The anti-torpedo bulge (also known as an anti-torpedo blister) is a form of defence against naval torpedoes occasionally employed in warship construction in the period between the First and Second World Wars. It involved fitting (or retrofitting) partially water-filled compartmentalized sponsons on either side of a ship's hull, intended to detonate torpedoes, absorb their explosions, and contain flooding to damaged areas within the bulges.
 |
Essentially, the bulge is a compartmentalized, below the waterline sponson isolated from the ship's internal volume. It is part air-filled, and part free-flooding. In theory, a torpedo strike will rupture and flood the bulge's outer air-filled component while the inner water-filled part dissipates the shock and absorbs explosive fragments, leaving the ship's main hull structurally intact. Transverse bulkheads within the bulge limit flooding to the damaged area of the structure.
The bulge was developed by the British Director of Naval Construction, Eustace Tennyson-D'Eyncourt, who had four old Edgar-class protected cruisers so fitted in 1914. These ships were used for shore bombardment duties, and so were exposed to inshore submarine and torpedo boat attack. Grafton was torpedoed in 1917, and apart from a few minor splinter holes, the damage was confined to the bulge and the ship safely made port. Edgar was hit in 1918; this time damage to the elderly hull was confined to dented plating.
The Royal Navy had all new construction fitted with bulges from 1914, beginning with the Revenge-class battleships and Renown-class battlecruisers. It also had its large monitors fitted with enormous bulges. This was fortunate for Terror, which survived three torpedoes striking the hull forward, and for her sister Erebus, which survived a direct hit from a remotely-controlled explosive motor boat that ripped off 15 metres (50 ft) of her bulge. On the other hand, the bulges to Glatton nearly led to a disaster in Dover Harbour on 11 September 1918. Glatton caught fire in her 150-millimetre (6 in) cordite magazine and had the potential to explode in proximity to a loaded ammunition ship. The admiral on hand ordered the monitor scuttled to prevent a catastrophic explosion. The first attempt to do so with 460-millimetre (18 in) torpedoes failed due to the protective effect of the bulges. Half an hour later, a larger, more powerful 530-millimetre (21 in) torpedo was able to sink Glatton by striking the hole caused by the initial, ineffective hit. [1]
Older ships also had bulges incorporated during refit, such as the U.S. Navy's Pennsylvania class, laid down during World War I and retrofitted 1929–31. Japan's Yamashiro had them added in 1930.
Later designs of bulges incorporated various combinations of air and water filled compartments and packing of wood and sealed tubes. As bulges increased a ship's beam, they caused a reduction in speed, which is a function of the length-to-beam ratio. Therefore, various combinations of narrow and internal bulges appeared throughout the 1920s and into the 1930s. The external bulge had disappeared from construction in the 1930s, being replaced by internal arrangements of compartments with a similar function. An additional reason for the bulges' obsolescence was advances in torpedo design. In particular, deployment of magnetic pistol and magnetic proximity fuze in the early 1940s allowed torpedoes to run beneath a target's hull and explode there, beyond the bulges, rather than needing to strike the side of the ship directly. However, older ships were still being fitted with new external bulges through World War II, particularly US ships. In some cases this was to restore buoyancy to compensate for wartime weight additions, as well as for torpedo protection.
The Tennessee class consisted of two dreadnought battleships—Tennessee and California—built for the United States Navy in the late 1910s, part of the "standard" series. The class was in most respects a repeat of the preceding New Mexico class, with the primary improvements being a significantly strengthened underwater protection system, and increased elevation of the main battery guns to allow them to fire at much greater ranges. They carried the same main battery of twelve 14-inch (356 mm) guns in four triple turrets, and had the same top speed of 21 knots. Both ships served in the Pacific Fleet for the duration of their careers, which included an extensive training program during the interwar period of the 1920s and 1930s.
The Wyoming class was a pair of dreadnought battleships built for the United States Navy. Wyoming and Arkansas were authorized in early 1909, and were built between 1910 and 1912. These were the fourth dreadnought design of the US Navy, but only an incremental improvement over the preceding Florida class, and the last US battleships to use 12-inch guns. The primary changes were the adoption of a more powerful 12 in (305 mm)/50 caliber Mark 7 gun, addition of a sixth twin-gun turret and improved armor protection, including the first use of a torpedo bulkhead on American battleships. The Navy considered using more powerful 14-inch (356 mm) guns, but this would have caused delays and required larger docks.
