Diagram of common elements of warship armor. The belt armor (A) is on the exterior, at the waterline. Also indicated is the main deck (B), the sloping deck armor (C), and the torpedo bulkhead (D).
The belt armor is designed to prevent projectiles from penetrating to the heart of a warship. When struck by an artillery shell or underwater torpedo, the belt armor either absorbs the impact and explosion with its sheer thickness and strength, or else uses sloping to redirect the projectile and its blast downwards.
Typically, the main armor belt covers the warship from its main deck down to some distance below the waterline. If, instead of forming the outer hull, the armor belt is built inside the hull, it is installed at a sloped angle for improved protection, as described above.
Armor and underwater protection of King George V and Tirpitz.Belt armor on damaged USS Oklahoma (BB-37).
Frequently, the main belt's armor plates were supplemented with a torpedo bulkhead spaced several meters behind the main belt, designed to maintain the ship's watertight integrity even if the main belt was penetrated. Furthermore, the outer spaces around the main belt in some designs were filled with storage tanks that could contain fuel oil, seawater, or fresh water. The liquids in these tanks absorb or scatter much of the explosive force of warheads and shells. In other designs, the outer spaces were left empty, allowing some of the initial blast wave to dissipate, while the inner liquid layers then absorbed shrapnel and spread the shock wave out over a larger area. To deal with the leakage from the tanks and incoming seawater, an armored holding bulkhead prevented liquid from entering other parts of the ship. This multilayer design is featured in the cross-sectional drawings of Tirpitz and King George V.[1]
A warship can be seriously damaged underwater not only by torpedoes, but also by heavy naval artillery shells that plunge into the ocean very close to the targeted ship. Such shells which are usually armor-piercing shells (AP shells) can pass through a short stretch of water and strike the warship some distance below the waterline. In 1914 typical AP shells were expected to punch a hole in the exterior plate and detonate there with a destructive effect similar to a torpedo. However by the 1940s, advances in AP shell technology incorporated delayed fuses which give AP shells deep penetration capability before exploding; such AP shells will typically make a smaller hole than a torpedo in breaching a ship's hull, but detonating beyond the belt in the hull can cause splinter damage to machinery spaces and secondary magazines, which in turn compromises watertight integrity and encourages progressive flooding.[2] To improve protection against both shells and torpedoes, an air space can be added between the torpedo belt and the hull to increase the buoyancy of the warship.
Some kinds of naval warships have belt armor thinner than actually necessary for protection against projectiles. This is common especially with battlecruisers and aircraft carriers to reduce their weight, thus increasing their acceleration and speed. For battlecruisers, sacrificing armor for speed and firepower was a valid tradeoff as long as they were pitting against smaller weaker opponents like cruisers whose guns were unable penetrate the reduced armor of battlecruisers. Another possible reason is to meet treaty restrictions on ship displacement; one such method is all-or-nothing armoring, where belt armor is stripped from areas deemed non-vital to the functioning of the ship in battle. Agility gained from such processes is a great asset to offensive warships, which seek to quickly bring their heavy striking power to the enemy.
Aircraft carriers
Aircraft carriers typically had even thinner belt armor, despite being expected to face the threat of dive bombers and torpedo bombers more so than other warships. Unlike battleships and battlecruisers, aircraft carriers were not expected to face torpedoes and naval artillery from other surface ships, instead being deployed at a stand-off distance while being escorted by destroyers and cruisers. The fleet carrier's main hope of survival were fighters (often organized into a combat air patrol), anti-aircraft guns on the escorting ships and the carrier itself, and the carrier's high speed and maneuverability (see below - originally meant to facilitate launch and recovery of its airwing) to dodge torpedoes. Consequently, fleet carriers often suffered critical damage from even a single torpedo hit, such as in the case of USSSaratoga.
The British designed and constructed their carriers with armored flight decks, which did reduce their aircraft complement and its associated striking and combat air patrol capabilities, but the deck armor was a successful passive defense prior to the establishment of a successful fighter defenses (which required effective radar, high-speed monoplanes, and coordination).
In carriers, the maneuverability is exploited when deploying and recovering aircraft. Since planes take off and land most easily when flying into the wind, the aircraft carrier steams rapidly into the wind in both maneuvers, making take-off and landing safer and easier. To this end, nearly all large aircraft carriers have had speeds of 30 knots or more: for example, the sister shipsUSSLexington and USSSaratoga, the second and third aircraft carriers to enter the U.S. Navy, in 1927.
