FUKURYU Japanese navy divers

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genkideskan
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Joined: 07 Feb 2007, 00:28
Location: Germany

FUKURYU Japanese navy divers

#1

Post by genkideskan » 05 May 2008, 23:15

A less known unit of the Imperial Japanese Navy was the Special Harbor Defense and Underwater Attack Unit - Tokyo Bay.

-- FUKURYU --

These divers used rubber diving suites with a circular breath system. The air contains only 23 % oxigen and this spent oxigen was replaced by two steel 3,5 liter compressed oxigen bottles by a valve/pressure device. The poisonous CO² we breath out was bound by a Calciumoxid purifier cartridge. There are no bubbles or wakes visible at the surface.
These system was known from U Boat safe and breath devices. 1000 suits where completed. 10000 more was ordered. The system was simple and effective and several suits where shipped to the USA for closer tests and examination.

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This suite enabled trained divers to be submerged for 8 hours in about 8 meter deep water. For a longer time the oxigen breathing become poisonous for the body in more than 10 meter deep water. It was no problem to walk about 2000 meter in a hour. A liquid food was developed and the diver could eat underwater with a small hose.
Shortly for trained persons 35 meter where possible and the suite improved every day. At the end of the war 4000 men served in the unit, 1200 men where well trained. Every man got a wrist compass and a flashlight.

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The weapon was a sort of lance mine - the Type 5 attack mine. It was
3,3 meter long with a 56 cm long sheet metal container holding a 10 Kg TNT charge. The rest of the container was empty and used as a floating chamber.
Ignited by a 12cm long horn fuze very similar to, if not the fuze used on sea mines.

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The diver simply push the mine against a ship. The tested safety range between each diver was app. 60 meter.
Submerged concrete installations and sunken ships with a diver chamber shouldt be bases for several divers equipped with food, water and oxigen bottles.

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Normal mines and underwater explosives should be used too. Even underwater torpedo facilities where build. May be they are still there today.
This is a memorial statue in a japanese museum

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Any additional information about this subject is very welcome!!!

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genkideskan
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Posts: 26
Joined: 07 Feb 2007, 00:28
Location: Germany

Re: FUKURYU Japanese navy divers

#3

Post by genkideskan » 06 May 2008, 14:07

Thanks a lot for the link Taki.

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ShindenKai
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Re: FUKURYU Japanese navy divers

#4

Post by ShindenKai » 07 Jul 2023, 21:18

According to the US Navy Technical Mission to Japan
https://www.fischer-tropsch.org/primary ... 200-24.pdf

-A complete Fukuryu diving suit was sent to Ordnance Investigation Laboratory, Indianhead, Maryland (enclosure "F")

-10,000 Type 5 mines had been ordered, NONE were completed by wars end.
**400 dummy/practice mines were used for training, 20 of which were rigged to show the diver he'd made contact**

-The Fukuryu were also supposed to release floating sea-mines anchored to ocean floor, before using their Type 5's

-Platoon leaders were supposed to use special periscopes...no further explanation/info.

-Plans were to construct underwater reinforced concrete enclosures holding 6-18 men, in a variety of shapes (built ashore, with the exterior made to look like uneven/irregular rocks) and sunk at depths no greater than 15m (50ft). They were to be equip'd w/a transfer compartment and living quarters.
-One purposed plan was to use inoperative cargo vessels/ships
-Underwater "foxholes" were tested: sections of large concrete pipe with steel doors. Tests with dogs showed that they were quite effective at reducing effects of underwater explosions.

-Each diver was given an ensign to wear: placing him in the same category as combatant ship.

-Divers could stay underwater in their suits for 8hrs continuously.

-15m depth max, plans to increase to 35m (115ft)
Attachments
Fukuryu Diving Suit Front.jpg
Fukuryu Diving Suit Back.jpg
Fukuryu Diving Suit.jpg
Fukuryu Type 5 Attack Mine.jpg
USNTMJ Underwater Torp Battery on sunken ship.jpg

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