HMS Erebus was a First World War monitor launched on 19 June 1916 and which served in both world wars. She and her sister ship Terror are known as the Erebus class. They were named after the two bomb vessels sent to investigate the Northwest Passage as part of Franklin's lost expedition (1845–1848), in which all 129 members eventually perished.
The Kirov-class cruisers were a class of six cruisers built in the late 1930s for the Soviet Navy. After the first two ships, armor protection was increased and subsequent ships are sometimes called the Maxim Gorky class. These were the first large ships built by the Soviets from the keel up after the Russian Civil War, and they were derived from the Italian cruiser Raimondo Montecuccoli, being designed with assistance from the Italian Ansaldo company. Two ships each were deployed in the Black and Baltic Seas during World War II, while the last pair was still under construction in the Russian Far East and saw no combat during the war. The first four ships bombarded Axis troops and facilities after the Germans invaded the Soviet Union in June 1941. All six ships survived the war and lingered in training and other secondary roles, with three being scrapped in the early 1960s and the other three a decade later.
Shinano was an aircraft carrier built by the Imperial Japanese Navy (IJN) during World War II, the largest such built up to that time. Laid down in May 1940 as the third of the Yamato-class battleships, Shinano's partially complete hull was ordered to be converted to an aircraft carrier following Japan's disastrous loss of four of its original six fleet carriers at the Battle of Midway in mid-1942. The advanced state of her construction prevented her conversion into a fleet carrier, so the IJN decided to convert her into a carrier that supported other carriers.
Taihō was an aircraft carrier of the Imperial Japanese Navy during World War II. Possessing heavy belt armor and featuring an armored flight deck, she represented a major departure from prior Japanese aircraft carrier design and was expected to not only survive multiple bomb, torpedo, or shell hits, but also continue fighting effectively afterwards.
HMS Gorgon and her sister ship Glatton were two monitors originally built as coastal defence ships for the Royal Norwegian Navy, as HNoMS Nidaros and Bjørgvin respectively, by Armstrong Whitworth at Elswick. She was purchased from Norway at the beginning of the First World War, but was not completed until 1918 although she had been launched over three years earlier. She engaged targets in Occupied Flanders for the last several months of the war and fired the last shots of the war against such targets on 15 October 1918. She was used as a target ship after several attempts to sell her had fallen through before being sold for scrap in 1928.
HMS Terror was an Erebus-class monitor built for the Royal Navy during the First World War in Belfast. Completed in 1916, she was assigned to the Dover Patrol where her primary duties involved bombarding German targets on the coast of occupied Belgium, particularly at the ports of Zeebrugge and Ostend. In October 1917 Terror was hit by three torpedoes, taking severe damage to the bow, and had to be towed into Portsmouth for repair. In April 1918 she participated in the Zeebrugge raid and provided gunnery support for the Fifth Battle of Ypres in September of the same year.
The torpedo belt was part of the armoring scheme in some warships between the 1920s and 1940s. It consisted of a series of lightly armored compartments, extending laterally along a narrow belt that intersected the ship's waterline. In theory this belt would absorb the explosions from torpedoes, or any naval artillery shells that struck below the waterline, and thus minimize internal damage to the ship itself.
Amagi (天城) was an Unryū-class aircraft carrier built for the Imperial Japanese Navy during World War II. Named after Mount Amagi, and completed late in the war, she never embarked her complement of aircraft and spent the war in Japanese waters. The ship capsized in July 1945 after being hit multiple times during airstrikes by American carrier aircraft while moored at Kure Naval Base. Amagi was refloated in 1946 and scrapped later that year.
Belt armor is a layer of heavy metal armor plated onto or within the outer hulls of warships, typically on battleships, battlecruisers and cruisers, and aircraft carriers.
The Tosa-class battleships were two dreadnoughts ordered as part of the "Eight-Eight" fleet for the Imperial Japanese Navy (IJN) during the early 1920s. The ships were larger versions of the preceding Nagato class, and carried an additional 41-centimeter (16.1 in) twin-gun turret. The design for the class served as a basis for the Amagi-class battlecruisers.
