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The Submarine base in situated on the far side of Rabaul at Tavui (being North) over tunnel Hill turn right at Bernie Vickers trade store and picture theatre,( now long gone) Drive along Nonga road past the hospital till the road runs out, then walk to the beach for around 100mts at lands’ end turn right go around the mangroves till you reach another open beach where you would have seen a large crane jutting out water about 50 meters from the beach, at low tide this is where the Submarine base is situated. a vertical reef wall that drops over 75 meters underwater. Japanese reportedly used it to provision submarines during the war. The deep water would allow them to submerge quickly if there was an air raid.
Latitude: -4.136724 Longitude: 152.170386
Submarine Base – Japanese used this area to provision submarines. It’s located on the northern side of Rabaul, about 10 minutes from the town and it’s a vertical reef wall that drops over 75 meters underwater. Japanese used it to provision submarines here during the war from a network of tunnels dug into the side wall.
In the early years before the crane rusted away, it was a large gantry perturbing out from the reef a set of rail lines ran from the two very large caves out to the crane this was the methods of resupplying the submarines during the war years. You can see the underwater entrance into Tavui caldera this was a very interesting move, the discovery of an area suitable to navigate a submarine into a volcanic calderas saddle up to a sheer coral reef front surface reload with fuel supplies and torpedoes and be heading out to sea.
The submarine base had many uses in the war years, the structures have all but gone the big caves are filled with silt of high tides and sea rise over the years, debris can still be seen and found in some areas , but the main structure has long since rusted away. Gone are the days of walking over the reef at knee height and diving off the crane into the deep blue abyss.
Tunnels were carved in-the the side of the mountains by slave labour , these tunnels were stocked with supplies and torpedoes to supply the hunting submarines
Submarine Bay near Rabaul where deep tunnels in the coral cliffs and the remains of a small mobile crane corroborate the story that this was where submarines were victualled ; if attacked, batteries of guns in the cliff tunnels above would protect them or they would sink into the depths where the shelf of rock dropped a sheer 600 feet.1
The Crane at the Submarine base this crane was used for loading and offloading supplies torpedoes and other goods used in Rabaul by the Japanese war machine.
This was the crane as I remember in the late fifties early sixties,over the years it has totally rusted away with no sign left but a few bits of rusting scrap metal
In 1942, Japan commenced building the world's biggest submarines. The 400 foot long I-400 series had a displacement of 3,530 tons and were intended to destroy the Pacific exit of the Panama Canal. They could cruise 37,500 miles and dive to a depth of 325 feet. Each of the I-400s could carry three specially designed seaplane bombers which were dismantled and stored in a watertight hanger inside the submarine. Only three were completed before the end of the Pacific war and survived the massive American bombing of Japan's naval bases. All three were captured and destroyed by the Americans in April, 1946.
How Subs. Carry Planes
(By "The Sunday Times" Naval Correspondent.)
This drawing shows how reconnaissance planes are carried by ocean-going submarines. The plane is run out on rails from the watertight shed, and pro bably launched by catapult. Above the shed is a crane to lift it aboard again. Japanese submarines have an advance base at Rabaul (New Britain), 1860 miles from Sydney, and a main base at Truk, Japanese stronghold in the Caroline Islands, another 830 miles away. Planes operating from submarines probably have a range of no more than 500 miles. That would give ample area for daylight search for convoys within the submarine's immediate manoeuvring range.It would give range for limited night reconnaissance over land, allowing the submarine to wait off the coast at reasonable distance. Such a plane's armament would probably be negligible, and its bomb-load very small-500lb. at the most. But armament and bomb load are not important. The plane's job is reconnaissance, not destruction. The Japanese Aichi Al, 92 (type 97) would fit those specifications. It is a naval reconnaissance biplane with two floats. Its wing-span is 42ft. 7in., length 32ft 6in., and height 13ft. 1in. Its speed is less than 220 miles an hour. These float-planes are about the same size as the Super marine "Walrus" reconnaissance flying-boats which fly over Sydney from our cruisers. The "Walruses" have a span of 45ft, 10in., length of 37ft. 7in., and are 15ft. 3in. high Top speed is 135 miles an hour. The British Navy experimented in 1931 with a small float-biplane, launched along rails by a cordite-propelled catapult from a housing behind the conning tower of a submarine. Development of the tests was secret. Britain lists no plane carrying submarines now. Japan built one experimental submarine, J5, before the war, and fitted it with twin compartments on the after-deck. One compartment held the aircraft fuselage and the one beside it stored the detachable wings. Last I heard of this ship, the Japs themselves were saying it wasn't much good.
The Sen Toku I-400-class Imperial Japanese Navy submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic missile submarines in the 1960s. They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat.The I-400-class was designed with the range to travel anywhere in the world and return. A fleet of 18 boats was planned in 1942, and work started on the first in January 1943 at the Kure, Hiroshima arsenal. Within a year the plan was scaled back to five, of which only three (I-400 at Kure, and I-401 and I-402 at Sasebo) were completed.
