Japanese Semi-Dreadnought Battlecruiser Ibuki (1909)

Name of the battlecruiser IBUKI, written in Chinese characters (kanji)

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Ibuki was built in Japan and armed with Japanese-made weapons. Like the Katori and Settsu classes, she showed Japanese naval architects' preference for the "hex" armament layout with 2 pairs of wing turrets (in this case for the 8" secondary guns). Laid down in 1905 at Kure on the Inland Sea, Ibuki was the third of Japan's home-made semi-dreadnought battlecruisers, and the first to be powered by Japanese-made turbine engines. The set-up was notable for being Japan's first use of geared turbines, which reduced the engines' great speed to a more manageable 100-150 rpm with increased power. Most early turbine ships such as the Dreadnought had their engines hard-shafted to the propeller shaft, and to avoid cavitation (the deterioration of water to form, decreasing the screws' power to push on it) had to run their engines at lower speeds, at which the engines were far less efficient than the higher rpm's. Geared turbines proved the perfect solution to both problems -- cavitation and engine efficiency -- allowing the engines to be run at their best speed and the screws to dig at their most efficient rate. It was an audacious step for Japan to select this method at such an early phase; only Germany and Great Britain had geared-turbine ships in service, and these mostly destroyers, until late in WWI. Even these advanced countries lacked the advanced gear-cutting capability to equip their great fleets of dreadnoughts with this ingenious feature, so it is not surprising that Japan did not follow up with more geared-turbine ships until the 1916 period. Meantime Ibuki's sister, the Kurama, was built at Yokosuka in the same period with conventional reciprocating engines, entering service in 1910, one year after Ibuki. With their handsome clipper bows and clean, symmetrical lines, these vessels flaunted their modernity, marking the complete abandonment of the ram. The Ibuki had straight pole masts, while the Kurama had tripod masts like the new British dreadnoughts. Following the British lead, adopted in their own ships from Settsu forward, the IJN installed a fire control and spotting station in each ship's foretop in 1912.


Plans and Specifications

Specifications for the Ibuki class:
Dimensions: 485' OA x 75'6" x 26'. LWL: 450' Displacement: 14,620 tons. Armament: (4) 12"/45 cal, (8) 8"/40, (14) 4.7", and (8) 3" guns; (5) 18" torpedo tubes. Armor: KC type throughout. 7"/4" belt; 7" turrets and barbettes; 8" conning tower; 5" upper belt; 6" secondary turrets and aft conning tower; 2" deck. Fuel capacity: 800 tons of coal std; 2,000 tons maximum. Propulsion: (16) coal-fired Miyabara boilers; [Ibuki :] (2) Brown-Curtis turbines developing 24,000 HP, shafted to twin screw. Maximum speed: 22 kts. [Kurama :] (2) 4-cyl inverted vertical triple expansion engines developing 22,500 HP, shafted to twin screw. Maximum speed: 21¼ kts. Crew: 817.

Ships in class: Ibuki Kurama.

Metric specs:
Dimensions: 148m OA x 23m x 7.92m. LWL: 137m. Displacement: 14,620 tons. Armament: (4) 305 mm/45 cal, (8) 254 mm/40, (14) 120 mm, and (8) 76 mm guns; (5) 45 cm torpedo tubes. Armor: KC type throughout. 178/102 mm belt; 178 mm turrets and barbettes; 254 mm conning tower; 127 mm upper belt; 152 mm secondary turrets and aft conning tower; 52 mm deck. Fuel capacity: 800 tons of coal std; 2,000 tons maximum. Propulsion: (16) coal-fired Miyabara boilers; [Ibuki :] (2) Brown-Curtis turbines developing 17,897 HP, geared to twin screw. Maximum speed: 41 km/hr. [Kurama :] (2) 4-cyl inverted vertical triple expansion engines developing 16,778 kW, shafted to twin screw. Maximum speed: 39.4 km/hr. Crew: 817.


Ships' Histories

The Ibukis were extremely powerful and fast ships for their day, although they were soon superseded by engineering advances and the stampede to dreadnought armament. Both produced in Japan, with guns and engines of the latest type manufactured in Japan, they signaled the IJN's independence from offshore manufacture of its warships and (together with the flood of battleships issuing from its yards at the same time) telegraphed Japan's determination to resist any military pressure from the West; the bitter memory of the Tripartite Intervention of 1895 nourished the roots of Japan's technological age militarism.