Katsuragi (葛城) was the third and final Unryū-class aircraft carrier of the Imperial Japanese Navy built during World War II. Named after Mount Katsuragi, in Nara Prefecture, and completed late in the war; she never embarked her complement of aircraft and spent the war in Japanese waters. The ship was badly damaged in a July 1945 airstrike by American carrier aircraft on Kure Naval Base. Repaired after the end of the war, Katsuragi was then used as a repatriation transport for a number of months, bringing Japanese soldiers and civilians back to Japan from overseas locations. She was scrapped in Japan beginning in late 1946.
The Nagato-class battleships were a pair of dreadnought battleships built for the Imperial Japanese Navy (IJN) towards the end of World War I, although they were not completed until after the war. The last of Japan's pre-Treaty capital ships, they were the first class to carry 41 cm (16.1 in) guns, the largest afloat at the time and the first bigger than 15 inches (381 mm). Nagato, the lead ship of the class, frequently served as a flagship. Both ships carried supplies for the survivors of the Great Kantō earthquake in 1923. They were modernized in 1933–1936 with improvements to their armor and machinery and a rebuilt superstructure in the pagoda mast style. Nagato and her sister ship Mutsu briefly participated in the Second Sino-Japanese War in 1937 and Nagato was the flagship of Admiral Isoroku Yamamoto during the attack on Pearl Harbor on 7 December 1941 that began the Pacific War.
HMS Glatton and her sister ship Gorgon were originally built as coastal defence ships for the Royal Norwegian Navy, as Bjørgvin and Nidaros respectively. She was requisitioned from Norway at the beginning of World War I, but was not completed until 1918 although she had been launched over three years earlier. On 16 September 1918, before she had even gone into action, she suffered a large fire in one of her 6-inch magazines, and had to be scuttled to prevent an explosion of her main magazines that would have devastated Dover. Her wreck was partially salvaged in 1926, and moved into a position in the northeastern end of the harbour where it would not obstruct traffic. It was subsequently buried by landfill underneath the current car ferry terminal.
The Gorgon-class monitors were a class of monitors in service with the Royal Navy during World War I. Gorgon and her sister ship Glatton were originally built as coastal defence ships for the Royal Norwegian Navy, as HNoMS Nidaros and HNoMS Bjørgvin respectively but requisitioned for British use. Gorgon commissioned first, in June 1918 and bombarded German positions and other targets in Occupied Flanders. She fired the last shots of the war by the Royal Navy into Belgium on 15 October 1918. She was offered for sale after the war, but was used as a target ship when there were no takers. She was sold for scrap in 1928. Glatton was destroyed by a magazine explosion only days after she was completed in September 1918 while in Dover Harbour. She remained a hazard to shipping until the wreck was partially salvaged and the remains moved out of the way during 1925–26.
A torpedo bulkhead is a type of naval armor common on the more heavily armored warships, especially battleships and battlecruisers of the early 20th century. It is designed to keep the ship afloat even if the hull is struck underneath the belt armor by a shell or by a torpedo.
Tosa (土佐) was a planned battleship of the Imperial Japanese Navy. Designed by Yuzuru Hiraga, she was envisioned as the lead ship of the Tosa class of two 39,900-long-ton (40,540 t) ships. The battleships would have been armed with ten 410 mm (16.1 in) guns and brought Japan closer to its goal of an "Eight-four" fleet. All work on the ship was halted after the Washington Naval Conference and the signing of the Washington Naval Treaty. As the vessel had to be destroyed in accordance with the terms of the treaty, the incomplete Tosa was then subjected to tests to gauge the effect of Japanese weaponry before being scuttled on 9 February 1925.
Naval armor refers to the various protections schemes employed by warships. The first ironclad warship was created in 1859, and the pace of armour advancement accelerated quickly thereafter. The emergence of battleships around the turn of the 20th century saw ships become increasingly large and well armoured. Vast quantities of heavily armoured ships were used during the World Wars, and were crucial in the outcome. The emergence of guided missiles in the last part of the 20th century has greatly reduced the utility of armor, and most modern warships are now only lightly armored.
Sfax was a protected cruiser built for the French Navy in the 1880s. She was the first vessel of the type to be built for the French Navy, which was a development from earlier unprotected cruisers like Milan. Unlike the earlier vessels, Sfax carried an armor deck that covered her propulsion machinery and ammunition magazines. Intended to be used as a commerce raider in the event of war with Great Britain, Sfax was rigged as a barque to supplement her engines on long voyages abroad. She was armed with a main battery of six 164 mm (6.5 in) guns and a variety of lighter weapons.