The Zara class was a group of four heavy cruisers built for the Italian Regia Marina in the late 1920s and the early 1930s. The class comprised the vessels Zara, Fiume and Pola, the last of, completed to a different design; the ships were a substantial improvement over the preceding Trento-class cruisers, incorporating heavier armor protection at the cost of the high speed of the Trentos. They had a maximum speed of 32 knots. Among the best-protected heavy cruisers built by any navy in the 1930s, the heavy armor was acquired only by violating the terms of the Washington Naval Treaty, which limited cruiser displacement to 10,000 long tons. All four ships served with the main fleet in the interwar period, where they were occupied with training exercises and fleet reviews. During the Spanish Civil War, Gorizia evacuated Italian nationals and Pola took part in non-intervention patrols. All four ships supported the Italian invasion of Albania in April 1939, shortly before the outbreak of World War II.
After Italy joined the wider conflict in 1940, the four ships saw extensive action in the Mediterranean Sea against British forces. The ships took part in the battles of Calabria and Cape Matapan, in the latter engagement, Zara and Fiume were all sunk in a one-sided night action with three British battleships. Gorizia continued in service, seeing further action at the Second Battles of Sirte, she was damaged by American heavy bombers in April 1943 and towed to La Spezia, where she was still under repair when Italy surrendered in September. Germany seized the ship when they occupied the port, Italian commandos unsuccessfully attempted to sink her in June 1944. In poor condition by the end of the war, the postwar Italian Navy decided to sell the ship for scrap in 1947. While the preceding Trento class of heavy cruisers were still being built, elements of the Italian naval command began to doubt the effectiveness of the new vessels, which sacrificed armor protection in favor of high speeds, they advocated a more balanced design that would incorporate more comprehensive armor, with a main belt, 200 millimeters thick, while retaining the battery of eight 203 mm guns and a speed of at least 32 knots.
The designers found that these characteristics could not be incorporated into a vessel that remained within the 10,000 long tons limit imposed by the Washington Naval Treaty. The naval command agreed to allow the new ships to exceed the displacement limits, but instructed the designers to eliminate unnecessary features to save as much weight as possible; as a result, the belt armor was reduced in thickness and the planned torpedo tubes were removed. The flush deck of the Trentos was abandoned, with the ships instead incorporating a forecastle deck and a stepped-down main deck. In addition, the Zara design would be powered by just two propellers driven by lightweight machinery, unlike the four-shaft arrangement used in the Trentos; the ships still exceeded the displacement limit by at least 1,300 long tons. By 1928, the work was finished on what would become the Zara class, the first two ships and Fiume, were ordered for the 1928–1929 building program. Gorizia followed in the 1929–1930 construction year, Pola was ordered under the 1930–1931 program.
All four ships were named for Austro-Hungarian cities that were annexed to Italy in the aftermath of World War I. The ships of the Zara class were 179.6 meters long at 182.8 m long overall. They had a beam of 20.62 m and a draft of 7.2 m. The ships had a standard displacement of 11,326 to 11,712 long tons, displaced 13,944 to 14,330 long tons at full load, with Fiume being the lightest of the four and Gorizia the heaviest; the first three ships were built with light superstructures as a weight saving measure, but Pola, intended to serve as a flagship, received a much larger bridge structure to accommodate an admiral's staff. All four ships received two tripod masts, with the forward mast erected over the bridge, they enlisted men. The ships carried a pair of IMAM Ro.43 seaplanes for aerial reconnaissance. The ships' power plant consisted of two Parsons steam turbines powered by eight oil-fired Thornycroft boilers, with the exception of Fiume, which received Yarrow boilers; the boilers were trunked into two funnels amidships.
