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No.1-class patrol boat (1940)
Class overview
Name: No.1-class patrol boat
Builders: Yokosuka Naval Arsenal
Operators: Naval Ensign of Japan Imperial Japanese Navy
Succeeded by: Matsu-class destroyer
No.1-class landing ship
Built: 1940
In commission: 1940 – 1945
Planned: 4
Completed: 2
Cancelled: 2 (replaced to 4 × No.31-class)
Lost: 2
General characteristics
Type: Patrol boat
Displacement: 1,270 long tons (1,290 t) standard
Length: April 1940
102.57 m (336 ft 6 in) overall
Beam: 8.92 m (29 ft 3 in)
Propulsion: 2 × Mitsubishi-Parsons geared turbines
2 × Kampon water tube boilers
2 shafts, 10,000 shp
Speed: 22.0 knots (25.3 mph; 40.7 km/h)
Armament: April 1940
• 3 × 120 mm (4.7 in) L/45 naval guns
• 2 × 533 mm (21.0 in) torpedo tubes
• 2 × 533 mm torpedoes
Late 1941
• 2 × 120 mm (4.7 in) L/45 naval guns
• 4 × Type 96 25 mm AA guns
• 2 × depth charge throwers
• 18 × depth charges
• 2 × landing crafts and 250 troops,
or 42 × depth charges

The No. 1 class patrol boat (第一号型哨戒艇, Dai Ichi Gō-gata Shōkaitei?) was a class of patrol boats of the Imperial Japanese Navy (IJN), serving during World War II. 2 vessels were converted from Minekaze-class destroyers in 1940.


  • In 1939, the IJN was liberated from London Naval Treaty, and they built a lot of Kagerō-class destroyers. On the other hand, aging of the Minekaze-class destroyers were serious. Their boilers were worn down very much because they were destroyers. Some Minekaze-class were not able to show 30 knots speed. The Navy General Staff made the Confidential Document No.456. It was an order to rebuilt them into patrol boat about four of Minekaze-class destroyers and six of Momi-class destroyers. The IJN chose Shimakaze and Nadakaze among Minekaze-class.


  • Shimakaze and Nadakaze were sent to Yokosuka Naval Arsenal for rebuilt. B turret, four torpedo tubes, and two boilers were removed in 1940. In this point in time, they left a feature of the destroyer.
  • Second half of 1941, the IJN rebuilt them once again for war preparations.[1] They were rebuilt to the landing craft carrier. They were removed Y turret and torpedo tubes, and enclosed well deck. Furthermore, slope for Daihatsu was installed to their stern. Well-deck ruins were able to accommodate 250 troops (for two companies of Navy Landing Force).


  • 8 December 1941: Sortie for invasion of Batanes Islands. (No.1 and No.2)
  • 24 December 1941: Sortie for invasion of Lamon Bay. (No.1 and No.2)
  • 11 January 1942: Sortie for Battle of Manado. (No.1, No.2 and No.34)
  • 12 February 1942: Sortie for invasion of Makassar. (No.1 and No.2)
  • 20 February 1942: Sortie for invasion of Kupang. (No.1, No.2 and No.39)
  • (after): The IJN which finished First Phase Operations allotted them to the convoy escort operations. And No.1 and No.2 were sunk by Allied submarines.

Ships in classEdit

Ship Completed as destroyer Rebuilt completed Fate
Patrol boat No. 1 [2]
15 November 1920 First quarter of 1940 at Yokosuka Naval Arsenal.
Renamed Patrol boat No. 1 on 1 April 1940.[3]
Sunk by USS Guardfish at west off Kavieng 02°51′S 149°43′E / 2.85°S 149.717°E / -2.85; 149.717 on 12 January 1943. Decommissioned on 10 February 1943.
Patrol boat No. 2
30 September 1921 First quarter of 1940 at Yokosuka Naval Arsenal.
Renamed Patrol boat No. 2 on 1 April 1940.[3]
Sunk by HMS Stubborn at Lombok Strait 07°07′S 115°40′E / 7.117°S 115.667°E / -7.117; 115.667 on 25 July 1945. Decommissioned on 30 September 1945.

See alsoEdit


  1. About the time of their entering a dock, correct historical materials were not left.
  2. 第一号哨戒艇 (Dai 1 Gō Shōkaitei?). The same shall apply hereinafter.
  3. 3.0 3.1 1 April 1940, Notice No. 72, Reclassified old destroyers to auxiliary boat. (昭和十五年四月一日 海軍大臣官房達第七十二号 舊驅逐艦ヲ特務艇籍ニ編入シ左ノ通命名ス 海軍大臣 吉田善吾), Minister's Secretariat, Ministry of the Navy.


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