Seaplane and Flying boat
Desperate War of Japan in the Pacific
This page contains kanji.

IJN used seaplanes and flying boats for search of enemy ships and parol in the Pacific War. USN used flying boats for rescue pilots, search enemy ships and patrol.
  1. Pearl Harbor Operation(IJN)
    A Jake of Aichi ejected from IJN heavy cruiser Tone, which informed weather of Pearl Habor before air raid.
  2. K Operation(IJN)
    2 seaplanes flew to Hawaii and bombarded. The 2 seaplane, Emiliy was refueled from 3 submarines at French Frigate Shoals.
  3. Coral Sea Battle
    5 flying boats took off Tulagi on 6th May 1942. One of them spotted TF17 at 0830 but the telegram did not transimt KB. A seaplane flew from the Deboyne Lagoon spotted an enemy oiler but mistook it an aircraft carrier. IJN seaplane tender, Kamikawa-maru supported the search by seaplanes. IJN seaplane tenders had workshops for forging, welding and casting. So they could repair seaplanes and were mini bases for seaplanes. Soon seaplane tenders were not operational because seaplanes could not endure air combats.
    Gunzo, p16-19 No.65
    Flying boat tender, USS Tangier supported 12 PBYs in the Coral Sea Battle.
    Gunzo, p40 No.46
    USS Tangier(AV-8)

  4. Midway Battle
    Heavy cruiser Tone and Chikuma ejected 2 Jakes each, and battle cruiser Haruna also ejected a Type 95 (sea biplane). No.1 Jake of Chikuma flew over the cloud. It was nonsense because IJN seaplanes were not equipped with an airborne radar. No.4 Jake of Tone took off 30min delayed. No.4 had a chart which showed a wrong position of Midway Island.
    USN Midway base took off 22 PBYs at 3am on 4th Jun. One of them spotted a transport convoy. 4 PBY took off at 9:15pm and torpedoed and hit a freighter, Kiyozumi-maru at 3am. All of 4 were equipped with an airborne radar. 11 PBY flew to search KB and one of them spotted the KB at 5:30am on 5th Jun.
    Chihaya, ge p161-162, p166, p171-172

  5. Solomons
    The 958th Kokutai used seaplanes for sweeping PT and submarines.
    958th Kokutai
    PBY always made contacts at night, when IJN destroyers ran slot.

  6. Leyte Battle (IJN)
    IJN battleship Yamato flew an observe sea plane twice in the battle of Leyte. They found other aircraft carriers groups in the south. An flying boat with an airborne radar had found 4 groups of enemy ships at night 0200 before the combat. But the information was reported at 1700. It was too late.Ebina p.312
    IJN mistook commnunication as well as USN did in Solomons. Main heavy cruisers fleet had no seaplanes, because GF(Grand Fleet) ordered to send all of them to land base.

  7. Okinawa Battle (USN)
    VPB squadrons
    USN occupied Kerama Islands at first to get seaplanes base in Mar 1945 just before Okinawa Battle. VPB-208 departed Ulithi Atoll for Kerama Rettoh Okinawa about midnight 31 March 1945. They flew 2,221km azimuth 326°

    The seaplane base move to Chimu Wan. VPBs of the PBMs moved from Kerama near Gushikawa in Jul. The forces was TG50-5 (SEARCH & RECONNAISSANCE GROUP) which had 6 seaplane tenders and 3 destoryers. The seaplane tenders were USS Hamlin(AV-15), St. Geroge(AV-16), Chandeleur (AV-10) and etc.
    Tengan Pier

  8. Japan Mainland Battle(USN)
    USN invaded Kerama Islands at first to get a seaplane base in Okinawa operation of the Pacific War. PBM began to loiter around the west of Kyushu in May 1945. A PBM landed on Kagoshima-wan, and rescued pilot in the after noon of Jun 2nd with fighter air cover.