Their engines were rated at 95,000 shaft horsepower and produced a top speed of 32 knots, though on sea trials all four vessels exceeded those figures, reaching a minimum of 118,000 shp and speeds of 33 to 34 knots. In service, their practical speeds were in the range of 31 to 32 knots; the vessels each carried 2,300 to 2,400 long tons of fuel oil, which allowed them to steam for 4,850 to 5,400 nautical miles at a cruising speed of 16 knots. When operating at maximum speed, their operational radius fell to 1,150 to 1,900 nautical miles, though due to the fact that Italian naval vessels were intended to operate only within the narrow confines of the Mediterranean Sea, their short cruising range was not a significant problem; the Zaras were armed with a main battery of eight 203 mm Mod 29 53-caliber guns in four gun turrets. The turrets were
Italy the Italian Republic, is a country in Southern Europe. Located in the middle of the Mediterranean Sea, Italy shares open land borders with France, Austria and the enclaved microstates San Marino and Vatican City. Italy covers an area of 301,340 km2 and has a temperate seasonal and Mediterranean climate. With around 61 million inhabitants, it is the fourth-most populous EU member state and the most populous country in Southern Europe. Due to its central geographic location in Southern Europe and the Mediterranean, Italy has been home to a myriad of peoples and cultures. In addition to the various ancient peoples dispersed throughout modern-day Italy, the most famous of which being the Indo-European Italics who gave the peninsula its name, beginning from the classical era and Carthaginians founded colonies in insular Italy and Genoa, Greeks established settlements in the so-called Magna Graecia, while Etruscans and Celts inhabited central and northern Italy respectively; the Italic tribe known as the Latins formed the Roman Kingdom in the 8th century BC, which became a republic with a government of the Senate and the People.
The Roman Republic conquered and assimilated its neighbours on the peninsula, in some cases through the establishment of federations, the Republic expanded and conquered parts of Europe, North Africa and the Middle East. By the first century BC, the Roman Empire emerged as the dominant power in the Mediterranean Basin and became the leading cultural and religious centre of Western civilisation, inaugurating the Pax Romana, a period of more than 200 years during which Italy's technology, economy and literature flourished. Italy remained the metropole of the Roman Empire; the legacy of the Roman Empire endured its fall and can be observed in the global distribution of culture, governments and the Latin script. During the Early Middle Ages, Italy endured sociopolitical collapse and barbarian invasions, but by the 11th century, numerous rival city-states and maritime republics in the northern and central regions of Italy, rose to great prosperity through shipping and banking, laying the groundwork for modern capitalism.
These independent statelets served as Europe's main trading hubs with Asia and the Near East enjoying a greater degree of democracy than the larger feudal monarchies that were consolidating throughout Europe. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science and art. Italian culture flourished, producing famous scholars and polymaths such as Michelangelo, Leonardo da Vinci, Raphael and Machiavelli. During the Middle Ages, Italian explorers such as Marco Polo, Christopher Columbus, Amerigo Vespucci, John Cabot and Giovanni da Verrazzano discovered new routes to the Far East and the New World, helping to usher in the European Age of Discovery. Italy's commercial and political power waned with the opening of trade routes that bypassed the Mediterranean. Centuries of infighting between the Italian city-states, such as the Italian Wars of the 15th and 16th centuries, left the region fragmented, it was subsequently conquered and further divided by European powers such as France and Austria.
By the mid-19th century, rising Italian nationalism and calls for independence from foreign control led to a period of revolutionary political upheaval. After centuries of foreign domination and political division, Italy was entirely unified in 1871, establishing the Kingdom of Italy as a great power. From the late 19th century to the early 20th century, Italy industrialised, namely in the north, acquired a colonial empire, while the south remained impoverished and excluded from industrialisation, fuelling a large and influential diaspora. Despite being one of the main victors in World War I, Italy entered a period of economic crisis and social turmoil, leading to the rise of a fascist dictatorship in 1922. Participation in World War II on the Axis side ended in military defeat, economic destruction and the Italian Civil War. Following the liberation of Italy and the rise of the resistance, the country abolished the monarchy, reinstated democracy, enjoyed a prolonged economic boom and, despite periods of sociopolitical turmoil became a developed country.
