The I-BOAT BUCCANEERS

At Times More Reminiscent of Spoofs Like McHale's

Navy or Mr. Roberts Than a True US Navy Adventure

FOREWORD: At the end of World War II, three huge Japanese submarines were turned over, albeit reluctantly, by their defeated and dispirited crews to the United States Navy. The trio’s mere presence, not to mention their size and unique capabilities, came as a shock to the Americans. Two of the ‘big boats’…the un-named I-400 and I-401, were moved to Hawaii for inspection by what were formally called ‘prize crews’, which consisted of American submariners. Calling themselves the ‘I-Boat Buccaneers’, their memorable trip in late 1945 was made under power, but only on the surface. Their log books and later recollections, even after discounting the ever-expansive nature of sea stories prone to multiple retellings, constitute one of the more unusual voyages ever made by any navy. It was a saga of the seas like no other. Their adventures, including preparations made before departing and at island stops along the way were downright comical at times. We have the Executive Officer and Navigator of I-400’s prize crew, veteran American submariner Lieutenant Thomas O. Paine to thank for preserving the story of the I-Boat Buccaneers’ eventful trans-Pacific passage. What follows is based largely on his recorded recollections, and includes numerous direct quotes from that source. After all, it is his story. Late in life, Lieutenant Paine augmented his memories and those of other prize crew members by extracting extensive data, dates and details from Navy records. The result of his years’ long effort was published in 1991.

Bill Lee

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I-400 SEN TOKU I-400 Class Design: In many ways, the Japanese Navy’s I-400 Class of submarines, developed in the midst of wartime, were years ahead of their time. They were bigger than any other submarines in commission, or even on any nation’s drawing boards, at the time.

The Sen Toku (Japanese for special type submarine) design was 400 feet long and displaced 6,560 tons, submerged. By contrast, the US Navy’s Fleet-type class of submarine, which was so successful during World War II, measured 311 feet long and displaced 2,463 tons submerged. The I-400 Class design featured a 115 foot long, twelve foot clear inside diameter hangar, capable of housing up to three float planes, with their flying surfaces folded, much like some kind of giant, mechanical Origami. Their launching platform was an 85 foot long pneumatic catapult. Each sub was fitted with a twelve-ton hydraulic crane for lifting aircraft back onboard following a sea landing. Each of these submersibles was armed with eight torpedo tubes, a 5.5 inch deck gun and several antiaircraft weapons. Other features included a primitive snorkel, degaussing equipment, advanced sonar, radar and radar detecting gear. The crew of each I-400 Class boat consisted of 114 officers and enlisted men. Capacious fuel tanks gave these subs a range of 37,500 miles; equal to one and a half times the world’s circumference. Four diesel engines, producing a total of 4,500 shaft horsepower could propel these beasts at 18.7 knots on the surface. Two electric motors, with a combined output of 4,200 shaft horsepower could drive them, submerged at 12 knots. The cross-section of their hulls amidships resembled the figure eight, separated in the middle by a vertical watertight bulkhead that ran fore and aft along each sub’s centerline.

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Their conning towers were offset seven feet to port in order to help make room for the huge hangars. The hangars were offset two feet to starboard of centerline, in part to help balance the boats. These features were very disconcerting to American submariners who came into contact with the I-400 Class, since they were accustomed to almost every major feature of any submarine being oriented on the centerline. Another innovation, copied from German U-boat advanced designs, was a rubberized anti-radar coating which was applied to the Japanese subs' conning towers to make detection while on the surface difficult. In addition, an anechoic coating made of gum, asbestos and adhesives was applied to the submarines’ hulls, which was intended to absorb or diffuse enemy sonar pulses and make detection while submerged more difficult. Several compartments within the submarines’ hulls were devoted to aircraft maintenance and the storage of high octane fuel and aerial torpedoes. A small number of the men who went to sea in these submarines were not submariners at all, but aircraft mechanics and pilots. For a nation long ridiculed as being unimaginative copy-cats, the many features of the I-400 Class, conceived and created in the midst of wartime, certainly dispelled that notion. But all of these features were overwhelmed by the massive watertight hatch fitted to the forward end of the airplane hangar. Its size can best be appreciated when contrasted with the American sailor in the image to the right. Originally, eighteen units of the I-400 Class of subs were contemplated. But just five of these massive Japanese submersible warships were laid down, and only three were eventually completed. One of them, the I-402 was completed very late in the war and never became a commissioned unit of the Imperial Japanese Navy. The other two, I-400 and I-401 were completed in December 1944, and January 1945, respectively. Their operational history was less than noteworthy. In wartime service for only a few months before Japan surrendered, neither the I-400 nor the I-401 accomplished anything of military benefit. About all they were able to do was train for air attack missions that would never transpire.

