Japanese torpedo boat Tomozuru

The "Tomozuru" was one of four Japanese sclass|Chidori|torpedo boats, completed on February 24, 1934 and capsized in a storm on March 12, 1934, during training.

The significance of this incident is that it severely challenged Japanese assumptions over the stability of their warships and prompted a major review of the design of all Japanese warships. Existing vessels had their superstructures reduced and ships planned and under construction were redesigned during 1934-35. In particular the sclass|Mogami|cruiser|0 and sclass|Tone|cruiser|0 cruiser classes were significantly altered.

The instability of the "Chidoris" arose from Japanese efforts to circumvent the various naval treaties. They had designed small vessels of around 600 tons, but with the weaponry usual on a destroyer of twice the displacement. Weight had been saved by lighter construction but gun systems remained complex and heavy. After the launch of the lead ship, its high centre of gravity - even higher than feared - had been noted and efforts made to remedy this. High-speed sea trials showed her to be unstable, however, and further efforts were made to rectify the problem by adding bulges to the hull. Eventually "Chidori" satisfied the examiners and she was commissioned and the construction of the class, including "Tomozuru", proceeded.

In February 1934, "Tomozuru" joined the 21st Torpedo Flotilla at Sasebo. The training manoevres were made off Sasebo, in rough weather and at 3:25 am, they were abandoned. At 4:12 am, "Tomozuru"'s lights vanished and a search ensued. Eventually the capsized vessel was found at 1 pm and towed back to Sasebo. Sixteen crew members survived, but 100 died, including her captain.

At the time, the "Tomozuru" was low on consumables such as fuel or water that would have ballasted her and lowered her centre of gravity. On the other hand, munitions were fully loaded, so the situation was significantly worse than on her sea trials.

The ship was later repaired and saw service against China and in World War II. She was part of the naval support force for the invasion of Netherlands New Guinea in April 1942 and was present in the Banda Straits in July 1942.

"Tomozuru" was sunk on 24 March 1945, at Okinawa by U.S. carrier-based aircraft.

References

* [http://shippai.jst.go.jp/en/Detail?fn=0&id=CB1011021& Failure knowledge database]