# Kaidai-type submarine

The Kaidai-type submarine (海大型潜水艦, Kaidai-gata sensuikan) was a type of first-class submarine operated by the Imperial Japanese Navy (IJN) before and during World War II. The type name was shortened to Kaigun-shiki Ōgata Sensuikan (海軍式大型潜水艦) Navy Large Type Submarine.
All Kaidai-class submarines originally had a two-digit boat name, from I-51 onwards. On 20 May 1942, all Kaidai submarines added a '1' to their names. For example, I-52 became I-152. Ships are listed by the three-digit boat name if they had one, two-digit if they were not granted one or left service before 20 May 1942.

## Class variants

The Kaidai-type submarines were divided into seven classes and two subclasses:
* Kaidai I (海大1型（伊五十一型）, Kaidai-ichi-gata, I-51-class)
* Kaidai II (海大2型（伊五十二型/伊百五十二型）, Kaidai-ni-gata, I-52/I-152-class)
* Kaidai IIIa (海大3型a（伊五十三型/伊百五十三型）, Kaidai-san-gata-ē, I-53/I-153-class)
* Kaidai IIIb (海大3型b（伊五十六型/伊百五十六型）, Kaidai-san-gata-bī, I-56/I-156-class)
* Kaidai IV (海大4型（伊六十一型/伊百六十二型）, Kaidai-yon-gata, I-61/I-162-class)
* Kaidai V (海大5型（伊六十五型/伊百六十五型）, Kaidai-go-gata, I-65/I-165-class)
* Kaidai VIa (海大6型a（伊六十八型/伊百六十八型）, Kaidai-roku-gata-ē, I-68/I-168-class)
* Kaidai VIb (海大6型b（伊七十四型/伊百七十四型）, Kaidai-roku-gata-bī, I-74/I-174-class)
* Kaidai VII (海大7型（伊七十六型/伊百七十六型）, Kaidai-nana-gata, I-76/I-176-class)

### Kaidai I (I-51 class)

Project number S22. The prototype for the class. The sole Kaidai I, I-51, was based on World War I-era German submarines. She was completed in 1924, refitted with new engines in 1932 and scrapped in 1941. I-51 never saw combat.
* Boat in class
| Boat | Builder | Laid down | Launched | Completed | Fate |
| I-51 (ex-Submarine No. 44) | Kure Naval Arsenal | 6 April 1921 | 29 November 1921 | 20 June 1924 as Submarine No. 44 | Renamed I-51 on 1 November 1924. Decommissioned on 1 April 1940 |

### Kaidai II (I-152 class)

Project number S25. There was only 1 Kaidai II, I-152 planned under the Eight-six fleet together with the I-51. She was completed in 1924, used as a training vessel until mid-1942, then struck from service. She was scrapped in 1946.
* Boat in class
| Boat | Builder | Laid down | Launched | Completed | Fate |
| I-152 (ex-I-52) (ex-Submarine No. 51) | Kure Naval Arsenal | 14 February 1922 as Submarine No. 51 | 12 June 1923 | 20 May 1925 as I-52 | Renamed I-52 on 1 November 1924, decommissioned on 1 August 1942, scrapped post-war |
| Submarine No. 64 | Kure Naval Arsenal | | | | Re-planned as Kaidai IIIa |

### Kaidai IIIa/b (I-153 class and I-156 class)

Project number S26 (Kaidai IIIa) and S27 (Kaidai IIIb). The nine Kaidai IIIs were based on earlier designs, but featured a strengthened hull. The "IIIb" types were 40 cm longer and had a different bow design. All nine boats were constructed between 1927 and 1930.
Of the nine Kaidai IIIs, seven survived the war, as they spent much of their time as training vessels. These were scuttled or scrapped shortly after the end of World War II. I-63 was sunk in a collision with I-60 in 1939, the former losing all her crew. I-63 was refloated and scrapped in 1940. I-60 was later sunk by HMS Jupiter.

### Kaidai IV (I-61/162 class)

Project number S28. Slightly smaller than her predecessors and with only four torpedo tubes, three Kaidai IVs were constructed between 1929 and 1930; I-61, I-162, and I-164. I-61 was lost in a collision in 1941. I-164 was sunk by USS Triton on 17 May 1942. I-162 survived the war.

