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November 15, 2009

Rediscovered: WWII Japanese submarine aircraft carrier

The I-14, a World War II Japanese submarine aircraft carrier has been discovered off the coast of Oahu, along with the I-201, one of the fastest submarines of World War II.

They were deliberately sunk by the U.S. Navy in 1946 to prevent their technology falling into Soviet hands. They were originally intended for an attack on the U.S. mainland including New York City and Washington D.C. and had capabilities unmatched until the arrival of nuclear submarines.

The discovery was made by the National Oceanic and Atmospheric Administration's (NOAA's) Undersea Research Lab at the University of Hawaii at Manoa and by National Geographic Channel (NGC), which documented and partly funded the search mission for the upcoming special Hunt for the Samurai Subs, premiering Tuesday, November 17, at 9:00 p.m. ET/PT during the network's second annual Expedition Week.

"This is one of the more significant marine heritage findings in recent years," said Dr. Hans Van Tilburg, of NOAA's Office of National Marine Sanctuaries, who called the subs "60-year-old time capsules offering firsthand insight into a military technology that was far ahead of its time --so much so that if introduced earlier and in greater numbers, the submarines had the potential to turn the tide of war."

Since 1992, a team led by Terry Kerby, HURL operations director and chief pilot, has used the manned submersibles Pisces IV and Pisces V during test and trial dives to hunt for the submarines and other lost maritime heritage artifacts. In March 2005, the I-401, which carried three aircraft, was the first submarine located. Its discovery was publicly announced that same year. The I-400, sister ship to the I-401, remains undiscovered. The I-14 and the I-201 attack submarines -- which were both capable of staying submerged for up to a month -- were discovered in February 2009, with the official public announcement being made last week.

16mm film footage, taken by the U.S. Navy in 1946 of the I-14 submarine as she was sunk, revealed a target area the team had never explored before. At a depth of almost 3,000 feet, the two newly discovered subs were identified by signs of a catapult launch ramp on the forward deck leading to the bow and the ship's numbers painted on the conning tower.

Japan's aircraft-carrying submarines held up to three folding-wing float plane bombers that could be launched by catapult just minutes after surfacing. Each aircraft could carry a powerful 1,800-pound bomb to attack the U.S. mainland. Though the targets later shifted, none of the missions were carried out.

At 400 feet, the I-400 "Sen-Toku" class were the largest submarines ever built until the introduction of nuclear-powered submarines in the 1950s. With a range of 37,500 miles, they were able to go one and a half times around the globe without refueling, a capability yet to be matched by any other diesel-electric submarine.

At the end of WWII, the U.S. Navy captured the subs and had exclusive access to their technology. When the Soviet Union demanded access in 1946 under the terms of the treaty that ended the war, the U.S. Navy sunk the subs off the coast of Oahu and claimed to have no information on their precise location.

The wreckage of the submarines will be seen for the first time in high definition in Hunt for the Samurai Subs. The film includes the WWII-era 16mm film footage shot by Charles Alger, a retired U.S. Navy chief in charge of the 1-14. In an interview, Alger says of the sinking, "It was very sickening, the moment of the explosion. But like any good sailor, a job is done, and we've done it ... I never ever thought that it would ever be seen by a human being again." Retired U.S. Navy commander Buck Catlin explains the rationale behind it: "It was decided to take those submarines out to sea off of Pearl Harbor, one at a time, and fire torpedoes and sink them. One of the main objects was to keep them away from the Russians, so we kept it quiet. And that's one of the reasons why the Submarine Force never advertised what we're talking about today."

Other key interviews in the film include Atsushi Asamura, a kamikaze pilot assigned to the I-401 aircraft-carrying submarine; Van Tilburg, who also surveyed the underwater wreckage; and Dik Daso, curator of modern military aircraft at the Smithsonian's National Air and Space Museum, which houses the sole surviving Aichi M6A1 Seiran plane built for the Japanese subs.

TOM PAINE'S JOURNAL

Go to http://www.pacerfarm.org/i-400/ for an incredibly detailed memoir on the I-401 by the late Tom Paine that begins:

"This saga recounts my adventures during the last voyage of His Imperial Japanese Majesty's Sensuikan Toku (Special Submarines). In 1945 I returned from World War II as Executive Officer and Navigator of the U.S. Navy prize crew in one of these aircraft-carrying giants: H.I.J.M.S. I-400. Sailing her from Sasebo, Occupied Japan, to Pearl Harbor, Territory of Hawaii, seemed a fitting finale to my career in the Submarine Service.

"I'll begin by describing Japan's Top Secret submersible aircraft carriers, summarize their operational history, recount my experience in the Occupation of Japan, explain how our prize crew learned to operate the unusual I-boats, and tell the tale of I-400's eventful transpacific passage

"In many ways H.I.J.M.S. I-400 was decades ahead of her time. She was the world's largest submarine, with a length of 400 feet and a surfaced displacement of 3,530 tons. Above her main deck rose a 115 foot long, 12 foot diameter, hangar housing three torpedo-bombers. These floatplanes were rolled out through a massive hydraulic door onto an 85 foot pneumatic catapult, where they were rigged for flight, fueled, armed, launched, and, after landing alongside, lifted back aboard with a powerful hydraulic crane. The I-400 was equipped with a snorkel, radar, radar detectors, and capacious fuel tanks that gave her a range of 37,500 miles: one and a half times around the world. She was armed with eight torpedo tubes, a 5.5 inch 50 caliber deck gun, a bridge 25mm antiaircraft gun, and three triple 25mm A/A mounts atop her hangar. The advent of guided missiles and atomic bombs transformed her from an overspecialized undersea dinosaur to a menacing strategic threat. Like Germany's Type XXI U-boat she was too late to influence World War I...


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