The I-400 class submarine was the brainchild of Admiral Isoroku Yamamoto, Commander-in-Chief of the Japanese Combined Fleet. Shortly after the attack on Pearl Harbor in December 1941, he conceived the idea of taking the war to the United States mainland by making aerial attacks against cities along the US western and eastern seaboards using submarine-launched naval aircraft. He commissioned Captain Kameto Kuroshima to make a feasibility study.Yamamoto submitted the resulting proposal to Fleet Headquarters on 13 January 1942. It called for a fleet of 18 large submarines capable of making three round-trips to the west coast of the United States without refuelling or one round-trip to any point on the globe. They also had to be able to store and launch at least two attack aircraft armed with one torpedo or 800 kg (1,800 lb) bomb. By 17 March general design plans for the submarines were finalized. Construction of I-400 commenced at Kure Dock Yards on 18 January 1943, and four more boats followed: I-401 (April 1943) and I-402 (Oct 1943) at Sasebo; I-403 (Sept 1943) at Kobe and I-404 (February 1944) at Kure. Only three were completed.
Following Yamamoto’s death when his plane was shot down during an inspection tour of the Solomon Islands in April 1943, the number of aircraft-carrying submarines to be built was reduced from eighteen to nine, then five and finally three. Only I-400 and I-401 actually entered service; I-402 was completed on 24 July 1945, five weeks before the end of the war, but never made it to sea.
Each submarine had four 1,680 kW (2,250 hp) engines and carried enough fuel to go around the world one-and-a-half times—more than enough to reach the United States travelling east or west. Measuring more than 120 m (390 ft) long overall, they displaced 5,900 t (6,500 short tons), more than double their typical American contemporaries. The cross-section of its pressure hull had a unique figure-of-eight shape which afforded the necessary strength and stability to handle the weight of a large on-deck aircraft hangar. To allow stowage of three aircraft along the vessel’s centreline, the conning tower was offset to port.
Located approximately amidships on the top deck was a cylindrical watertight aircraft hangar, 31 m (102 ft) long and 3.5 m (11 ft) in diameter. The outer access door could be opened hydraulically from within or manually from the outside by turning a large hand-wheel connected to a rack and spur gear. The door was made waterproof with a 51-millimetre-thick (2.0 in) rubber gasket.Sited atop the hangar were three water-proofed Type 96 triple-mount 25 mm (1.0 in) autocannon for AA defence, two abaft and one forward the conning tower. A single 25 mm (1.0 in) autocannon on a pedestal mount was also located just abaft the bridge. One Type 11, 140 mm (5.5 in) deck gun was positioned aft of the hangar. It had a range of 15,000 m (49,000 ft.).
Eight torpedo tubes were mounted in the bow, four above and four below. There were no aft tubes. Stowed in an open recessed compartment on the forward port side, just below top deck, was a collapsible crane used to retrieve the submarine’s Seiran floatplanes. The crane had an electrically operated hoist and was capable of lifting approximately 4.5 t (5.0 short tons). It was raised mechanically to a height of 8 m (26 ft) via a motor inside the boat. The boom extended out to a length of 11.8 m (39 ft).
A special trim system was fitted to the boats, allowing them to loiter submerged and stationary while awaiting the return of their aircraft. However, operation of this system was noisy and its usefulness was in doubt.Strung along the submarine’s gunwales were two parallel sets of demagnetization cables, running from the stern to the bow planes. These were intended to dissipate the static charge that normally builds up when a boat’s hull slices through the water, causing the steel in the hull to deteriorate over time.
Electronics on board the I-400s included a Mark 3 Model 1 air search radar equipped with two separate antennas. This unit was capable of detecting aircraft out to a range of 80 km (43 nmi). The boats were also equipped with Mark 2 Model 2 air/surface radar sets with distinctive horn-shaped antennas. Each boat carried an E27 radar warning receiver, connected to both a trainable dipole antenna and a fixed non-directional antenna made up of a wire mesh basket and two metal rods. The submarines were equipped with two periscopes of German manufacture, about 12.2 m (40 ft) long, one for use during daylight and the other at night.
A special anechoic coating made from a mixture of gum, asbestos, and adhesives, based on German technology, was applied to the hulls from the waterline to the bilge keel. This was intended to absorb or diffuse enemy sonar pulses and dampen reverberations from the boat’s internal machinery, making detection while submerged more difficult. In May 1945, I-401 was fitted with a German-supplied snorkel, a hydraulically-raised air intake device allowing the boat to run its diesel engines and recharge its batteries while remaining at periscope depth. This retrofit occurred while the boat was laid up at Kure for repairs after being damaged by an American mine in April.