### Kaidai V (I-165 class)

Project number S29. Three Kaidai Vs were constructed; I-165, I-166, and I-67 which were all completed in 1932. The design saw the upgrade of the deck weapon from a 50 caliber to a 65-caliber long dual-purpose gun. The submarine was also slightly wider and taller, with an increased crew complement of 75 and an increased maximum depth of 230 ft (70 m). I-165 was modified in 1945, her gun removed and two Kaiten manned torpedo suicide attack craft substituted.
None of the Kaidai Vs survived World War II. I-67 was lost with all 87 crew during an exercise in 1940. I-165 was sunk on 27 June 1945, off the east coast of Saipan. I-166 was sunk by the British submarine HMS Telemachus on 17 July 1944, off the coast of Singapore.
| Boat | Builder | Laid down | Launched | Completed | Results | Fate |
| I-165 (ex-I-65) | Kure Naval Arsenal | 19 December 1929 | 2 June 1931 | 1 December 1932 | • Sank Dutch merchant ship Benkoelen on 9 January 1942 • Sank Indian merchant ship Jalarajan on 15 January 1942 • Sank Netherlands merchant Johanne Justesen on 15 February 1942 • Sank RMS Bhima on 20 February 1942 • Sank SS Harmonides on 25 August 1942 • Sank USS Losmar on 24 September 1942 • Sank RMS Perseus on 16 January 1944 • Sank SS Nancy Moller on 18 March 1944 | Converted to a Kaiten mothership in 1945, sunk by USN patrol bomber in the Mariana Islands 15°28′N 153°39′E﻿ / ﻿15.467°N 153.650°E﻿ / 15.467; 153.650 on 27 June 1945 |
| I-166 (ex-I-66) | Sasebo Naval Arsenal | 8 November 1929 | 2 June 1931 | 10 November 1932 | • Sank Dutch submarine HNLMS K XVI on 25 December 1941 • Sank US cargo ship USAT Liberty on 11 January 1942 • Sank Panamanian merchantman Nord 21 January 1942 • Sank RMS Chak Sang on 22 January 1942 • Sank RMS Kamuning 14 February 1942 • Sank Panamanian merchantman Camila on 1 October 1942 • Sank RMS Cranfield on 22 November 1942 | Sunk by HMS Telemachus on 17 July 1944 |
| I-67 | Mitsubishi, Kōbe Shipyard | 8 November 1929 | 2 June 1931 | 10 November 1932 | | Lost in an accident at Minami Torishima on 29 August 1940 |