↑ Czarnecki, Joseph (January 31, 2001). "Torpedo Defense Systems of World War II". NavWeaps. Tony DiGiulian. Retrieved August 18, 2020. Dreadnought Battleships and Battlecruisers Torpedoed or Mined in Combat / Man-placed limpets and under hull ground mines / KM Tirpitz, Date: 22-Sep-43, Hits: 3, Notes: Immobilized. Machinery deranged.
↑ Lundgren, Robert (September 28, 2010). "Kirishima Damage Analysis"(PDF). NavWeaps. Tony DiGiulian. Retrieved August 19, 2021.
The armored cruiser was a type of warship of the late 19th and early 20th centuries. It was designed like other types of cruisers to operate as a long-range, independent warship, capable of defeating any ship apart from a battleship and fast enough to outrun any battleship it encountered.
A warship or combatant ship is a ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as being armed, warships are designed to withstand damage and are typically faster and more maneuverable than merchant ships. Unlike a merchant ship, which carries cargo, a warship typically carries only weapons, ammunition and supplies for its crew.
The Iowa class was a class of six fast battleships ordered by the United States Navy in 1939 and 1940. They were initially intended to intercept fast capital ships such as the Japanese Kongō class and serve as the "fast wing" of the U.S. battle line. The Iowa class was designed to meet the Second London Naval Treaty's "escalator clause" limit of 45,000-long-ton (45,700 t) standard displacement. Beginning in August 1942, four vessels, Iowa, New Jersey, Missouri, and Wisconsin, were completed; two more, Illinois and Kentucky, were laid down but canceled in 1945 and 1958, respectively, before completion, and both hulls were scrapped in 1958–1959.
The Colorado-class battleships were a group of four United States Navy super-dreadnoughts, the last of its pre-Treaty battleships. Designed during World War I, their construction overlapped the end of that conflict and continued in its immediate aftermath. Though all four keels were laid, only three ships entered service: Colorado, Maryland, and West Virginia. Washington was over 75% completed when she was canceled under the terms of the Washington Naval Treaty in 1922. As such, the 16" gun Colorado-class ships were the last and most powerful battleships built by the U.S. Navy until the North Carolina class entered service on the eve of World War II.
The Alaska-class were six large cruisers ordered before World War II for the United States Navy (USN), of which only two were completed and saw service late in the war. The USN designation for the ships of this class was 'large cruiser' (CB), a designation unique to the Alaska-class, and the majority of leading reference works consider them as such. However, various other works have alternately described these ships as battlecruisers despite the USN having never classified them as such, and having actively discouraged the use of the term in describing the class. The Alaskas were all named after territories or insular areas of the United States, signifying their intermediate status between larger battleships and smaller heavy and light cruisers.
Haruna was a warship of the Imperial Japanese Navy during World War I and World War II. Designed by the British naval engineer George Thurston, she was the fourth and last battlecruiser of the Kongō class, amongst the most heavily armed ships in any navy when built. Laid down in 1912 at the Kawasaki Shipyards in Kobe, Haruna was formally commissioned in 1915 on the same day as her sister ship, Kirishima. Haruna patrolled off the Chinese coast during World War I. During gunnery drills in 1920, an explosion destroyed one of her guns, damaged the gun turret, and killed seven men.
Kongō was a warship of the Imperial Japanese Navy during World War I and World War II. She was the first battlecruiser of the Kongō class, among the most heavily armed ships in any navy when built. Her designer was the British naval engineer George Thurston, and she was laid down in 1911 at Barrow-in-Furness in Britain by Vickers Shipbuilding Company. Kongō was the last Japanese capital ship constructed outside Japan. She was formally commissioned in 1913, and patrolled off the Chinese coast during World War I.
Kirishima was a warship of the Imperial Japanese Navy which saw service during World War I and World War II. Designed by British naval engineer George Thurston, she was the third launched of the four Kongō-class battlecruisers. Laid down in 1912 at the Mitsubishi Shipyards in Nagasaki, Kirishima was formally commissioned in 1915 on the same day as her sister ship, Haruna. Kirishima patrolled on occasion off the Chinese coast during World War I, and helped with rescue efforts following the 1923 Great Kantō earthquake.
SMS Blücher was the last armored cruiser built by the German Empire. She was designed to match what German intelligence incorrectly believed to be the specifications of the British Invincible-class battlecruisers. Blücher was larger than preceding armored cruisers and carried more heavy guns, but was unable to match the size and armament of the battlecruisers which replaced armored cruisers in the British Royal Navy and German Imperial Navy. The ship was named after the Prussian Field Marshal Gebhard von Blücher, the commander of Prussian forces at the Battle of Waterloo in 1815.