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STRATEGIC SHIFTS: The I-400 Class was the brainchild of Japanese Admiral Yamamoto, Commander-in-Chief of the Japanese Combined Fleet. Shortly after the Pearl Harbor attack on December 7, 1941, he conceived the idea of attacking the Continental United States by using sub-based aircraft. Strategically sized to circumnavigate the world without need for refueling, they were theoretically capable of not only attacking America’s west coast, but also its more populous and industrialized east coast. In early 1942, the Japanese government authorized construction of eighteen of the large subs and development of attack aircraft suitable for use as Yamamoto envisioned. Detailed design of both subs and aircraft took place during 1942. Construction of the lead boat if the I-400 Class was started in January 1943. But by then, the war was already going badly for Japan. Priority was given to replacing the aircraft carriers lost in the Battle of Midway, and consequently the number of I-400 Class submarines was reduced...from eighteen to nine and then five; only three of which were ever completed. Since United States warships were coming off the ways in numbers that the Japanese could not hope to equal, a change in strategy was initiated. To help stem the tide of vessels being built on America’s east coast of America, the mission of the I-400 Class embarked aircraft was shifted to bomb and disable the Panama Canal’s vulnerable locks. But before even the first of the subs could be completed, Japan had been reduced to fighting for its very survival, and the strategic use of the I-400 Class boats reverted to participating in more traditional submarine warfare. But that ultimate shift in strategy came far too late to make any difference. STORM FROM A CLEAR SKY: The sleek aircraft created for use with these submarines was the M6A1 Seiran (translates, roughly as storm from a clear sky) torpedo bomber. These float planes were 35 feet long and had a wingspan of 40 feet. Their weapons’ payload consisted of 1,800 pounds of either torpedoes or aerial bombs. In order to fit in the submersibles’ hangars, they had to have their floats detached, and their wings and tails folded. But once on the surface a well- trained crew could rig one of these aircraft for launch, including fuelling and arming, in as little as seven minutes.

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UNCONDITIONAL SURRENDER: When the war ended, the two operational I-boat’s crews were at sea, preparing for a planned air attack on American forces at one of the many island bases in the Western Pacific. Unaware of the atomic bomb attacks, they were shattered when orders were received from Tokyo to cease all hostilities, jettison all their offensive armament and return home, on the surface. In late August 1945, the I-400, I-401 and some smaller submarines were intercepted off Honshu by American forces. On August 28th, the I-400 struck her colors at sea and the American flag was hoisted in its place. This somewhat grainy image captures that historic event. With Americans observers onboard, she and the several other Japanese subs continued on their way to Sasebo Bay, where their many novel features were inspected by American naval officers who were astounded by their size. Then came the necessity to decide what to do with them.

DISMANTLING THE JAPANESE SUB FLEET: When World War II ended in August 1945, Lieutenant Thomas Paine was Engineering and Diving Officer of the USS POMPON (SS-267). Over a period of two years, he had made seven combat patrols with his POMPON shipmates. But when she was sent home, he was left behind. Transferred to a submarine tender moored at Guam, he was assigned to learn as much Japanese as possible. A month later, he stepped ashore in Japan to participate in the demilitarization of Japan's submarine force. In his own words: "I landed at the Sasebo Naval Base with the first boatload of marines; my orders were to seize samples of every type of torpedo, spare parts and tools. Our first hours in Japan were extremely tense - rumors flew, and nobody really knew what to expect. We were well armed and prepared to deal with resistance. Both sides was relieved when an orderly surrender took place. "I soon found myself presented with a Japanese naval officer's sword and a detail of Japanese technical personnel to help me assemble my torpedoes and ordnance equipment. They spoke no English, so my broken Japanese began to improve through constant usage."

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"My torpedo collecting was just a side-line to our primary mission, which was to locate and disarm the Japanese submarine fleet, interrogate the crews, study the material and, when ordered, scuttle the boats." By mid-November, a large number of Japanese subs slated to be scuttled were moored in Sasebo harbor. Because of their unique design features, the giant boats I-400 and I-401 were selected for relocation to Pearl Harbor for a detailed study of their features. Accordingly, US Navy Prize Crews consisting of experienced submariners were organized for this purpose. Lieutenant Thomas Paine was assigned as Executive Officer and Navigator of the I-400's prize crew.