### Kaidai VIa/b (I-168 class and I-174 class)

Project number S31 (Kaidai VIa) and S34 (Kaidai VIb). They were built in 1931-34 under the 1st Naval Armaments Supplement Programme (Maru 1) and the 2nd Naval Armaments Supplement Programme (Maru 2) for the expansion of the Japanese navy. Constructed between 1934 and 1938, eight Kaidai VIs were built; I-168, I-169, I-70, I-171, I-172, I-73, I-174, and I-175. At 23 knots, this type had the fastest surface speed for any submarine at the time of construction, although the speed was bettered slightly by later Japanese submarines. I-174 and I-175 were of the Kaidai VIb sub-type. They were 30 cm longer, 25 tons heavier, and equipped with a 50 cal deck weapon instead of a 65 cal.
Kaidai VIs contributed to the sinking of two American aircraft carriers during World War II. The destruction of these submarines also hold some milestones; I-70 was Japan's first major warship casualty in World War II, and the sinking of I-73 represented the first warship kill by a United States Navy submarine in the war.
* Boats in classes
| Boat | Sub type | 'Builder | Laid down | Launched | Completed | Results | Fate |
| I-168 (ex-I-68) | Kaidai VIa (Earlier batch) | Kure Naval Arsenal | 18 June 1931 | 26 June 1933 | 31 July 1934 | Sank USS Hammann on 6 June 1942 Sank USS Yorktown on 7 June 1942 | Sunk by USS Scamp at north of Rabaul 27 July 1943 |
| I-169 (ex-I-69) | Kaidai VIa (Earlier batch) | Mitsubishi, Kōbe Shipyard | 22 December 1932 | 15 February 1934 | 28 September 1935 | Sank Dutch merchantman Tjinegara 21 July 1942 | Sunk by air raid at Truk on 4 April 1944 |
| I-70 | Kaidai VIa (Earlier batch) | Sasebo Naval Arsenal | 25 January 1933 | 14 June 1934 | 9 November 1935 | | Sunk by aircraft from USS Enterprise in the Hawaiian Islands on 10 December 1941 |
| I-171 (ex-I-71) | Kaidai VIa (Latter batch) | Kawasaki, Kōbe Shipyard | 15 February 1933 | 25 August 1934 | 24 December 1935 | Sank USS General Royal T. Frank on 19 January 1942 | Sunk by USS Guest and USS Hudson west of Buka Island on 30 January 1944 |
| I-172 (ex-I-72) | Kaidai VIa (Latter batch) | Mitsubishi, Kōbe Shipyard | 16 December 1933 | 6 April 1935 | 7 January 1937 | Sank USS Prusa on 19 December 1941 Sank the oiler USS Neches on 23 January 1942 | Sunk by USS Southard at San Cristobal 10 November 1942 |
| I-73 | Kaidai VIa (Latter batch) | Kawasaki, Kōbe Shipyard | 5 September 1933 | 20 June 1935 | 7 January 1937 | | (1). Sunk by USS Gudgeon at Midway Atoll 28°24′N 178°35′E﻿ / ﻿28.400°N 178.583°E﻿ / 28.400; 178.583 on 27 January 1942 |
| I-174 (ex-I-74) | Kaidai VIb | Sasebo Naval Arsenal | 16 October 1934 | 28 March 1937 | 15 August 1938 | Sank US Army transport Portmar on 16 June 1943 and damaged USS LST-469 in an attack on Convoy GP55 on 16 June 1943 | Sunk by a United States Navy B-24 Liberator patrol aircraft near Truk on 12 April 1944 |
| I-175 (ex-I-75) | Kaidai VIb | Mitsubishi, Kōbe Shipyard | 1 November 1934 | 16 September 1936 | 18 December 1938 | Sank USS Manini 18 December 1941 Damaged Australian merchant ship Allara on 23 July 1942 Sank Australian merchant ship Murada on 24 July 1942 Sank French merchant vessel Cagou on 28 July 1942 Sank RMS Dranker on 3 August 1942 Sank USS Liscome Bay on 24 November 1943 | Sunk by USS Nicholas northeast of Wotje Atoll on 17 February 1944 |

