Etorofu-class escort ship

The Etorofu-class escort ships (択捉型海防艦, Etorofu-gata kaibōkan) were a group of fourteen kaibōkan escort vessels built for the Imperial Japanese Navy during World War II. Eight of the fourteen ships were sunk during the war. The class was also referred to by internal Japanese documents as the "Modified A-class" coastal defense vessel (甲型海防艦, Kō-gata kaibōkan).

Etorofu in 1943
Class overview
Operators	Imperial Japanese Navy  Republic of China Navy  People's Liberation Army Navy
Preceded by	Shimushu class
Succeeded by	Mikura class
Built	1942–1944
Completed	14
Lost	8
General characteristics
Type	Escort vessel
Displacement	870 long tons (884 t)
Length	77.7 m (255 ft)
Beam	9.1 m (29 ft 10 in)
Draught	3.05 m (10 ft)
Speed	19.7 knots (22.7 mph; 36.5 km/h)
Complement	150
Armament	3 × 120 mm (4.7 in)/45cal DP guns 4 × Type 96 25 mm (0.98 in) AA guns, later up to 15 6 × depth charge throwers 36 × depth charges initially, but later up to 60 1 × 81 mm (3.2 in) mortar

Background

The Shimushu-class kaibōkan, as with the Chidori-class torpedo boat, was a consequence of the 1930 London Naval Treaty, which placed limitations on the total destroyer tonnage the Imperial Japanese Navy was permitted. One way in which the treaty could be circumvented was to use a loophole in the treaty which permitted ships of between 600 and 2,000 tons, with no more than four guns over 76 mm (3 in), no torpedoes, and with a maximum speed of no more than 20 knots (37 km/h; 23 mph). A new class of vessel was designed to use this loophole, and was given the obsolete designation of kaibōkan (Kai = sea, ocean, Bo = defence, Kan = ship), which had previously been used to designate obsolete battleships which had been reassigned to coastal defense duties. Immediately before the start of then Pacific War, the Imperial Japanese Navy suddenly decided to give more priority to convoy escorts, possibly in light of the ongoing successes of German U-boats against British shipping in the Atlantic. As the Shimushu class was not suited for mass-production and took too long to build, the 1941 Rapid Naval Armaments Supplement Programme authorized thirty modified versions of the Shimushu class, which were designated the Etorofu class.^[1] However, sixteen of the projected thirty ships were subsequently re-ordered to the subsequent Mikura, Hiburi or Ukura designs.

Production began between February 1942 and August 1943. Despite simplification, the design was still too complex for mass production and one of the ships was not completed until early 1944.^[1]

Description

The Etorofu class was almost identical to the Shimushu class but with a simplified bow, stern and bridge structure to facilitate production. The ships measured 77.72 meters (255 ft 0 in) overall, with a beam of 9.1 meters (29 ft 10 in) and a draft of 3.05 meters (10 ft 0 in).^[2] They displaced 880 metric tons (870 long tons) at standard load and 1,040 metric tons (1,020 long tons) at deep load. The ships had two diesel engines, each driving one propeller shaft, which were rated at a total of 4,200 brake horsepower (3,100 kW) for a speed of 19.7 knots (36.5 km/h; 22.7 mph). The ships had a range of 8,000 nautical miles (15,000 km; 9,200 mi) at a speed of 16 knots (30 km/h; 18 mph).^[3]

As with the Shimushu class the main battery of the Etorofu class consisted of three Type 3 120-millimeter (4.7 in) guns in single mounts, one superfiring pair aft and one mount forward of the superstructure. Anti-aircraft protection was by four Type 96 25-millimeter (1.0 in) anti-aircraft guns in two twin-gun mounts abreast the bridge. However, for a ship supposedly designed for convoy escort, only one Model 94 depth charge launcher was installed on the quarterdeck along with a Model 3 loading frame. The number of depth charges was initially 36, but this was increased to 60 while the ships were still in production, which necessitated the deletion of the two paravanes initially in the design for minesweeping. The ships were also equipped with a Model 93 sonar and a Type 93 hydrophone.^[1]

During the Pacific War, the number of Type 96 anti-aircraft gun was increased to five triple-mounts and a varying number of single-mounts, up to 15 in total by August 1943. A Type 22 and Type 13 radar were also installed. A Type 97 81-millimeter (3.2 in) trench mortar was also installed front of the bridge^[3]

Operational service

The Etorofu class proved to be an inadequate design by the time the final units entered service in 1944. Their speed was slower than most submarines, and with only one depth charge projector, their combat capability against the increasingly effective United States Navy submarine forces was ineffective. The Etorofu-class vessels were mostly deployed to the South China Sea or East China Sea as convoy escorts, but few recorded any attacks against Allied submarines. Conversely, six of the 14 ships in the class were sunk by American submarines. Of the six survivors, three were used as repatriation ships after the war, and were subsequently given as prize of war to Allied navies.^[1]

Ships in class

Thirty ships (numbered #310 to #339) were included in the Rapid Naval Armaments Supplement Programme in 1941. These are listed below with the shipyard to which each was allocated:

Number Name Builder #310 Etorofu Hitachi-Sakurajima Shipyards #311 Matsuwa Mitsui-Tamano Shipyards #312 Sado NKK-Tsurumi Shipyards #313 Oki Uraga Dock Company #314 Matsure Hitachi-Sakurajima Shipyards #315 Iki Mitsui-Tamano Shipyards #316 Tsushima NKK-Tsurumi Shipyards #317 Wakamiya Mitsui-Tamano Shipyards #318 Hirado Hitachi-Sakurajima Shipyards #319 Fukae Uraga Dock Company #320 Mikura NKK-Tsurumi Shipyards #321 Amakusa Hitachi-Sakurajima Shipyards #322 Miyake NKK-Tsurumi Shipyards #323 Manju Mitsui-Tamano Shipyards #324 Awaji Hitachi-Sakurajima Shipyards

