The No. 1-class submarine chaser was a class of submarine chasers of the Imperial Japanese Navy, serving during World War II. The Naval Technical Department (Kampon) made draft shallow to give them high speed. They achieved 24 kt speed hereby. No.1 and No.2 were completed in March 1934, and they were assigned to the 1st Subchaser Division, Yokosuka Naval Defence Squadron, however, because of their very shallow draft they lacked the rolling performance. This fact become evident after the Tomozuru incident.
The 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, resulting in a shorter vessel with a deeper draft. IJN record lists No.3 as a No.1-class boat but the ship is ofted listed separatedly, she laso had a different project designation than her half-sisters (K4 instead of K3).
No.1 and No.3 survived the war and were later scuttled by the British.
Ch-1 as built:
![[ img ]](http://i.imgur.com/dkoWmTA.png)
Ch-2 after refit:
![[ img ]](http://i.imgur.com/i9ziK6s.png)
Ch-3 as built:
![[ img ]](http://i.imgur.com/WQLQn0m.png)
