Imperial Japanese Navy - KAIDAI Type Submarine ==========================================================================




The Kaidai class was a type of submarine operated by the Imperial Japanese Navy before and during World War II. Type name is a shortened form of ''Kaidai Junsen Type' (Navy Large Type Submarine).

Between the years of 1925 and 1940 Japan developed it's submarine force. Their plan was to develop a submarine fleet on the basis of three type of boats. The first was a Cruiser-type submarine (Junsen) whose prototype was developed from the British K Class and the German U-139 types of the First World War. They were to be used for reconnaissance and in operating far removed from base. The second was a long range or Fleet Type (Kaidai) which was developed from the preceeding type, but with a slightly increased displacement for co-operation with the surface forces and for patrolling enemy shipping routes. The third, a medium type was originally derived from the French Schneider-Laubeuf boats of the early years of the century.

The Junsen type boats were to have operated individually, replacing cruisers in the reconnaissance role (several were equipped with floatplanes), the Kaidai was intended to operate in flotillas, in direct co-operation with the main units of the Japanese Navy. Because of this, it lead to the surface designs of the boats being developed to the maximum extent; speed, seakeeping, range and gun armament and the resulting high displacement and dimensions, limited submerged maneurability and lengthened diving times. The effectiveness of American ASW measures was to prove fatal to these large Japanese boats.

Beginning with the building of the first two prototypes between 1921 and 1922 which were derived respectfully from the British K class submarines of 1917 and the German U-139 type cruiser-submarines, also of 1917. The Japanese concentrated on the building of the Junsen type I class commissioned between 1926 and 1932 and followed by another two boats completed in 1932 and 1935, and the Kaidai type class of 1927 from which all the large cruiser and Fleet types derived.

The first Kaidai types were of a smaller dimensions and their displacements were around 1,800/2,300 tons. Maximum surface speed was around 20 knots with a maximum range of around 10,000 miles at 10 knots. All subsequent classes were developed on the basis of these submarines along with the changes and improvements dictated by experience and technological progress.

All Japanese submarines at the beginning of the war were armed with the most advanced torpedo of the entire conflict, the oxygen-propelled Type 95 21 inch, oxygen driven, wakeless torpedo capable of a run of 21,880 yds at the exceptional speed of 50 knots, or 40,000 yds at a speed of 36 knots, compared to the 15,316 yds at 28 knots and 6,126 yds at 45 knots of the American Mark XIV torpedo. The Type 95 was the submarine version of the very formidable 'Long Lance' Type 93 oxygen-driven torpedo carried by Japanese destroyers and cruisers which produced such excellent results in the battles for Guadalcanal and elsewhere. The Type 95 submarine version had a smaller 893-pound (405kg) warhead, less range, and a smaller diameter, and was intended to be fired from the standard 21-inch (533mm) torpedo tube of a submerged submarine.

With a top speed of 49-50 knots, the Type 95 was the fastest torpedo in common use by any navy at the time. Its warhead size was the largest of any submarine torpedo, and second only to the Type 93 'Long Lance' used by Japanese surface ships. Some have claimed these to be the best torpedoes of the Second World War.

During the war Japanese submarines sank 184 Allied merchantmen totalling 907,000 tons. They also sank numerous warships including the USS Yorktown, USS Wasp, and the USS Indianapolis. They also sank several submarines, miner and auxiliary vessels. Japanese submarine losses totalled 129 boats, 70 of which were sunk by surface ships, 18 by aircraft, 19 by submarine, and 22 others lost to various other causes. Losses and new boat construction were mutually compensating throughout the war. 126 submarines entered service between December, 1941 and August, 1945.

The Kaidai Junsen Type B1 class submarine (also known as the I-15 series) were the most numerous class of submarines of the Imperial Japanese Navy during World War II - almost 20 were built, of which only one (I-36) survived. The class started production with boat I-15, which gave the series their alternative name. The series was rather successful, especially at the beginning of the war.