    PB2M or PB4Y began to flow in the west of Kyushu. These attacked ferries or fishery boats. The sea traffic stopped at the moment. So Sasebo of IJN requested 343rd Koukutai to intercept them. The Kokutai assigned 8 Georges to control the sky till the end of June 1945. Genda p.349

  1. USN Essex class aircraft carrier
    USN developed 46m long of new H-4B hydraulic catapult which could accerate 13t of aircraft at 145km/h(40.2m/s). The catapult worked at 1 rpm. This was not in time the first Essex till Dec 1942. The catapult pulled a F4U loading VAR rockets, 1,000lb bomb and additional fuel tank in the end of the Pacific War. The total weight of the F4U was 3 times of a Zero loading empty!
    Gunzo p85, No76

  2. IJN eye of fleet
    Tone steamming out from Hashirajima to Midway
    IJN used seaplanes for searching the enemy. a E13A1 (Jake) of Aichi ejected from IJN heavy cruiser Tone, scouted Pearl Habor air attack before 30 minutes and informed the weather. Tone class contained 5 or 6 seaplanes. Tone always acted with a kido-butai (fast aircraft carriers strike group) at the battles of Indian Sea, Coral Sea and Midway etc. The photo shows Tone's steamming out from Hashirajima in Japan to Midway. At the Midway battle, The kido-butai launched 7 scouts including 2 torpedo planes from IJN aircraft carrier Akagi and Kaga, Tone and Chikuma ejected 2 Jakes each, battle cruiser Haruna also ejected a Type 95 (sea biplane). The Jake called No.4 from Tone was late a little to eject because the catapult did not work well. No.4 found USN task forces after all. Admiral Nimitz said, 'If the report will be done 30 minutes early, ...' I show specifications of the catapult. I suppose it was developed at the IJN Kure Arsenal.
    Catapult Kure type 25
    • Name : Kure Type 2 model 5
    • Method : gunpower propelled
    • Length : 19.4m(63.8ft)
    • Rail span: 1.2m(3.9ft)
    • Ejecting velocity : 28m/s(31y/s) or 56kt
    • Ejecting weight : 4 ton

  3. USN Escort carrier
    TBF hooking wires
    4 escort carriers ferried aircraft to Okinawa in 1945. Okinawa battle was the last large scale air combat of IJN. USS White Plains (CVE-66) steamed to within 100 miles of the island to launch two squadrons of Marine Corps F4U Corsairs for duty there. USS Hollandia (CVE-97), USS Sitkoh Bay (CVE-86), and USS Breton (CVE-23) enrolled the ferry mission.

    USN had developed hydraulic catapults for years. USN applied them for escort aircraft carriers which ran at max speed 18-20kt, could launch a TBF weighing 8.2 ton at WWII. A site shows beautiful photos of ejecting sea biplanes from USS Colorado etc.

  4. IJN Submarine
    TypeLengthSeaplaneMax loadSubmarine
    Kure Type 1 model 3-Watanabe E9W1-I-7
    Kure Type 1 model 419mYokosuka E14Y1.6tI-8, I-15
    Kure Type 1 model 1026m Aichi M6A5tI-400, I-13, I-14
    IJN was very eager that submarines equip a seaplane. So IJN developed catapults for submarines which were water proof and smaller. But the lenght of the catapults were longer because of weight of new seaplanes. The table shows specifications of catapults for submarines. These catapults were pneumatic.
    Seaplane E9W1

    Kimata, p221, p226, p236, p241
    Yokosuka E14Y
    Aichi M6A
    Watanabe E9W
    96-siki kogata suijyou teisatsuki(E9W1)
    I-7 gata sensuikan

 Submarine and seaboat
Spy Pearl Habor
The War College of IJN had studied air bombardment at Pearl Harbor in 1936, though most of Japanese people believe Yamamoto thought of the idea at first. Reconnaissance was absolutely imperative for IJN. IJN decided to apply submarines and seaplanes for reconnaissance. IJN was to deploy the 6th fleet, submarines at Kwajalein (8.7N, 167.7E), when Japan at the Pacific War. The distance was 3,944km between Kwajalein and Honolulu (21.3N, 157.9W).

 Bombardment of Pearl Harbor ( Operation K )
Frigate Shoals
Frigate Shoals
I-22 had already spied French Frigate Shoals in January 1942.[1][2 So I-15, I-19 and I-26 advanced there to refuel seaplanes, Emily.[5] I-19 guided them by LF radidation. The submarines refueld them. They flew with two 250kg bombs to Honolulu at night, but bombardment were at a loss. I-9 guided 2 Emilies by LF radaiation between French Frigate Shoals and Jaluit Atoll. One Emily returned to Jaluit Atoll.[3] Another returned to Wotje Atoll.[4] I calculate how far 2 Emily flew. 2 Emily moved to Wotje Atoll on 2 March. 3 submarines moved there by early morning on 2 March. Time (JST) line was,[6]