Today, Italy is considered to be one of the world's most culturally and economically advanced countries, with the sixth-largest worldwide national wealth. Its advanced economy ranks eighth-largest in the world and third in the Eurozone by nominal GDP. Italy owns the third-largest central bank gold reserve, it has a high level of human development, it stands among the top countries for life expectancy. The country plays a prominent role in regional and global economic, military and diplomatic affairs. Italy is a founding and leading member of the European Union and a member of numerous international institutions, including the UN, NATO, the OECD, the OSCE, the WTO, the G7, the G20, the Union for the Mediterranean, the Council of Europe, Uniting for Consensus, the Schengen Area and many more; as a reflection
Grumman J2F Duck
The Grumman J2F Duck was an American single-engine amphibious biplane. It was used by each major branch of the U. S. armed forces from the mid-1930s until just after World War II for utility and air-sea rescue duties. It was used by the Argentine Navy, who took delivery of their first Duck in 1937. After the war, J2F Ducks saw service with independent civilian operators, as well as the armed forces of Colombia and Mexico; the J2F was an improved version of the earlier JF Duck, with its main difference being a longer float. The J2F-1 Duck first flew on 2 April 1936, powered by a 750 hp Wright R-1820 Cyclone, was delivered to the U. S. Navy on the same day; the J2F-2 had a Wright Cyclone engine, boosted to 790 hp. Twenty J2F-3 variants were built in 1939 for use by the Navy as executive transports with plush interiors. Due to pressure of work following the United States entry into the war in 1941, production of the J2F Duck was transferred to the Columbia Aircraft Corp of New York, they produced 330 aircraft for the Navy and U.
S. Coast Guard. If standard Navy nomenclature practice had been followed, these would have been designated JL-1s, but it was not, all Columbia-produced airframes were delivered as J2F-6s. Several surplus Navy Ducks were converted for use by the United States Air Force in the air-sea rescue role as the OA-12 in 1948; the J2F was an equal-span single-bay biplane with a large monocoque central float which housed the retractable main landing gear, a similar design to the Leroy Grumman-designed landing gear first used for Grover Loening's early amphibious biplane designs, adopted for the Grumman FF fighter biplane. The aircraft had strut-mounted stabilizer floats beneath each lower wing. A crew of two or three were carried in tandem cockpits, forward for the pilot and rear for an observer with room for a radio operator if required, it had a cabin in the fuselage for a stretcher. The Duck's main pontoon was blended into the fuselage, making it a flying boat despite its similarity to a conventional landplane, float-equipped.
This configuration was shared with the earlier Loening OL, Grumman having acquired the rights to Loening's hull and undercarriage designs. Like the F4F Wildcat, its narrow-tracked landing gear was hand-cranked; the J2F was used by the U. S. Navy, Army Air Forces and Coast Guard. Apart from general utility and light transport duties, its missions included mapping, scouting/observation, anti-submarine patrol, air-sea rescue work, photographic surveys and reconnaissance, target tug. J2Fs of the utility squadron of US Patrol Wing 10 were destroyed at Mariveles Bay, Philippines, by a Japanese air raid on 5 January 1942; the only Duck to survive the attack had a dead engine but had been concealed at Cabcaben airfield during the Battle of Bataan, to be repaired afterwards with a cylinder removed from a destroyed J2F-4 submerged in Manila Bay. Following repairs the J2F-4 departed after midnight on 9 April 1942, overloaded with five passengers and the pilot, becoming the last aircraft to depart Bataan before the surrender of the Bataan to the Japanese only hours later.
Among its passengers was Carlos P. Romulo, who recounted the flight in his 1942 best-selling book I Saw the Fall of the Philippines, for which he received the Pulitzer Prize for Correspondence. J2F-1 Initial production version with 750 hp R-1820-20 engines, 29 built. J2F-2 United States Marine Corps version with nose and dorsal guns and underwing bomb racks, 21 built. J2F-2A As J2F-2 with minor changes for use in the United States Virgin Islands, nine built. J2F-3 J2F-2 but powered by an 850 hp R-1820-26 engine, 20 built. J2F-4 J2F-2 but powered by an 850 hp R-1820-30 engine and fitted with target towing equipment, 32 built. J2F-5 J2F-2 but powered by a 1,050 hp R-1820-54 engine, 144 built. J2F-6 Columbia Aircraft built version of the J2F-5 with a 1,050 hp R-1820-64 engine in a long-chord cowling, fitted with underwing bomb racks and provision for target towing gear. OA-12 Air-sea rescue conversion for the United States Army Air Forces. ArgentinaArgentine Naval Aviation received four new-build Grumman G-15s in 1939, to supplement the eight Grumman G-20s received in 1937.