These submarines were fast, had a very long range, and carried a single seaplane, located in a hangar in front of the conning tower, and launched via a forward catapult. Late in the war, some of the submarines had their aircraft hangar removed, to replace it with a 14 cm gun. In 1944, I-36 and I-37 were modified so that they could carry four Kaiten kamikaze manned torpedoes, with I-36 later being further modified to carry six.


I-25 was a Kaidai Junsen B1-Type (I-15 Class) submarine of the Imperial Japanese Navy that served in World War II and took part in the Attack on Pearl Harbor, and carried out one of the few attacks on the continental United States, the Lookout Air Raid incident in September 1942. She was sunk by destroyer USS Patterson off the New Hebrides on 3 September 1943.

I-25, with a displacement of 2,600 tons, was 108 metres long, with a range of 14,000 nautical miles (25,900 km), a maximum surface speed of 23.5 knots (43.5 km/h) and a maximum submerged speed of 8 knots (15 km/h). She carried a two-seater Yokosuka E14Y reconnaissance floatplane, known to the Allies as "Glen". It was disassembled and stowed in the front of the conning tower.

I-25 and three other submarines patrolled a line 120 nautical miles (222 km) north of Oahu during the Japanese attack on Pearl Harbor. After the Japanese aircraft carriers sailed west following the attack, I-25 and eight other submarines sailed eastwards to patrol the west coast of the United States. I-25 attacked a cargo ship ten miles (16 km) off the US coast. The ship managed to escape but ran aground at the mouth of the Columbia River. I-25 then returned to Kwajalein atoll, arriving on 11 January 1942 to refuel and be refurbished.

I-25 left Kwajalein atoll in the Marshall Islands on 5 February 1942 for its next operational patrol in the south Pacific. Tagami's orders were to reconnoitre the Australian harbours of Sydney, Melbourne and Hobart followed by the New Zealand harbours of Wellington and Auckland.

I-25 travelled on the surface for nine days, but as she approached the Australian coastline, she only travelled on the surface under the cover of night.

On 13 February 1942, I-25 sank the United Kingdom merchant ship "Derrymore". On Saturday 14 February 1942, I-25 was within a few miles of the coast near Sydney. The searchlights in Sydney could clearly be seen from the bridge of I-25. Tagami then took I-25 to a position 100 nautical miles (190 km) south east of Sydney.

A number of days of rough swell prevented an immediate launch of the "Glen" floatplane. They stayed submerged during the day and went back to the surface at night. Finally on Tuesday 17 February 1942 Warrant Flying Officer Nobuo Fujita took off in the "Glen" for a reconnaissance flight over Sydney Harbour. The purpose was to look at Sydney's airbase. By 07.30 Fujita had returned to I-25 and disassembled the "Glen" and stowed it in the water tight hangar. Commander Tagami then pointed I-25 southwards on the surface at 14 knots (26 km/h). By midday on Wednesday 18 February 1942 they were nearly 400 nautical miles (740 km) south east of Sydney still heading southwards.

Their next mission was a similar flight over Melbourne. Tagami decided to launch the aircraft from Cape Wickham at the northern end of King Island at the western end of Bass Strait about half way between Victoria and Tasmania. The floatplane was launched on 26 February 1942 for its reconnaissanceflight to Melbourne over Port Phillip Bay.

Fujita's next reconnaissance flight in Australia was over Hobart on 1 March 1942. I-25 then headed for New Zealand where Fujita flew another reconnaissance flight over Wellington on 8 March 1942. Fujita next flew over Auckland on 13 March 1942, followed by Fiji on 17 March 1942.

I-25 returned to its base at Kwajalein on 31 March 1942.