The hangar of the I-400s was originally designed to hold two aircraft. In 1943, however, Commander Yasuo Fujimori, Submarine Staff Officer of the Naval General Staff, requested it be enlarged. This was deemed feasible and, as remodelled, I-400s could stow up to three Aichi M6A Seiran aircraft.
The Seiran was specifically designed for use aboard the submarines and could carry an 800 kg (1,800 lb) bomb 1,000 km (620 mi) at 475 km/h (295 mph). To fit inside the narrow confines of the hangar, the wings rotated 90 degrees and folded backward hydraulically against the fuselage, the horizontal stabilizers folded down and the top of the vertical stabilizer folded over so the overall forward profile of the aircraft was within the diameter of its propeller. When deployed for flight, the aircraft had a wing span of 12 m (39 ft) and a length of 11.6 m (38 ft). A crew of four could prepare and launch all three in 45 minutes (or 15 minutes if the planes’ pontoons were not attached). As the Seiran would normally be launched at night, parts and areas of the plane were coated with luminescent paint to ease assembly in the dark.
The Seirans were launched from a 26 m (85 ft) Type 4 No. 2 Model 10 compressed-air catapult on the forward deck of the submarine. Underneath the catapult track were four high-pressure air flasks connected in parallel to a piston. The aircraft, mounted atop collapsible carriages via catapult attachment points along their fuselages, would be slung 70–75 feet along the track, though the piston itself only moved between eight and ten feet during operation.
Two sets of pontoons for the Seirans were stored in special watertight compartments located just below the main deck on either side of the catapult track. From there they could be quickly slid forward on ramps and attached to the plane’s wings. A third set of pontoons and additional spares were kept inside the hangar.
The existence of the Seiran was not known to Allied intelligence during the war.
Operational history
As the war turned against the Japanese and their fleet no longer had free rein in the Pacific, the Commander-in-Chief of the Japanese Combined Fleet, Admiral Isoroku Yamamoto, devised a daring plan to attack the cities of New York, Washington D.C., and other large American cities. Officers of I-400 in front of the plane hangar, photographed by the US Navy following the surrender of the submarine at sea, one week after the end of hostilities.
Panama Canal strike
RABAUL, NEW BRITAIN, 1946-01-21. JAPANESE NAVAL COMPRESSOR STATION ON
TAVULA POINT. THE INSTALLATION PRODUCED COMPRESSED AIR WHICH WAS USED FOR FILLING TORPEDOES.
Subs Take Food To Jap Bases
By L. .!. FITZ-HENRY
In an attempt to break the Allied air blockade of their advanced bases on the Huon Peninsula (North-east. New
Guinea) the Japanese are using submarines to land supplies at Lae and Salamaua. Since the Bismarck Sea battle, when an enemy convoy of 22 ships was destroyed, the Japanese have been markedly reluctant to risk surface ships for the supply of the Huon Peninsula garrisons and lave been running supplies in barges and other small craft under cover of darkness and bad weather. In recent weeks Allied medium bombers and attack planes have taken heavy toll of these barges and have severely bombed and strafed the enemy's inland supply lines down the Markham Valley from Madang. Yesterday's communique from General Mac Arthur's Headquarters reported further Allied air attacks on enemy installations on Labu Lagoon at Lae. Adverse weather conditions hampered observation of results, but Labu Lagoon is known as a 'hiding-out' place for enemy Barges, which sneak along the coast at night carrying supplies and ammunition from Madang. Liberator heavy bombers on Tuesday also bombed store buildings on the Salamaua isthmus. Travel Submersed To counter this Allied air block ade the Japanese are now reported to be using submarines to ferry supplies from New Britain to New 3uinea. Allied aircraft on night recon naissance have frequently reported submarine sightings in Vitiaz Strait, the narrow waterway be tween New Britain and New Guinea. It is believed that the sub marines unload at Lae at night, making the voyage from Rabaul (New Britain) or Wewak, on the far north-east coast of New Guinea, submerged in daylight. The recent abortive attempts by the Japanese to force back Australian troops in the Mubo area can be taken as an indication that, working out from their bases at Lae and Salamaua, they have been receiving fresh supplies and equipment. First indications that they were using under-water craft to break the Allied air blockade was on March 19 when Mitchell medium bombers surprised a Japanese sub marine discharging cargo in Lae Harbour and, according to the communique, destroyed it with four direct hits. Page 3: Air War Slows.
As time passes the might of thr Japanese fortres In Rabaul, the many caves that held supplies Hospitald and workshops and bomb shealters have all erodded over tine . All that ramaineof the submarine base is submerged caves rusting metal peices scatted over the area the rail tracke from cave to crane have eroded of masny yrars being under the sea
Once you could see the rusted metal from what is left over from the time the Submarine base was in full operation
THE FORMATION, EVOLUTION, AND COLLAPSE
OF THE IMPERIAL JAPANESE NAVY SUBMARINE FORCE IN WORLD WAR II
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