Submarine and seaboat
Desperate War of Japan in the Pacific
This page contains kanji.
 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

    1942May10 Durban Habor of South Africa
    1942May30 Diego Suarez Habor of Madagascar
    1942May-- Port Elizabeth of South Africa
    1943Jan23 Noumea
    Kimata, p229
    Igo 10

    1942Jan05 Pearl Harbor
    1942May29 Dutch Harbor
    Igo 19

    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

    1942May06 Aden
    1942May08 Djibouti
    Igo 30

    1942Aug11 ヌデニ島
    1942Aug13 バニコロ飛行偵察
    Igo 31

    1943Oct17 Pearl Harbor
    Igo 36

[1] French Frigate Shoals
[2] French Frigate Shoals Airport (23.86, -166.28)
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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