ADAPTING TO SEN TOKU I-400: Prior to receiving that assignment, he had been aboard I-402 briefly, and had been surprised by her curious mix of aircraft handling gear, the size and number of her compartments and the bizarre offset position of her conning tower. But that had been but a cursory tour. In order to properly prepare for a long trans-Pacific voyage, the I-400's prize crew had to first get intimately acquainted with their complex new home. This meant essentially repeating what they had had to do to earn their submarine dolphins...but complicated by the absence of any English language plans, manuals, or label plates. Fortunately, Japanese submarine design practices were similar to those used in the United States. A representative group of Japanese crew members, detained to help with the familiarization effort...albeit with various degrees of resistance...provided translations and explanations. Perhaps even more invaluable they also imparted to the Americans some unwritten....and often 'tricks of the trade' that unofficially exist in every navy. "Our prize crew soon produced their own working drawings by tracing every system, and then under the watchful eye of Japanese petty officers, we operated the sub's engines, and other equipment. We hung so many hand-lettered tags on essential valves and equipment that the I-400's interior looked like an inside-out Christmas tree."

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Part of the I-400's prize crew's preparation for making a long ocean voyage included requisitioning stores from the Navy's sub tender and undertaking less formal acquisition of any Japanese spare parts or supplies from the warehouses of Sasebo's navy base. This latter effort including entering caves where vital supplies had been placed during the war to shelter them from American air raids. In the finest tradition of the Navy's very unofficial but time-honored 'midnight requisition' practices, Lt. Paine and his men also gathered some 'essentials' which they stored in I-400's cavernous airplane hangar. "The I-400 quickly became history's first Undersea Inter-island Trader. Overnight our hangar became an armory suitable for a major gun running operation, with stacks of commandeered rifles and bayonets. In addition, we added Japanese uniform buttons and rating badges, rubber stamps and even a sampan to stock our Submarine War Surplus Store. "In order to avoid unduly draining the sub tender of its limited supplies, we loaded provisions for only 14 days to carry us through the first leg of our passage to Guam, where we could get enough food for the rest of the voyage to Hawaii. By the end of November we were able to report the I-400 'in all respects ready for sea'." OUTWARD BOUND: "We got underway on December 11, 1945, bound for Pearl Harbor in the company of I-401 and one other, smaller Japanese sub. Our little flotilla was escorted by the submarine rescue vessel USS GREENLET (ASR-10), which carried deep sea towing gear...just in case.."

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The four vessels sailed in loose formation at a rate of advance of twelve knots. Floating mines were the main concern. A submariner's worst fear when running on the surface...a sudden attack by undetected enemy aircraft...no longer existed. "I-400's high freeboard, broad beam, deep draft and ample bow buoyancy tank gave her a dry bridge and an easy roll and pitch. She was a comfortable boat in a seaway. Her 130 foot long gun platform atop the hangar gave us a promenade deck worthy of the RMS Queen Mary. "The I-400's diesels pounded steadily on, driving us southeast on a 1200 mile leg of our voyage. Soon we discovered a culinary drawback of the I-400: fewer fresh flying fish on deck each morning for breakfast than we'd have collected with a fleet submarine's lower freeboard." When they arrived at Guam's submarine base, the four vessels were met with a tumultuous welcome...whistles blowing and bands playing. Since the end of the war Guam had become an isolated and dull back-water base. The arrival of the huge I-boats flying the stars and stripes over the rising sun was a happy 'event'. Throngs of visitors marveled at the airplane hangars, the catapults and the very large deck guns of I-400 and I-401.

I-BOAT BUCCANEERS GO INTO ACTION: The small squadron requisitioned and received ample provisions and other supplies through official Navy channels. Enlisted members of the prize crew of I-400 augmented that effort through horse trade and another time honored navy tradition...cumshaw. " Guam was crammed with unneeded supplies and equipment, so our crew quickly opened our floating flea market for trading. Archaeologists who someday dive on the I-400 in deep water off Hawaii will surely wonder why her scuttlebutts were equipped with General Electric refrigerated fountains. Why did her galley feature gourmet cooking equipment...including an ice cream machine? Why deluxe porcelain plumbing fixtures in the heads? Why bunks wired for music from a deluxe jukebox"?

