The Tomozuru Incident – March 12,1934

IJN Tomozuru

The London Naval Treaty (Treaty for the Limitation and Reduction of Naval Armament) of April 16, 1924 set limits on construction of new naval capital units for the Royal Navy, United States Navy, Imperial Japanese Navy, French Navy and Italian Navy hopefully avoiding a naval arms race – one of the causes of World War One. Capital ship ratios of 5:5:3:1.75:1.75 (US Navy, Royal Navy, Japanese Navy,French Navy and Italian Navy respectively), infuriated the Japanese and forced them to discontinue the 8 – 8 Program (eight battleships and eight battlecruisers) that sought to provide a navy able to take on the United States Navy – already thought of as the most likely threat.

The solution chosen: pack new hulls with as much weaponry as possible. Since a smaller Navy was mandated great efforts were made to design ships qualitatively superior to the United States Navy’s. A series of formidable ships armed to the teeth was the result; among them the Yamato Class. The Japanese were well satisfied with new additions to the fleet until an incident on March 12,1934.

Light cruiser Tatsuta with torpedo boats Tomozuru and Chidori were on exercise early in the morning of the 12th when stormy weather caused them to set course for Sasebo Naval Base.

Between 0358 and 0412 Tomozuru capsized and was found floating capsized early that afternoon with the loss of 100 of the crew. “At the time of its loss, Tomozuru was low on consumables such as fuel or water that would have ballasted it and lowered its centre of gravity. On the other hand, munitions were fully loaded, so the situation was significantly worse than on its sea trials.”

Tomozuru’s loss sent a chill through the IJN’s naval architects. Her capsizing showed deficiencies in Japanese ship design as Tomozuru, a torpedo boat, had a weapon suite close to a destroyer with a light aluminum superstructure and a pronounced tendency to roll in heavy weather.Efforts were made to lower centers of gravity on ships in question: torpedo bulges were added.

Metacentric Center in line (G) at left. Out of line at right.

The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger metacentric height implies greater initial stability against overturning.

The following suffered from Tomozuru’s design flaws: aircraft carrier Ryuho, Mogami Class cruisers suffered strained hullsamd broken welds – main armament was changed and bulges added. Fubuki, Akatsuki and Hatsuharu Class destroyers, submarine tender Taigei and various classes of minelayers, minesweepers and patrol craft.Takao Class CA’s as well as other heavy cruisers with large super structures and heavy armament went back to the yards for modification. “The incident “severely challenged Japanese assumptions over the stability of their warships and prompted a major review of the design of all Japanese warships.”

“On December 29, 1934, the Japanese government gave formal notice that it intended to terminate the treaty. Its provisions remained in force formally until the end of 1936 and were not renewed.*

Tomozuru sinking – March 24, 1945

San Pedro News Pilot March 13, 1934

By Glenn Barb

SASEBO, Japan, March 14 (fP) Thirteen sailors, snatched from slow death described today the hours of ghastly suffering they withstood after the Japanese torpedo boat Tomozuru capsized, with 113 men aboard. Imprisoned in walls of steel, with scores of dead shipmates around them inside the storm-tossed, up-side-down craft, the men were near death when saved. Hope of finding any more of the 113 alive in the water-filled interior of the little fighting vessel passed as dawn broke over a macabre scene. At the drydock, where the craft was towed, blue-jackets were still working frantically at the tragic task of taking out bodies. Sixty-six bodies had been removed by midnight and carried to morgues through lines of weeping relatives. Women with babies strapped to their backs waited as close to the scene as authorities permitted. Three men escaped through a hatch before the craft was towed here. The other ten were taken out through a hole cut by rescurers. Most of them were unconscious. A naval officer quoted one of the men as saying: “When we felt the vessel turn over a small group of men in our compartment grasped hands and prepared to die together. We shouted Banzais for the emperor and for the Imperial navy.

“About noon, 30 hours after the accident, breathing became extremely difficult. Suddenly a gust of fresh air came through. The three of us were sufficiently revived to be able to open a hatch, through which we saw a diver beckoning to us. “We emerged and floated to the surface. It is a miracle that we are alive now.” Through the long hours of rescue work, while searchlights lighted the scene outside in a cold rain, a heartrending tapping could be heard from survivors in the darkness inside. Pumps worked at full speed to sluice water from the hull while air was forced in. The Tomozuru lay bottom up in the dock, just as she had been floated in, with her masts and funnel pointing downward. Tire vessel met disaster during maneuvers Monday off the Sasebo naval base. Waves swamped her, heavily laden with armament, despite machinery designed to prevent capsizing. A nava lboard of inquiry was appointed to study the cause of the disaster, which may become a national issue. Survivors said the skipper of the Tomozuru, Lieut. Commander Okuichi Iwase, was on the bridge when she turned over, and must have been swept to death.

*Evans, David & Peattie, Mark (1997), Kaigun: Strategy, Tactics and Technology in the Imperial Japanese Navy, 1887–1941, Annapolis: Naval Institute Press

Barb, Glenn, Torpedo Boat Sailors Fight With Death, San Pedro News Pilot, March 14,1934. California Digital Newspaper Collection


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