Number Name Builder #325 Kanju Uraga Dock Company #326 Nōmi Hitachi-Sakurajima Shipyards #327 Kurahashi NKK-Tsurumi Shipyards #328 Hiburi Hitachi-Sakurajima Shipyards #329 Chiburi NKK-Tsurumi Shipyards #330 Kasado Uraga Dock Company #331 Yashiro Hitachi-Sakurajima Shipyards #332 Ukuru NKK-Tsurumi Shipyards #333 Daitō Hitachi-Sakurajima Shipyards #334 Kusagaki NKK-Tsurumi Shipyards #335 Okinawa NKK-Tsurumi Shipyards #336 Amami NKK-Tsurumi Shipyards #337 Aguni NKK-Tsurumi Shipyards #338 Shinnan Uraga Dock Company #339 Shōnan Hitachi-Sakurajima Shipyards

While fourteen of the above ships were completed to the Etorofu design, eight ships - Mikura (#320), Miyake (#322), Awaji (#324), Nōmi (#326), Kurahashi (#327), Chiburi (#329), Yashiro (#331) and Kusagaki (#334) - were altered to be built to the Mikura design; three ships - Hiburi (#328), Daitō (#333) and Shōnan (#339) - were altered to be built to the Hiburi design; and five ships - Ukuru (#332), Okinawa (#335), Amami (#336), Aguni (#337) and Shinnan (#338) - were altered to be built to the 'Ukuru design. The fourteen completed to the (original) Etorofu design were as follows:

Kanji	Name	Builder	Laid down	Launched	Completed	Fate
択捉	Etorofu	Hitachi-Sakurajima Shipyards	23 February 1942	29 January 1943	15 May 1943	Ceded to the United States, 1946. Scrapped 1947
松輪	Matsuwa	Mitsui-Tamano Shipyards	20 April 1942	13 November 1942	23 March 1943	Sunk by USS Harder on 22 August 1944, Hidai Bay, Philippines [14-15N, 120-25E]
佐渡	Sado	NKK-Tsurumi Shipyards	21 February 1942	28 November 1942	27 March 1943	Sunk by USS Haddo on 22 August 1944, Hidai Bay, Philippines [14-15N, 120-25E]
隠岐	Oki	Uraga Dock Company	27 February 1942	20 October 1942	28 March 1943	Ceded to Republic of China Navy as Gu An (固安) in August 1947, captured by PLAN and renamed Chang Bai (长白) in 1949, scrapped 1982
六連	Mutsure	Hitachi-Sakurajima Shipyards	25 July 1942	10 April 1943	31 July 1943	Sunk by USS Snapper on 2 September 1943, Philippine Sea [08-40N, 151-31E]
壱岐	Iki	Mitsui-Tamano Shipyards	2 May 1942	5 February 1943	31 May 1943	Sunk by USS Raton on 24 May 1944, 150 miles W of Sarawak
対馬	Tsushima	NKK-Tsurumi Shipyards	20 June 1942	20 March 1943	28 July 1943	Ceded to Republic of China Navy as Lin An (臨安) 31 July 1947, scrapped 1963
若宮	Wakamiya	Mitsui-Tamano Shipyards	16 July 1942	19 April 1943	10 August 1943	Sunk by USS Gato on 24 May 1944, East China Sea [28-38N, 122-05E]
平戸	Hirado	Hitachi-Sakurajima Shipyards	2 November 1942	30 June 1943	28 September 1943	Sunk by USS Growler on 12 September 1944, South China Sea [17-54N, 114-49]
福江	Fukae[4]	Uraga Dock Company	30 October 1942	2 April 1943	28 June 1943	Ceded to UK in July 1947, scrapped
天草	Amakusa	Hitachi-Sakurajima Shipyards	5 April 1943	30 September 1943	20 November 1943	Sunk by Royal Navy aircraft 9 August 1945, Onagawa, Japan
満珠	Manju	Mitsui-Tamano Shipyards	15 February 1943	31 July 1943	30 November 1943	Scrapped 1946
干珠	Kanju	Uraga Dock Company	8 April 1943	7 August 1943	30 October 1943	Scuttled after mine damage, 15 August 1945, near Wonson, Korea [39-10N, 127-27E.]
笠戸	Kasado	Uraga Dock Company	10 August 1943	9 December 1943	27 February 1944	Scrapped 1948

Notes

1. Stille, Mark (2017). Imperial Japanese Navy Antisubmarine Escorts 1941–45. Oxford, UK: Osprey Publishing. pp. 20–24. ISBN 978-1-4728-1817-1.
2. Chesneau, p. 205
3. Jentschura, Jung & Mickel, p. 187
4. Often spelled incorrectly Fukue in English literature.

References

• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Dodson, Aidan & Cant, Serena (2020). Spoils of War: The Fate of Enemy Fleets after Two World Wars. Barnsley, UK: Seaforth Publishing. ISBN 978-1-5267-4198-1.
• Jentschura, Hansgeorg; Jung, Dieter & Mickel, Peter (1977). Warships of the Imperial Japanese Navy, 1869–1945. Annapolis, Maryland: United States Naval Institute. ISBN 0-87021-893-X.

External links

• Combined Fleet: Etorofu