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Such activities, augmented by 'midnight requisitions' inevitably led to trouble. One morning, an irate Marine lieutenant stormed onboard I-400, demanding the return of his personal motor scooter. Discreet inquiry pointed to the real culprit; his double-dealing motor pool sergeant, but the I-400's Chief of the Boat reassured Lt. Paine that nobody was going to find any motor scooter in their sub. "That was not quite the same as saying that the lieutenant's motor scooter was not aboard, but I believed our chief: nobody was going to find it. Clearly the time had come to crack down on our I-Boat bazaar, so our no-nonsense skipper lowered the boom on our pirates while, in the tradition of Queen Elizabeth I, we enjoyed the fruits of their buccaneering. "With our war prize now lavishly stocked and well equipped, we set sail from Guam for the next 1000-mile leg of our voyage. Christmas Eve found us cruising through tropic seas approaching Eniwetok. Our hard-bitten captain was moved to express his feelings in this poetic Christmas Greeting he posted in the Control Room for the I-Boat Buccaneers":

CHRISTMAS AT SEA, 1945 A Merry Christmas, which I know Is better here than in Sasebo! Next Christmas, and the ones to come I hope all hands will spend at home. Let's hope and pray that ne'er again Must we spend Christmas killing men, That peace will reign beyond our time, No guns compete with Christmas chimes. Let's offer thanks for where we are, For Christmas time not spent at war, And honor those who gave their lives, While we head home toward our wives.

-- Commander J. M. McDowell, U.S.N. Commanding Officer, ex-H.I.J.M.S. I-400.

The stop in Eniwetok paralleled the Guam experience. It was a less lengthy stay, but nevertheless not short enough to keep the I-400 prize crew out of hot water. This time, the Island Commander's jeep mysteriously disappeared. A thorough search of the three captured subs and their escort vessel failed to turn up any clues. At that point, the four vessels were given permission to sail. In fact, they were told by the Island Commander 'to get the hell out and not come back'.

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"I don't know what happened to that jeep, but the I-401 crew flaunted a newly-painted one in Pearl Harbor they said they'd purchased with their welfare fund (we thought our racy motor scooter had more class)!

"New Year's Eve found us steaming eastward for Hawaii on a course laid out to take us under the lee of Johnson Island in case one of the boats had to heave to for repairs. Submarine custom decrees that the deck log entry for the last watch of the year be written in rhyme. Our Engineering Officer had the last watch of 1945 and created the obligatory poem; complete with all essential log entries regarding course, speed, etc.".

ALOHA: On January 6th, 1946, they sailed triumphantly into Pearl Harbor. As the I-400 moved slowly past the gutted hulk of the USS ARIZONA, her American and Japanese ensigns were dipped in salute. Once in port, the I-Boat Buccaneers hung this celebratory banner, which had been created during their epic voyage on the I-400's conning tower. And then...the I-Boat Buccaneers' voyage was over. I-400 was placed in dry dock so Navy design experts could explore her secrets. By mid-February 1946, they had finished, and I-400 was moved to a pier alongside I-401 to await final disposition.

Lt. Paine urged the authorities to conduct a trial submergence to help evaluate the I-400's automatic trim system. Instead, after the Navy had extracted all there was to know about the submarines' unusual design, the Japanese subs were consigned for target practice. In the middle of 1946, they were towed to an area in the Pacific off Hawaii where the water is extremely deep and sunk.

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The remaining Sen Toku, I-402, which had been commissioned in late July of 1945 and never saw any service, left Sasebo in early 1946. Her only sea voyage was made at the end of a tow line. She was sunk as a target near Japan.

Ironically, submarine-fired torpedoes were used to finish off all three.

POSTSCRIPT: The son of a Navy Commodore, Thomas O. Paine received an engineering degree in 1942; after which he followed in his father's naval footsteps. Returning to civilian life later in 1946, Thomas Paine earned advanced degrees in physical metallurgy from Stanford. That same year he married an Australian miss whom he had met while on Liberty in Perth during the war. They cut their wedding cake with his souvenir Japanese sword. In 1949 he went to work for General Electric where he was engaged in advanced metallurgical studies until 1968. That year, he was appointed Deputy Administrator of NASA and the next year Dr. Paine was promoted to the post of NASA Administrator. During his tenure in that position, the first seven Apollo manned missions to the moon were flown. In his memoirs, he included this little known tidbit of intriguing and unique submarine service/space exploration history:

"My lucky gold dolphins went to the Moon with Neil Armstrong".

Dr. Paine left NASA in 1970 and returned to work at GE, where he remained until retiring in 1976. In 1985 the White House chose Thomas Paine as chairman of a National Commission on Space to prepare a report on the future of space exploration. The Paine Commission's report was published in May 1986. It created a blueprint for exploring and settling the solar system and outlined a long-range space program for the United States, including several of NASA's current activities. In addition to receiving a Ph.D from Sanford, later in life he also received honorary doctor of science degrees from six other universities. Dr. Paine served on a number of prestigious scientific committees and often spoke to technical societies before succumbing to cancer in 1992.