The was a class of submarine chasers of the Imperial Japanese Navy (IJN), serving during World War II. Three vessels were built in 1933-36 under the 1st Naval Armaments Supplement Programme (Japan, 1931), Maru 1 Programme and the 2nd Naval Armaments Supplement Programme (Japan, 1934), Maru 2 Programme. They have two sub classes.

Background

* In World War I, German U-boat raged. The Imperial Japanese Navy, IJN began maintenance of an anti-submarine boat as a lesson in this, because Japanese shoreline and sea-lanes were very long. The Imperial Japanese Navy, IJN had some submarine chaser type tugboats and yard ferries. However, they were small and their speed was low. * The Imperial Japanese Navy, IJN wanted to give the anti-submarine boats a speed of more than 20 knots, because their Kaidai class submarine, ''Kaidai III'' submarine already achieved a 20kt surfaced.

Design

* The Imperial Japanese Navy Technical Department, Naval Technical Department (Kampon) made draft shallow to give them high speed. They achieved 24 kt speed hereby. * The ''No. 1'' and the ''No. 2'' were completed in March 1934, and they were assigned to the 1st Submarine chaser, Submarine Chaser Division, Yokosuka Naval Defence Squadron. * However, because of their very shallow draft they lacked the rolling performance. This fact become evident after the Chidori class torpedo boat, ''Tomozuru'' incident. * The Japanese torpedo boat Tomozuru, ''Tomozuru'' incident affected the ''No. 1''-class. The ''No. 1'' and the ''No. 2'' were sent to the Uraga Dock Company in July 1934, and repairs were started. They were equipped 80 tons ballast and mounted a ballast keel. The drawings for the ''No. 3''-class boat was also revised.

Service

* Late 1934, Repairs were completed. * October 1936, The ''No. 3'' assigned to 1st SchDiv. They always shared an action afterward. * In 1938, the 1st SchDiv was transferred to the No. 1 Base Force (Shanghai). * On 5 September 1941, the No. 1 Base Force was transferred to the IJN 2nd Fleet, 2nd Fleet. * In December 1941 – March 1942, the 1st SchDiv engaged to the Battle of the Philippines (1941–42), Battle of the Philippines and Dutch East Indies campaign. * On 10 March 1942, the 1st SchDiv was transferred to the No. 21 Special Base Force (Surabaya), Southern Expeditionary Fleet (Imperial Japanese Navy)#2nd Southern Expeditionary Fleet, 2nd Southern Expeditionary Fleet, Southwest Area Fleet. * On 1 May 1942: The 1st SchDiv was dissolved. They spent all their time for escort operations in the Java Area.

Ships in classes

''No.1''-class

* Project number was K3. 2 vessels were built under the Maru 1 Programme. They equipped the MV hydrophone by Raytheon, Submarine signal company and latest active sonar the Type 93.

''No.3''-class

* Project number was K4. Only 1 vessel was built under the Maru 2 Programme. The ''No. 3'' was equipped the French SCAM active sonar and latest hydrophone the Type 93. The ''No. 3'' was classed in the ''No. 1''-class in the IJN official documents.

Photos

Image:IJN No2 submarine chaser around 1934.jpg, ''No. 2'' in 1934 Image:IJN No3 Submarine Chaser 1936.jpg, ''No. 3'' in 1936

Footnotes

Bibliography

* ''Ships of the World special issue Vol. 45, Escort Vessels of the Imperial Japanese Navy'', , (Japan), 1996. * ''The Maru Special, Japanese Naval Vessels No. 49, Japanese submarine chasers and patrol boats'', (Japan), 1981. {{DEFAULTSORT:1 World War II naval ships of Japan Submarine chaser classes Submarine chasers of the Imperial Japanese Navy