US Navy personnel inspecting the hangar of Japanese submarine I-400, circa late 1945 or early 1946

Caption   US Navy personnel inspecting the hangar of Japanese submarine I-400, circa late 1945 or early 1946 ww2dbase
Source    ww2dbaseUnited States Navy
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I-400   Main article  Photos  
Added By C. Peter Chen
Added Date 20 Aug 2008

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Visitor Submitted Comments

1. Commenter identity confirmed BILL says:
21 Feb 2009 10:14:30 AM

Photo above: Water-tight hatch of hanger tube had a thick two-inch rubber gasket. The hatch could be opened hydraulically or from the outside by turning the rack and spur gear wheel. Ship next to submarine is the sub tender U.S.S. Proteus at dock in Yokosuka, Japan 1945.
2. Commenter identity confirmed Bill says:
3 Feb 2012 02:44:26 PM


The I-400 Class Boats were the largest subs of WWII. They were big,really,really big
400 feet long,5,700tons,range 50,000 miles.
Powered by 4x2,250hp Diesel engines 2x2100hp
Electric motor-generator,Crew about 144 Officers and men.


Armament: 1x25mm Cannon,3x25mm Triple-mount Cannons,1x140mm Main deck gun and 8xTorpedo tubes and 3xAichi M6A1 Seiran Attack aircraft
a forth Aichi M6A1 could also be carried.
The sub had a 120foot long catapult to launch its aircraft, and a special 12 ton crane to recover the Aichi M6A1s


After the I-400 Class Submarines capture the US Navy was faced operating them without any plans or manuals in English, working with the Japanese in sign language,broken English and Japanese crews started to learn how to operate and understand how all the machinery worked every valve and control was tagged and identified. All overhead piping, pumps, electrical conduit and manual and hydraulic equipment were identified and plans were produced for the US Crew to operate the boat.


Equipment,fittings and other machinery were tested or replaced by the Japanese.
The I-400 Class boats followed the standard design for submarine operation. What became
of the Japanese Subs, the three I-400 Class
boats after testing and evaluation, were taken out to sea and used as targets sunk by torpedos. The US destroyed them because the
USSR were demanding access to the subs the US Navy kept what technology that was found secret.
The I-400 Class Boats were the largest subs
operated in WWII, until the nuclear powered
ballistic-missile carrying submarines of the Cold War between the US and USSR.
Did you know the I-400 Submarines hull from the waterline to the keel had a special coating to absorb or diffuse sonar pulses and dampen vibrations of machinery aboard the sub.
Two types of periscopes were German supplied one for daylight the other for night. The Germans also supplies snorkels and other equipment. To some this information may seem historically insignificant,to others a new wealth of information about World War II.


If only one I-400 Class Boat had been kept for posterity for future generations along with the German U-505 Type IXC Boat now on display at the Museum of Science & Industry located in Chicago, Illinois, USA.
I remember my Father taking me to visit the museum and took the tour aboard the German
U-505 at that time, it was outside and exposed to the weather. Since that time, a building has been constructed around the sub to protect it.


By Henry Sakaida
Published by Hikoki Press(2006)
ISBN-10 1902109457
3. Anonymous says:
7 Aug 2015 11:59:04 AM

Seems a loss to history to have just scuttled the one surviving 400 , dam you Cold War you have left a poor legacy.

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