### Kaidai VII (I-176 class)

Project number S41. The final design in the Kaidai class, ten Kaidai VIIs were ordered in 1939 (I-176 I-185), and were completed over the course of 1942 and 1943. They were built in 1939 under the Maru 4 Programme. The IJN called New Kaidai (新海大型, Shin Kaidai-gata) unofficially, and intended to replace this type with Kaidai III and Kaidai IV. Instead of possessing some aft-firing torpedo tubes as all other predecessors did, the Kaidai VII's six tubes all faced forward. They had an endurance of 75 days.
Seven of the ten Kaidai VIIs were sunk within their first year of operation and all ten vessels were sunk by October 1944.
* Boats in class
| Boat No. | Boat | Builder | Laid down | Launched | Completed | Results | Fate |
| 154 | I-176 (ex-I-76) | Kure Naval Arsenal | 22 June 1940 as I-76 | 7 June 1941 | 4 August 1942 as I-176 | Damaged USS Chester on 20 October 1942 Sank USS Corvina on 17 November 1943 | Sunk by USS Franks and USS Haggard northwest of Buka Island on 17 May 1944. |
| 155 | I-177 (ex-I-77) | Kawasaki, Kōbe Shipyard | 10 March 1941 as I-77 | 20 December 1941 | 28 December 1942 as I-177 | Sank RMS Limerick on 26 April 1943 Sank AHS Centaur on 14 May 1943 | Sunk by USS Steele and USS Samuel S. Miles northwest of Palau on 3 October 1944 |
| 156 | I-178 (ex-I-78) | Mitsubishi, Kōbe Shipyard | 21 May 1941 as I-78 | 24 February 1942 | 26 December 1942 as I-178 | Sank Liberty ship Lydia M. Child on 27 April 1943 | Lost sometime after 17 June 1943 during a patrol off eastern Australia. Cause of loss not known, but some sources attribute it to Royal Australian Air Force aircraft. |
| 157 | I-179 (ex-I-79) | Kawasaki, Kōbe Shipyard | 21 August 1941 as I-79 | 16 July 1942 as I-179 | 8 June 1943 | | Lost in an accident at Iyo Nada on 9 July 1943 |
| 158 | I-180 (ex-I-80) | Yokosuka Naval Arsenal | 17 April 1941 as I-80 | 7 February 1942 as I-180 | 15 January 1943 | Sank Australian merchant ship Wollongbar on 29 April 1943 Sank Norwegian merchant ship SS Fingal 5 May 1943 Damaged Australian merchant vessel Ormiston on 12 May 1943 Damaged Australian merchantman Caradale on 12 May 1943 | Sunk by USS Gilmore at Dutch Harbor 55°10′N 155°40′W﻿ / ﻿55.167°N 155.667°W﻿ / 55.167; -155.667 on 27 April 1944 |
| 159 | I-181 | Kure Naval Arsenal | 11 November 1941 | 2 May 1942 | 25 May 1943 | | Sunk by USN destroyer and patrol torpedo boat in New Guinea on 16 January 1944 |
| 160 | I-182 | Yokosuka Naval Arsenal | 10 November 1941 | 20 May 1942 | 10 May 1943 | | (1). Sunk by USS Wadsworth at Espiritu Santo on 1 September 1943 |
| 161 | I-183 | Kawasaki, Kōbe Shipyard | 26 December 1941 | 21 January 1943 | 3 October 1943 | | Sunk by USS Pogy south of Shikoku on 28 April 1944 |
| 162 | I-184 | Yokosuka Naval Arsenal | 1 April 1942 | 12 December 1942 | 15 October 1943 | | Sunk by aircraft from USS Suwannee southeast of Saipan on 19 June 1944 |
| 163 | I-185 | Yokosuka Naval Arsenal | 9 February 1942 | 16 September 1942 | 23 September 1943 | | Sunk by USS Newcomb and USS Chandler northwest of Saipan on 22 June 1944 |