In 1946–1947, 32 ex-US Navy Ducks were acquired, with the last examples remaining in use until 1958. ColombiaColombian Navy. MexicoMexican Navy. PeruPeruvian Navy. United StatesUnited States Army Air Forces United States Coast Guard United States Marine Corps United States Navy The United States Coast Guard worked with North South Polar, Inc. to recover a J2F-4 Duck, serial number V-1640, downed in a storm on a Greenland glacier on 29 November 1942. Two Coast Guard airmen were lost along with a rescued U. S. Army Air Forces passenger from a downed B-17 searching for a downed C-53 with five on board; the three men of the Duck are presumed to still be entombed at the site. North South Polar, under the auspices of the Coast Guard team, located the aircraft in August 2012 resting 38 feet beneath the surface of the ice sheet; as per the mandate of Title 10 of the U. S. Code, North South Polar, the Coast Guard and the Joint POW/MIA Accounting Command plan to recover the men's remains for proper interment.
The Coast Guard and North South Polar are developing plans to recover the aircraft and restore it to flying condition as a memorial to the aircrew. Noted aviatio
A conning tower is a raised platform on a ship or submarine armored, from which an officer in charge can conn the vessel, controlling movements of the ship by giving orders to those responsible for the ship's engine, rudder and ground tackle. It is located as high on the ship as practical, to give the conning team good visibility of the entirety of the ship, ocean conditions, other vessels; the verb "conn" stems from the verb "conduct" rather than another plausible precedent, the verb "control". On surface ships, the conning tower was a feature of all battleships and armored cruisers from about 1860 to the early years of World War II. Located at the front end of the superstructure, the conning tower was a armored cylinder, with tiny slit windows on three sides providing a reasonable field of view. Designed to shield just enough personnel and devices for navigation during battles, its interior was cramped and basic, with little more than engine order telegraphs, speaking tubes or telephones, a steering wheel.
At all other times than during battles, the ship would be navigated from the bridge. Conning towers were used by the French on their floating batteries at the Battle of Kinburn, they were fitted to the first ironclad the French battleship La Gloire. The first Royal Navy conning tower appeared on HMS Warrior. In the Royal Navy, the conning tower became a massive structure reaching weights of hundreds of tons on the Admiral-class battlecruisers, formed part of a massive armoured citadel on the mid-1920s Nelson-class battleships, which had armour over a foot thick; the King George V class, in contrast to the Nelson class, had comparatively light conning tower protection with 4.5-inch sides, 3-inch front and rear, 2-inch roof and deck. The RN's analysis of World War I combat revealed that command personnel were unlikely to use an armoured conning tower, preferring the superior visibility of unarmoured bridge positions. Older RN battleships that were reconstructed with new superstructures had their armoured conning towers removed and replaced with much lighter structures.
These new conning towers were placed much higher in the ship, for superior visibility. There is no evidence that RN captains and admirals used the armoured conning towers on those ships that did have them during World War II, for example, Vice-Admiral Holland and Captain Kerr commanding Hood during the Battle of the Denmark Strait from her unarmoured bridge. In the United States Navy, battleship captains and admirals preferred to use the unarmoured bridge positions during combat; the USN had mixed opinions of the conning tower, pointing out that its weight, high above the ship's center of gravity, did not contribute directly to fighting ability. Beginning in the late 1930s, as radar surpassed visual sighting as the primary method of detecting other ships, battleships began reducing or eliminating the conning tower; the battle of Guadalcanal during World War II slowed this trend: when the Japanese battleship Kirishima hit USS South Dakota on the superstructure, many exposed crewmen were killed or wounded yet Admiral Lee and Captain Davis of USS Washington declined to use the armoured conning tower during the battle.