In June 1942, I-25 was patrolling the coast of Oregon, and shelled Battery Russell, a small coastal army installation within now decommissioned Fort Stevens. Damage was minimal. In fact, the only item of significance destroyed on the fort was a baseball backstop. On September 9, 1942, the crew again deployed the Glen, which dropped incendiary bombs over Oregon forest land, in the only time the continental United States was bombed from the air, known as "The Lookout Air Raid". The goal was to trigger wildfires across the coast, but light winds, wet weather conditions and two quick acting Fire Lookouts kept the fires under control. In fact, had the winds actually been sufficiently brisk to stoke widespread forest fires, the lightweight Glen would have been unable to fly.

I-25 was sunk less than a year later by the destroyer USS Patterson off the New Hebrides islands on September 3, 1943.



Yanagi missions were missions enabled under the Axis Powers' Tripartite Pact to provide for an exchange of personnel, strategic materials and manufactured goods between Germany, Italy and Japan. Initially, cargo ships made the exchanges, but when that was no longer possible submarines are used.

Only six submarines attempted this trans-oceanic voyage during World War II: Kaidai I-30 (April 1942), Junsen I-8 (June 1943), the German submarine U-511 (August 1943), Kaidai I-34 (October 1943), and Kaidai I-29 (November 1943).

Of these, I-30 was sunk by a mine, I-34 by the British submarine Taurus, and I-29 by the American submarine, Sawfish (assisted by Ultra intelligence). Hei-gata I-52 was the final submarine to make the attempt.


I-34 was a Kaidai Junsen Type B1 class submarine of the Imperial Japanese Navy. During World War II, While on a Yanagi mission between Japan and Germany carrying strategic raw material and knowledge, she was sunk by the British submarine HMS Taurus using Ultra intelligence.

On 15 September 1943 she was assigned to a Yanagi (exchange) mission to Lorient, France. She arrived in Singapore on 22 October 1943 to take on passengers and cargo for her mission.

I-34 loaded a cargo of raw rubber bales, tungsten, tin, quinine, medicinal opium and samples of the Japanese weapons. She departed for Penang to load passengers on 11 November 1943. Due to a delay in loading of the cargo, her passengers opted to meet her at Penang, thus saving them from death.

Unknown to Commander Irie or the crew, her movements were being tracked by Ultra intelligence, and a British submarine was sent to sink her.

She was spotted running on the surface in a rain squall by the British submarine, HMS Taurus (commanded by veteran Captain Mervyn R. G. "Dillinger" Wingfield, DSO, DSC) on 13 November 1943 in the Malacca Straits, 30 nautical miles (56 km) off the coast of Penang at 07:30.

Taurus fired a salvo of six torpedoes of which one struck I-34 below the conning tower, and she sank in 100 feet (30 m) of water. Of her 94 crew, only 14 survived to be picked up by a local junk.


I-30 was an Imperial Japanese Navy submarine of the Kaidai Junsen B1 class, during World War II. She participated in one of the Yanagi missions, aimed at connecting Japan and Nazi Germany by submarine during the conflict. She was the first Japanese submarine to actually reach Europe, when she reached the German U-Boat base in Lorient, France in 1942.

I-30 brought back various technological parts and information from France, such as radar parts, a high-performance anti-aerial cannon and various blueprints.

She made it back to Singapore, but encountered a mine on the way out from the harbour and sank with her precious cargo. Part of her cargo was salvaged by divers, but most of it was damaged beyond usefulness. It is known that blueprints and some parts of radar equipment was salvaged.


I-29, code-named Matsu ("pine tree"), was a B1 type submarine of the Imperial Japanese Navy used during World War II on two secret missions with Germany, during one of which she was sunk.

I-29 also participated in missions supporting the futile search for Allied Task Force 16, which launched the Doolittle Raid on Tokyo in April 1942.

I-29's reconnaissance of Sydney harbour on the 23rd May 1942 resulted in the Japanese midget submarine attack on Sydney Harbour.

In April 1943, I-29 was tasked with a Yanagi mission. She was commanded by Captain Masao Teraoka, submarine flotilla commander - indicating the importance of the trip. She left Penang with a cargo that included two tons of gold. She met Fregattenkapitän Werner Musenberg's Type IXD-1 U-boat, U-180 on 26 April 1943 off the coast of Mozambique.