Hawaii islands
4th0025 took off Wotje Atoll
4th1300 flew over French Frigate Shoals
4th1350 took water
4th1600 took off French Frigate Shoals to Hawaii
4th1657 passed Necker Is
4th1825 passed Niihau Is
4th1844 Radar of Kauai Is spotted them
4th1918 US alert, PBY and P-40 took off
4th1935 passed Kauai Is(22N, 159.5W)
4th2100 offshore Oahu Is
4th2110 No1 Emily released four 250kg bombs
4th2130 No2 Emily released four 250kg bombs
5th0910 No2 returend Wotje Atoll
5th0920 No1 returend Jaluit Atoll

2 Emily released bombs after 7 hours at sunset. Emily No.1 flew 3,896km for 12h10min. Emily No.2 flew 3,678km for 11h40min. The cruising speed was 320 and 315km/h each.
Hashimoto, p68

USN dispatched a destroyer at French Frigate Shoals after Emilies refueled there from 3 submarines of I-15, I-19 and I-26 at K operation. Although 6 or 7 IJN submarines refueld seaboats supported, the effect of bombardment was little.

 Indispensable Reefs
Indispensable Reefs position
Rabaul (-4.2, 152.18)1,308km
Gudalcanal (-9.4, 160.0)367km
New Hebrides (-17.8, 168.3)1,021km
I-122 advanced to Indispensable Reefs in mid of September 1942.[7] I-122 refueld seaplanes for a week. I-122 refueld a seaplane on 10 November 1942 there again.

Refuel specifications plan

200x500kg20x250kg &
or 60x250kg
Ration200men/a month1.5t
3 submarines were necessary to refuel 2 Emily in the K operation. IJN had planned refuelling submarines with capacity of aviation gasoline 700kL on Sep 1941. IJNHQ decided to build 2 in October 1943. I-351 launched in January 1945 at last. Ironically I-351 was used to ferry gasoline in Japan mainland. I-351 was not to ferry gasoline in a far atoll to refuel a seaplane.
Gunzo, p20-23, No57
HIJMS Submarine I-351: Tabular Record of Movement

I-366 transported food for soldirs at Pagan Island. I-366 departed from Yokosuka on December 3rd 1944 and stayed at the Tateyama Bay for a few hours till midnight. I-356 ran submerged at 2kt for 20h a day near Saipan 600nm. I-366 arrived at Pagan Island came back on 28 December. I-366 departed for Truk on January 30th 1944 to ferry aircraft parts. I-366 arrived at Truk on February 12. I-366 departed for Woleai Atoll(Mereyon) to ferry food. I-366 came back on 3 March, 1945.
Gunzo, p148-153

 Submarines carried seaplane
E14Y1(Glen) on I-49
IJN had 11 submarines at the Pacific War. They were I-7, I-8 and I-10 for a flag warship. Others were I-15, I-17, I-19, I-21, I-23, I-26. The rest were I-9 and unknown. All of them could load a seaplane called Kingyo(Goldfish), E14Y1 or E9W1. A seaplane of I-7 spied Pearl Harbor on 17th Dec 1941. I-9 spied there on Jan 1942. I think the seaplane of I-7 might be E9W1 because a catapult of I-7 was different from the other submarines.
Yokosuka E14Y

  1. I-10
    1942May10 Durban Habor of South Africa
    1942May30 Diego Suarez Habor of Madagascar
    1942May-- Port Elizabeth of South Africa
    1943Jan23 Noumea
    Kimata, p229
    I-10, Igo 10
  2. I-19
    1942Jan05 Pearl Harbor
    1942May29 Dutch Harbor
    Igo 19
  3. I-25
    I-25 spied ports in the south Pacific as follows in 1942,
    Feb17 Sydney
    Feb26 Melborne
    Mar01 Hobart
    Mar08 Wellington
    Mar12 Oakland
    Mar18 Suva
    Hashimoto, p60-65

  4. I-30
    1942May06 Aden
    1942May08 Djibouti
    Igo 30
  5. I-31
    1942Aug11 ヌデニ島
    1942Aug13 バニコロ飛行偵察
    Igo 31
  6. I-36
    1943Oct17 Pearl Harbor
[1] French Frigate Shoals
[2] French Frigate Shoals Airport (23.86, -166.28)
[3] Jaluit Atoll (6.00, 169.57)
[4] Wotje Atoll(9.44, 170.02)
[6] K sakusen
[7] Indispensable Reefs(-12.67, 160.42)

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