 6 knots underwater on the electric motor.

    Four Type A midgets are on display around the world. They are located at:

    - National Museum of the Pacific War, Fredericksburg, Texas

    - Nautilus Memorial Submarine Force Library and Museum, Groton, Connecticut

    - JMSDF Naval Tactical School No. 1, Eta Jima, Hiroshima, Japan

    - Australian War Memorial, ANZAC Hall, Canberra

    Approximately sixty production Type A midget submarines were built between 1934 and 1942, and given alpha-numeric names in the "Ha" series (Ha-1 through Ha-52 and Ha-54 through possibly Ha-61). The single Type B (Ha-53) and fifteen Type Cs (Ha-62 through Ha-76) were built in 1943-44.

    Type C

    Edited by Laurence Strong
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    The Koryu (Type D) Tei Gata was an improved version of the Type C midget. Type D's were equipped with more powerful diesels and electric motors and could recharge their batteries faster. These changes again tripled their range. They were four feet longer, weighed 60 tons and could dive to 328 feet. The first Type D, HA-101, was completed in May '44 and accepted into service on 28 May 1945. By war's end, 115 were completed and another 496 hulls were in various stages of construction. At least five Type D's were lost in operations at Okinawa in March 1945.

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    Kairyu class submarine

    The small "Kairyu" type midget submarines were intended for local defense against the prospective invasion that confronted Japan in 1945. The design, which featured diving planes mounted on the hull amidships, was tested in 1943-44, with production beginning in early 1945. A total of 760 boats were planned. Over 200 were delivered by August 1945, the great majority of these having been constructed at Yokosuka. Though originally designed to carry two 45cm (17.7") diameter torpedoes externally, a torpedo shortage caused most, if not all, of these submarines to be fitted with an internal warhead, for employment on suicide missions.

    The "Kairyu" type midgets displaced somewhat over 19 tons. Length appears to have varied, with the largest being about 57 feet long. Hull diameter was 4 1/2 feet, creating a tight fit for the two-man crew. Propulsion was an 80 horsepower electric motor with an 85 HP gasoline engine for battery charging and surface running. Speed was 10 knots submerged and 7.5 knots on the surface. Some units, used for training, had a second periscope mounted at the rear of their streamlined conning tower.

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    By late 1944, the war situation had deteriorated for Japan to the point where extraordinary measures were seen as offering the only way out of an increasingly grim military predicament. Thus, with the invasion of the Phillipines, the Japanese first formulated and implemented 'Special Attack' tactics in the form of suicide aircraft attacks: the kamikazes. In short order, Japan began applying the same doctrine in the creation of new weapons systems. Notable among these was the kaiten ("Turning of the Heavens") suicide submarine.

    The kaiten was aptly described by Theodore Cook as "not so much a ship as an insertion of a human being into a very large torpedo. The guts of the beast was a standard Type-93 24" torpedo, with the mid-section elongated to create the pilot's space. He sat in a canvas chair practically on the deck of the kaiten, a crude periscope directly in front of him, and the necessary controls close to hand in the cockpit. Access to the kaiten was through hatches leading up from the sub and into the belly of the weapon. The nose assembly was packed with 3000+ pounds of high explosive; the tail section contained the propulsion unit. All in all, it was a crude, nasty way for a man to kill himself. The kaiten I saw at Etajima absolutely gave me the creeps."

    My info was sourced from several internet site's.

    Edited by Laurence Strong
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    WOW! Thank you Laurence for that VERY detailed explaination of the evolution of the Japanese mini sub. A lot of information I had not known about. I appreciate the time you spent educating me. :beer:


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