## Characteristics

| Type | Type | 'Kaidai I (I-51) | 'Kaidai II (I-152) | Kaidai IIIa (I-153) | Kaidai IIIb(I-156) | Kaidai IV (I-61) |
| Displacement | Surfaced | 1,390 long tons (1,412 t) | 1,390 long tons (1,412 t) | 1,635 long tons (1,661 t) | 1,635 long tons (1,661 t) | 1,575 long tons (1,600 t) |
| Displacement | Submerged | 2,430 long tons (2,469 t) | 2,500 long tons (2,540 t) | 2,300 long tons (2,337 t) | 2,300 long tons (2,337 t) | 2,300 long tons (2,337 t) |
| Length (overall) | Length (overall) | 91.44 m (300 ft 0 in) | 100.85 m (330 ft 10 in) | 100.58 m (330 ft 0 in) | 101.00 m (331 ft 4 in) | 97.70 m (320 ft 6 in) |
| Beam | Beam | 8.81 m (28 ft 11 in) | 7.64 m (25 ft 1 in) | 7.98 m (26 ft 2 in) | 7.90 m (25 ft 11 in) | 7.80 m (25 ft 7 in) |
| Draft | Draft | 4.60 m (15 ft 1 in) | 5.14 m (16 ft 10 in) | 4.83 m (15 ft 10 in) | 4.90 m (16 ft 1 in) | 4.83 m (15 ft 10 in) |
| Depth | Depth | 6.02 m (19 ft 9 in) | 6.71 m (22 ft 0 in) | 6.71 m (22 ft 0 in) | 6.70 m (22 ft 0 in) | 6.70 m (22 ft 0 in) |
| Propulsion | Propulsion | 4 × Sulzer Mk.2 diesels 4 shafts | 2 × Sulzer Mk 3 diesels 2 shafts | 2 × Sulzer Mk 3 diesels 2 shafts | 2 × Sulzer Mk 3 diesels 2 shafts | 2 × Rauschenbach Mk 2 diesels 2 shafts |
| Power | Surfaced | 5,200 bhp | 6,800 bhp | 6,800 bhp | 6,800 bhp | 6,000 bhp |
| Power | Submerged | 2,000 shp | 1,800 shp | 1,800 shp | 1,800 shp | 1,800 shp |
| Speed | Surfaced | 18.4 knots (34.1 km/h) | 20.1 knots (37.2 km/h) | 20.0 knots (37.0 km/h) | 20.0 knots (37.0 km/h) | 20.0 knots (37.0 km/h) |
| Speed | Submerged | 8.4 knots (15.6 km/h) | 7.7 knots (14.3 km/h) | 8.0 knots (14.8 km/h) | 8.0 knots (14.8 km/h) | 8.5 knots (15.7 km/h) |
| Range | Surfaced | 20,000 nmi (37,000 km) at 10 knots (19 km/h) | 10,000 nmi (19,000 km) at 10 knots (19 km/h) | 10,000 nmi (19,000 km) at 10 knots (19 km/h) | 10,000 nmi (19,000 km) at 10 knots (19 km/h) | 10,000 nmi (19,000 km) at 10 knots (19 km/h) |
| Range | Submerged | 100 nmi (190 km) at 4 knots (7.4 km/h) | 100 nmi (190 km) at 4 knots (7.4 km/h) | 90 nmi (170 km) at 3 knots (5.6 km/h) | 60 nmi (110 km) at 3 knots (5.6 km/h) | 60 nmi (110 km) at 3 knots (5.6 km/h) |
| Test depth | Test depth | 45.7 m (150 ft) | 45.7 m (150 ft) | 60.0 m (196.9 ft) | 60.0 m (196.9 ft) | 60.0 m (196.9 ft) |
| Fuel | Fuel | 508 tons | 284.5 tons | 241.8 tons | 230 tons | 230 tons |
| Complement | Complement | 70 | 58 | 63 | 63 | 58 |
| Armament (initial) | Armament (initial) | • 8 × 533 mm (21 in) TTs (6 × bow, 2 × aft) • 24 × 6th Year Type torpedoes • 1 × 120 mm (4.7 in) L/45 3rd Year Type Naval gun | • 8 × 533 mm (21 in) TTs (6 × bow, 2 × aft) • 16 × 6th Year Type torpedoes • 1 × 120 mm (4.7 in) L/45 3rd Year Type Naval gun • 1 × 76.2 mm (3.00 in) L/23.5 AA gun | • 8 × 533 mm (21 in) TTs (6 × bow, 2 × aft) • 16 × 6th Year Type torpedoes • 1 × 120 mm (4.7 in) L/40 11th Year Type Naval gun • 1 × 7.7 mm MG | same as Kaidai IIIa | • 6 × 533 mm (21 in) TTs (4 × bow, 2 × aft) • 14 × Type 89 torpedoes • 1 × 120 mm (4.7 in) L/40 11th Year Type Naval gun • 1 × 7.7 mm MG |
| Type | Type | Kaidai V (I-165) | Kaidai VIa (Earlier batch, I-168) | Kaidai VIa (Latter batch, I-171) | Kaidai VIb (I-174) |
| Displacement | Surfaced | 1,575 long tons (1,600 t) | 1,400 long tons (1,422 t) | same as Earlier batch | 1,420 long tons (1,443 t) |
| Displacement | Submerged | 2,330 long tons (2,367 t) | 2,440 long tons (2,479 t) | same as Earlier batch | 2,564 long tons (2,605 t) |
| Length (overall) | Length (overall) | 97.70 m (320 ft 6 in) | 104.70 m (343 ft 6 in) | same as Earlier batch | 105.00 m (344 ft 6 in) |
| Beam | Beam | 8.20 m (26 ft 11 in) | 8.20 m (26 ft 11 in) | same as Earlier batch | 8.20 m (26 ft 11 in) |
| Draft | Draft | 4.70 m (15 ft 5 in) | 4.58 m (15 ft 0 in) | same as Earlier batch | 4.60 m (15 ft 1 in) |
| Depth | Depth | 7.05 m (23 ft 2 in) | 7.00 m (23 ft 0 in) | same as Earlier batch | 7.00 m (23 ft 0 in) |
| Power plant and shaft | Power plant and shaft | 2 × Sulzer Mk.3 diesels 2 shafts | 2 × Kampon Mk.1A Model 8 diesels, 2 shafts | same as Earlier batch | 2 × Kampon Mk 1A Model 8 diesels, 2 shafts |
| Power | Surfaced | 6,000 bhp | 9,000 bhp | same as Earlier batch | 9,000 bhp |
| Power | Submerged | 1,800 shp | 1,800 shp | same as Earlier batch | 1,800 shp |
| Speed | Surfaced | 20.5 knots (38.0 km/h) | 23.0 knots (42.6 km/h) | same as Earlier batch | 23.0 knots (42.6 km/h) |
| Speed | Submerged | 8.2 knots (15.2 km/h) | 8.2 knots (15.2 km/h) | same as Earlier batch | 8.2 knots (15.2 km/h) |
| Range | Surfaced | 10,000 nmi (19,000 km) at 10 knots (19 km/h) | 14,000 nmi (26,000 km) at 10 knots (19 km/h) | same as Earlier batch | 10,000 nmi (19,000 km) at 16 knots (30 km/h) |
| Range | Submerged | 60 nmi (110 km) at 3 knots (5.6 km/h) | 65 nmi (120 km) at 3 knots (5.6 km/h) | same as Earlier batch | 90 nmi (170 km) at 3 knots (5.6 km/h) |
| Test depth | Test depth | 75.0 m (246.1 ft) | 70.0 m (229.7 ft) | same as Earlier batch | 85.0 m (278.9 ft) |
| Fuel | Fuel | 230 tons | 341 tons | same as Earlier batch | 442 tons |
| Complement | Complement | 62 | 68 | same as Earlier batch | 68 |
| Armament(initial) | Armament(initial) | • 6 × 533 mm (21 in) TTs (4 × bow, 2 × aft) • 14 × Type 89 torpedoes • 1 × 100 mm (3.9 in) L/50 Type 88 AA gun • 1 × 12.7 mm AA gun • 1 × 7.7 mm MG | • 6 × 533 mm (21 in) TTs (4 × bow, 2 × aft) • 14 × Type 89 torpedoes • 1 × 100 mm (3.9 in) L/50 Type 88 AA gun • 1 × 13.2 mm (0.52 in) AA gun • 1 × 7.7 mm MG | • 6 × 533 mm (21 in) TTs (4 × bow, 2 × aft) • 14 × Type 89 torpedoes • 1 × 120 mm (4.7 in) L/40 11th Year Type Naval gun • 1 × 13.2 mm AA gun • 1 × 7.7 mm MG | • 6 × 533 mm (21 in) TTs (4 × bow, 2 × aft) • 14 × Type 89 torpedoes • 1 × 120 mm (4.7 in) L/40 11th Year Type Naval gun • 1 × 13.2 mm AA gun |