During this meeting that lasted over 12 hours due to bad weather, the two Axis submarines swapped some very interesting passengers. U-180 transferred Netaji Subhash Chandra Bose, a leader of the Indian Independence Movement who was going from Berlin to Tokyo, and his Adjutant, Abid Hasan. I-29 in turn transferred two Japanese Navy personnel who were to study U-boat building techniques in Germany: Commander (later Rear Admiral, posthumously) Emi Tetsushiro, and Lieutenant Commander (later Captain, posthumously) Tomonaga Hideo (who is later connected with the German submarine, U-234). Both submarines returned safely to their bases. I-29 dropped off her important passenger at Sabang harbour on an isolated We island located to the north of Sumatra on 6 May 1943, instead of Penang, to avoid detection by British spies.

In December 17, 1943, I-29 was dispatched on a second Yanagi mission, this time to Lorient, France under star Japanese submarine Commander Takakazu Kinashi. At Singapore she was loaded with 80 tons of raw rubber, 80 tons of tungsten, 50 tons of tin, 2 tons of zinc, and 3 tons of quinine, opium and coffee.

In spite of Allied Ultra decrypts of her mission, I-29 managed to reach Lorient 11 March 1944. On her way she was refueled twice by German vessels. Also, she had three close brushes with Allied aircraft tracking her signals. Of special note is the interaction with six RAF aircraft including two Tse-tse De Havilland Mosquito fighters equipped with 57 mm cannons from the No. 248 RAF Squadron off Cape Penas, Bay of Biscay, and the protection provided to her during the entry into Lorient by the Luftwaffe's only Long Range Maritime Fighter Unit, V Gruppe/Kampfgeschwader 40 using Ju-88s.

She left Lorient 16 April 1944 for the long voyage home with a cargo of 18 passengers, torpedo boat engines, Enigma coding machines, radar components, a Walter HWK 509A rocket engine, and Messerschmitt Me 163 & Messerschmitt Me 262 blueprints for the development of the rocket plane Mitsubishi J8M. After an uneventful trip she arrived at Singapore in 14 July 1944, disembarking her passengers, though not the cargo.

On her way back to Kure, Japan, she was attacked at Balintang Channel, Luzon Strait near the Philippines by Commander W. D. Wilkins' "Wildcats" submarine taskforce consisting of Tilefish, Rock and Sawfish, using Ultra signal intelligence. During the evening of 26 July 1944, she was spotted by Sawfish which fired four torpedoes at her. Three hit the I-29, which sank immediately. Only one of her crew survived.

Among the dead was I-29's Commanding Officer, Commander Takakazu Kinashi, Japan's highest-scoring submarine "ace". Earlier in the war, as skipper of I-29's sister ship I-19, Kinashi torpedoed and sank the U.S. aircraft carrier U.S.S. Wasp and damaged both the battleship U.S.S. North Carolina and the destroyer O'Brien during the same attack. O'Brien later sank as a result of the torpedo damage and North Carolina was under repair at Pearl Harbor until November 16, 1942, a spectacular achievement that is still considered to this day to be the most effective torpedo salvo ever fired in naval history. Kinashi was honored by a rare 2-rank posthumous promotion to Rear Admiral.



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NB: The above text has been collected / excerpted / edited / mangled / tangled / re-compiled / etc ... from the following online sources :

IJN - KAIDAI class submarines - wikipedia article #1

IJN - KAIDAI B1 class submarines - wikipedia article #2

IJN - KAIDAI class submarine I-25 - wikipedia article #3

IJN - KAIDAI class submarine I-34 - wikipedia article #4

IJN - KAIDAI class submarine I-30 - wikipedia article #5

IJN - KAIDAI class submarine I-29 - wikipedia article #6

IJN - Submarines of the Imperial Japanese Navy - www.geocities.com/bullhead262 - article#1