No.251-class auxiliary submarine chaser

The No.251 class auxiliary submarine chaser (第二百五十一号型駆潜特務艇,, Dai 251 Gō-gata Kusen-Tokumutei)[1] was a class of submarine chasers of the Imperial Japanese Navy (IJN), serving during World War II. 3 vessels were built in 1936 – 1939 under the Maru 2 Programme. They have two sub classes, this article handles them collectively.

Auxiliary Submarine Chaser No.251 in 1938
Class overview
Name:
  • No.251-class aux. submarine chasers
  • No.251-class (Project number K5A)
  • No.253-class (Project number K5B)
Builders:
Operators: Imperial Japanese Navy
Built: 1936 – 1939
In commission: 1937 – 1945
Planned: 3
Completed: 3
Retired: 3
Auxiliary Submarine Chaser No.253 in 1937
General characteristics
Type: Submarine chaser
Displacement: 170 long tons (173 t) standard
Length: 45.0 m (147 ft 8 in) overall
Beam: 4.80 m (15 ft 9 in)
Draught:
  • No.251 and No.252
  • 1.70 m (5 ft 7 in)
  • No.253
  • 1.73 m (5 ft 8 in)
Propulsion:
  • No.251
  • 2 × original MAN Mk.1 diesels
  • 2 shafts, 3,000 bhp
  • No.252
  • 2 × copied MAN Mk.1 diesels
  • 2 shafts
  • No.253
  • 1 × Kampon geared turbine
  • 2 × Kampon water tube boilers
  • 2 shafts, 3,000 shp
Speed: 23.0 knots (26.5 mph; 42.6 km/h)
Range: 800 nmi (1,500 km) at 14 kn (16 mph; 26 km/h)
Complement: 41
Armament:

Background
  • In 1934, the IJN planned an experimental model of a high-speed coast defense submarine chaser. The IJN wanted over 20 kn (23 mph; 37 km/h), however the Navy Technical Department (Kampon) had not designed this type of small craft and the needed high-powered diesel engines yet.
  • The IJN ordered the hull design from Thornycroft, and the high-powered diesel design from MAN, to study a small-sized high-speed boat.

Design
  • The Thornycroft drawings were not able to satisfy the IJN, because the design's center of gravity was too high, and had bad drainage. Kampon made a hull design based on the Hayabusa class torpedo boat instead.
  • The IJN was satisfied with MAN diesel specifications, however their designs were very complicated and very expensive. The IJN bought two engines and labeled them MAN Mk.1 diesel (マ式1号ディーゼル,, Ma-Shiki 1 Gō diesel). Further, the IJN ordered copies of these engines from Kawasaki Heavy Industries and Mitsubishi Heavy Industries.
  • Also, 1 vessel was equipped with a Kampon turbine, because the MAN diesel engines were unsuitable for a mass production.

Service
  • The IJN deployed them to a mine warfare school after having finished their examination, because they were too small.
  • They became a training ship of the mine warfare school, and they acted in Tokyo Bay.

Ships in classes

No.251-class
  • Project number K5A. 2 vessels were completed. They were equipped with MAN design diesels. The No.252 was equipped the copied MAN diesels by Kawasaki and Mitsubishi.

No.251
  • 14 December 1936: Laid down as the Submarine Chaser No.51 (第51号駆潜艇,, Dai 51 Gō Kusentei) at Nihon Kōkan, Tsurumi Shipyard.
  • 9 June 1937: Launched.
  • 30 September 1937: Completed.
  • 15 November 1940: Classified to the Auxiliary submarine chaser, and renamed Auxiliary Submarine Chaser No.51 (第51号駆潜特務艇,, Dai 51 Gō Kusen-Tokumutei).
  • (after): Assigned to the mine warfare school (Kurihama).
  • 30 April 1943: Renamed Auxiliary Submarine Chaser No.251 (第251号駆潜特務艇,, Dai 251 Gō Kusen-Tokumutei).
  • 28 August 1944: Classified to the Support vessel (tugboat), and renamed No.1658 (公称第1658号,, Kōshō-Dai 1658 Gō).
  • August 1945: The end of war at Uraga, later nothing more was heard.

No.252
  • 14 December 1936: Laid down as the Submarine Chaser No.52 (第52号駆潜艇,, Dai 52 Gō Kusentei) at Nihon Kōkan, Tsurumi Shipyard.
  • 25 August 1937: Launched.
  • 25 July 1939: Completed.
  • 15 November 1940: Classified to the Auxiliary submarine chaser, and renamed Auxiliary Submarine Chaser No.52 (第52号駆潜特務艇,, Dai 52 Gō Kusen-Tokumutei).
  • (after): Assigned to the mine warfare school (Kurihama).
  • 30 April 1943: Renamed Auxiliary Submarine Chaser No.252 (第252号駆潜特務艇,, Dai 252 Gō Kusen-Tokumutei).
  • 15 February 1944: Classified to the Support vessel (tugboat), and renamed No.1650 (公称第1650号,, Kōshō-Dai 1650 Gō).
  • August 1945: The end of war at Uraga, later nothing more was heard.

No.253-class
  • Project number K5B. 1 vessels was completed. She was equipped with Kampon turbine. She was classed in the No.251-class in the IJN official documents.

No.253
  • 9 January 1937: Laid down as the Submarine Chaser No.53 (第53号駆潜艇,, Dai 53 Gō Kusentei) at Ōsaka Iron Works, Sakurajima Factory.
  • 15 July 1937: Launched.
  • 31 October 1937: Completed.
  • 15 November 1940: Classified to the Auxiliary submarine chaser, and renamed Auxiliary Submarine Chaser No.53 (第53号駆潜特務艇,, Dai 53 Gō Kusen-Tokumutei).
  • (after): Assigned to the mine warfare school (Kurihama).
  • 30 April 1943: Renamed Auxiliary Submarine Chaser No.253 (第253号駆潜特務艇,, Dai 253 Gō Kusen-Tokumutei).
  • 15 February 1944: Classified to the Support vessel (tugboat), and renamed No.1651 (公称第1651号,, Kōshō-Dai 1651 Gō).
  • August 1945: The end of war at Uraga.
  • August 1946: Sink by unknown effect.

Footnotes
  1. At first No.51 class submarine chaser (第五十一号型駆潜艇,, Dai 51 Gō-gata Kusentei), until 15 November 1940.

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

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