The Scharnhorst class was a class of German battleships built immediately prior to World War II. The first capital ships of Nazi Germany's Kriegsmarine, it comprised two vessels: Scharnhorst and Gneisenau. Scharnhorst was launched first, and is considered to be the lead ship by some sources; they are also referred to as the Gneisenau class in some other sources, as Gneisenau was the first to be laid down and commissioned. They marked the beginning of German naval rearmament after the Treaty of Versailles. The ships were armed with nine 28 cm (11 in) SK C/34 guns in three triple turrets; plans to replace these with six 38 cm (15 in) SK C/34 guns in twin turrets were never realized.
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.
The Admiral-class battlecruisers were to have been a class of four British Royal Navy battlecruisers built near the end of World War I. Their design began as an improved version of the Queen Elizabeth-class battleships, but it was recast as a battlecruiser after Admiral John Jellicoe, commander of the Grand Fleet, pointed out that there was no real need for more battleships, but that a number of German battlecruisers had been laid down that were superior to the bulk of the Grand Fleet's battlecruisers and the design was revised to counter these. The class was to have consisted of HMS Hood, Anson, Howe, and Rodney — all names of famous admirals — but the latter three ships were suspended as the material and labour required to complete them was needed for higher-priority merchantmen and escort vessels. Their designs were updated to incorporate the lessons from the Battle of Jutland, but the Admiralty eventually decided that it was better to begin again with a clean-slate design so they were cancelled in 1919. No more battlecruisers would be built due to the arms limitations agreements of the interbellum.
The South Dakota class was a group of four fast battleships built by the United States Navy. They were the second class of battleships to be named after the 40th state; the first were designed in the 1920s and canceled under the terms of the Washington Naval Treaty. Four ships comprised the class: South Dakota, Indiana, Massachusetts, and Alabama. They were designed to the same treaty standard displacement limit of 35,000 long tons (35,600 t) as the preceding North Carolina class and had the same main battery of nine 16"/45 caliber Mark 6 guns in three-gun turrets, but were more compact and better protected. The ships can be visually distinguished from the earlier vessels by their single funnel, compared to twin funnels in the North Carolinas.
All or nothing is a method of naval warship armor, best known for its employment on dreadnought battleships. The concept involves heavily armoring the areas most important to a ship while the rest of the ship receives no armor. The "all or nothing" concept avoided light or moderate thicknesses of armor: armor was used in the greatest practicable thickness or not at all, thereby providing "either total or negligible protection". Compared to previous armoring systems, "all or nothing" ships had thicker armor covering a smaller proportion of the hull.
The Derfflinger class was a class of three battlecruisers of the Imperial German Navy. The ships were ordered for the 1912–13 Naval Building Program of the German Imperial Navy as a reply to the Royal Navy's two new Lion-class battlecruisers that had been launched a few years earlier. The preceding Moltke class and the incrementally improved Seydlitz represented the end of the evolution of Germany's first generation of battlecruisers. The Derfflinger class had considerable improvements, including a larger primary armament, all of which was mounted on the centerline. The ships were also larger than the preceding classes. The Derfflinger class used a similar propulsion system, and as a result of the increased displacement were slightly slower.
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.
World War II saw the end of the battleship as the dominant force in the world's navies. At the outbreak of the war, large fleets of battleships—many inherited from the dreadnought era decades before—were one of the decisive forces in naval thinking. By the end of the war, battleship construction was all but halted, and almost every remaining battleship was retired or scrapped within a few years of its end.
The Amagi class was a series of four battlecruisers planned for the Imperial Japanese Navy (IJN) as part of the Eight-eight fleet in the early 1920s. The ships were to be named Amagi, Akagi, Atago, and Takao. The Amagi design was essentially a lengthened version of the Tosa-class battleship, but with a thinner armored belt and deck, a more powerful propulsion system, and a modified secondary armament arrangement. They were to have carried the same main battery of ten 41 cm (16.1 in) guns and been capable of a top speed of 30 knots.
The Lexington-class battlecruisers were officially the only class of battlecruiser to ever be ordered by the United States Navy. While these six vessels were requested in 1911 as a reaction to the building by Japan of the Kongō class, the potential use for them in the U.S. Navy came from a series of studies by the Naval War College which stretched over several years and predated the existence of the first battlecruiser, HMS Invincible. The fact they were not approved by Congress at the time of their initial request was due to political, not military considerations.
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.
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