## Footnotes

* ↑ The 海大 read as Kai-Dai, but the 大型 read as Ō-gata in Japanese.
* ↑ "Type KD1". Combinedfleet.com – Imperial Japanese Navy Page. Retrieved 20 February 2007.
* ↑ 伊号第51潜水艦 (I-Gō Dai-51 Sensuikan). The same shall apply hereinafter.
* 1 2 "Type KD3". Combinedfleet.com – Imperial Japanese Navy Page. Retrieved 20 February 2007.
* ↑ HMS JUPITER (G 85) – J-class Destroyer
* ↑ "Type KD4", Imperial Japanese Navy Page, Combinedfleet.com, retrieved 20 February 2007
* 1 2 "Type KD5". Imperial Japanese Navy Page. Combinedfleet.com. Retrieved 20 February 2007.
* 1 2 "Type KD6". Imperial Japanese Navy Page. Combinedfleet.com. Retrieved 20 February 2007.
* ↑ Bob Hackett; Sander Kingsepp (2001). "IJN Submarine I-73: Tabular Record of Movement". Combined Fleet. Retrieved 13 February 2012.
* 1 2 Smith (1992) pg. 29
* 1 2 3 "Type KD7". Combinedfleet.com – Imperial Japanese Navy Page. Retrieved 20 February 2007.
* ↑ Hackett, Bob; Kingsepp, Sander (2001). "IJN Submarine I-178: Tabular Record of Movement". combinedfleet.com. Retrieved 29 December 2012.