No.1-class submarine chaser

(left to right) No. 1, No. 2 and No. 3 in 1938
Class overview
Name:	No. 1-class submarine chasers • No. 1-class (Project nomber K3) • No. 3-class (Project number K4)
Builders:	Uraga Dock Company Tōkyō Ishikawajima Shipyard Asano Shipyard
Operators:	Imperial Japanese Navy
Succeeded by:	No. 4-class
Cost:	1,525,700 JPY (No. 1-class) 1,530,000 JPY (No. 3-class)
Built:	1933 – 1936
In commission:	1934 – 1946
Planned:	3
Completed:	3
Lost:	1
Retired:	2
General characteristics No. 1-class
Displacement:	266 long tons (270 t) standard 280 long tons (284 t) trial and after late 1934 377 long tons (383 t) trial
Length:	65.30 m (214 ft 3 in) overall 64.00 m (210 ft 0 in) waterline
Beam:	5.90 m (19 ft 4 in)
Draught:	1.43 m (4 ft 8 in)
Propulsion:	2 × Kampon Mk.22 Model 8 diesels 2 shafts, 3,400 bhp
Speed:	24.0 knots (27.6 mph; 44.4 km/h) and after late 1934 21.1 knots (24.3 mph; 39.1 km/h)
Range:	1,500 nmi (2,800 km) at 14 kn (16 mph; 26 km/h)
Complement:	65
Armament:	• 2 × 40 mm heavy machine guns • 36 × depth charges • 1 × depth charge thrower • 1 × Type 93 active sonar • 1 × MV hydrophone
General characteristics No. 3-class
Displacement:	270 long tons (274 t) standard 285 long tons (290 t) trial
Length:	56.10 m (184 ft 1 in) overall 55.00 m (180 ft 5 in) waterline
Beam:	5.60 m (18 ft 4 in)
Draught:	2.10 m (6 ft 11 in)
Propulsion:	2 × Kampon Mk.22 Model 6 diesels 2 shafts, 2,500 bhp
Speed:	20.0 knots (23.0 mph; 37.0 km/h)
Range:	1,500 nmi (2,800 km) at 14 kn (16 mph; 26 km/h)
Complement:	60
Armament:	• 2 × 40 mm heavy machine guns • 36 × depth charges • 2 × Type 94 depth charge projectors • 1 × depth charge thrower • 1 × French SCAM active sonar • 1 × Type 93 hydrophone

The No. 1-class submarine chaser (第一号型駆潜艇,, Dai 1 Gō-gata Kusentei) 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 Maru 1 Programme and the Maru 2 Programme. They have two sub classes, this article handles them collectively.

Background

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

Design

• The 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 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.

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 2nd Fleet.
• In December 1941 – March 1942, the 1st SchDiv engaged to the 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), 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 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

• 

  No. 2 in 1934

• 

  No. 3 in 1936

Footnotes

1. ↑ Submarine chaser No. 1 (第1号駆潜艇, Dai 1 Gō Kusentei). The same shall apply hereinafter.

Bibliography

• Ships of the World special issue Vol. 45, Escort Vessels of the Imperial Japanese Navy, "Kaijinsha". , (Japan), 1996.
• The Maru Special, Japanese Naval Vessels No. 49, Japanese submarine chasers and patrol boats, "Ushio Shobō".  (Japan), 1981.