HIJMS Kurama running her trials in 1910.

Kurama showed the Rising Sun flag on her first duty, representing the Empire at the coronation of George V in 1911. This was typical of the ships' fate: to be impressive symbols of Japan's naval power. Ibuki journeyed to Thailand for the coronation of the new Thai king, Rama I, in 1910. When the Great War broke out in 1914, the 2 ships were part of Allied moves in preparation for the awful conflict that ensued. Because of a shortage of British ships in Asia, they were called upon to escort a great troop convoy of ANZAC forces to Suez in September 1914: 36 transports carrying 20,000 men and 7,500 horses. While en route across the Indian Ocean, an incident was reported by wireless from Keeling Island in the Cocos group. Although raring to fight -- her captain ordered battle ensigns hoisted and the ship cleared for battle -- Ibuki was ordered by the British to stay with the troopships while HMS Sydney departed at high speed to take on the sexy duty. Sydney surprised the commerce raider Emden, which had been detached from von Spee's squadron to raise mayhem in the Indian Ocean. The British cruiser soon reduced Emden to a hapless wreck, capturing her flamboyant captain and part of her crew. Her lust for glory suppressed, Ibuki obediently guarded the rich convoy and delivered her charges safely to Port Said. After being relieved from convoy duty, Ibuki continued the hunt for von Spee's East Asia Squadron in company with Tsukuba and the armored cruiser Asama. The Japanese squadron combed the Carolines, the Marshall Islands, and all the western Pacific north of the equator through early December, when news came of the Battle of Coronel, off the coast of Chile, a German naval victory. Now that von Spee's force had been definitely located, Ibuki was made ready to deploy to the SE Pacific, but von Spee's squadron was annihilated 4 weeks later at the Battle of the Falklands, before she had departed eastward. The ships' only brush with combat came in the Allied intervention in Siberia during the Russian Civil War of 1919-21.

It is perhaps as well these ships did not engage in front-line combat. As happened in Europe, their big-gun armament would have proven too tempting to commanding admirals, while their lean armor protection would have been too little to protect them from enemy 12" shot. These ships and the preceding Tsukuba class were the only semi-dreadnought type battlecruisers built. Like their battleship brethren, they were soon overtaken by the successful dreadnought designs. The speed of Britain's much larger battlecruisers (25½-28½ kts) particularly outclassed the Ibukis' 22 knots. While that speed was obtained by an even more reckless thinning of the vessels' armor, it was so tantalizing for the purposes of chasing down armored cruisers or armed merchantmen, as to overwhelm any preference for the semi-dreadnought style. Once again, Japan trumped the western powers in design if not in numbers, by producing the Kongo (1913). With 30-knot speed and 14-in armament, she outclassed anything in Germany's or Britain's arsenals in that fateful year. The Royal Navy was left scrambling to catch up to its own erstwhile client state, Japan, resulting in the Queen Elizabeth class fast battleships and the advanced battlecruiser Hood of 1920.

Meanwhile, both the Ibukis and the Tsukuba class battlecruisers were consigned to the wreckers under the Washington Treaty for Naval Disarmament, after only 12-13 years in commission. They were both broken up in 1923-24. With the coming of the Treaty Era, the frenetic prewar pace of capital ship development slowed to a crawl for some 13 years. With most of the holes for a battleship arms race plugged, international navies instead concentrated rivalries in the areas left open by the Treaty: cruiser development and aircraft carrier building and conversion, as well as retrofitting their old battleships.


An Ibuki Class iBook

KURAMA slowly leaving port, crowds of sailors in their whites

Kurama leaves port for a day's target practice, with an extra contingent of visiting brass crowding the flying bridge. Click here for a detailed enlarged view.

IBUKI in port - low afternoon light.

You are there! An uncannily sharp shot of Kurama in 1912 shows every rivet in her side. Click here for a incredible enlargement.

IBUKI in port - low afternoon light.

Ibuki enjoying a few hours' repose in the Marianas during the hunt for von Spee in 1914; the late afternoon sun glints off the angles of the ship's turrets. Click here for a super enlargement.


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