Soon the heavy battleship conning towers were removed from USS Pennsylvania, USS Tennessee, USS California, USS West Virginia during their post-Pearl Harbor attack reconstructions and replaced with much lighter cruiser-style conning towers. By the end of World War II, US ships were designed with expanded weather bridges enclosing the armored conning towers. On Iowa-class battleships, the conning tower is a 17.3-inch thick vertical armor-plated cylinder with slit windows located in the middle of the bridge, climbing from deck 03 all the way up to the flying bridge on 05. With the demise of battleships after World War II, along with the advent of missiles and nuclear weapons during the Cold War, modern warships no longer feature conning towers; the conning tower of a submarine was a small watertight compartment within its sail equipped with instruments and controls and from which the periscopes were used to direct the boat and launch torpedo attacks. It should not be confused with the submarine's control room, directly below it in the main pressure hull.
As improvements in technology allowed the periscopes to be made longer it became unnecessary to raise the conning station above the main pressure hull. USS Triton was the last American submarine to have a conning tower; the additional conning tower pressure hull was eliminated and its functions were added to the command and control center. Thus it is incorrect to refer to the sail of a modern submarine as a conning tower. "Conning Tower". The New Student's Reference Work. 1914
Veinticinco de Mayo-class cruiser
The two Veinticinco de Mayo-class heavy cruisers served in the Argentine Navy through World War II. They were the only post-Washington Naval Treaty heavy cruisers built for a South American Navy. Both ships of the class were built in Italy by the OTO company, commissioned into the Argentine Navy in 1931; the Veinticinco de Mayo design was derived from the Italian Trento class, identifiable by the paired main guns, similar to the last batches of the Condottieri-class cruisers. The ships were smaller than the original, carried less armour, they had a clean and simple design, with a length-width ratio of 10:1. Three twin turrets were mounted with an elevation of 46 degrees for firing, they were not the first Argentinian cruiser class bought in Italy, as four Giuseppe Garibaldi-class armoured cruisers were brought into service 30 years before. The main 190 mm guns were designed for this class for greater stability; this could have been a quite powerful gun, but no documents about its characteristics are available in Italian or Argentinian archives.
The guns had single mounts to simplify construction, could fire a 90 kg shell up to 23 kilometres. Despite this reduction in size and weight, they were still too heavy, so the number of turrets were reduced from four to three. In most respects the resulting vessel was similar in profile to the British York class; the secondary armament was a new design, similar to standard 100–102 mm guns of the time. It consisted of twelve 102 mm /45 DP guns, firing a 13.5 kg shell, all in twin mounts. This was an unusual arrangement for Italian heavy cruisers, which carried sixteen of these weapons; however to counter the additional weight, gun shields were removed, which adversely affected their operability in bad weather conditions. Unusually, the torpedo tubes were in fixed mounts amidships firing abeam, which caused problems in aiming effectively. Light anti-aircraft artillery consisted of six Vickers-Terni 40/39 mm guns, all in single mounts, on the aft part of the superstructure; these guns were among the first automatic heavy weapons, firing 100-130 rounds per minute, but were of poor reliability.
Though single mounts were simpler and more reliable, they offered poorer fire concentration. The Royal Navy used similar weapons in quad or octuple mounts. A catapult launcher for seaplanes was placed over the fore deck. Armour was within the standard for light rather than heavy cruisers. A 70 mm armoured belt was fitted from the first to the last main turret. 60 mm was used for the command turret. 50 mm was used for barbettes. Only 25 mm was provided above aft machinery. After World War II the ships were modified to improve their stability by reducing weight; the powerful twin 102 mm gun batteries were replaced with six Bofors 40 mm guns, one for each twin mount, drastically reducing the secondary armament. Another four Bofors replaced the six Vickers AA guns. US Mk.53 radar directors were installed to improve the effectiveness of anti-aircraft fire. The gain in stability, with several tons removed for each 102 mm gun, was somewhat offset by the addition of radar installations to the superstructure and masts.
The aircraft catapult. Despite Argentina's declaration of war on 27 March 1945, neither vessel played a role in the conflict; the ships proved popular with the Argentine Navy, until they were superseded by two Brooklyn-class cruisers acquired in 1951. Named after the 25th of May, Argentina's National Day. Built by OTO La Foce, laid down 12 October 1927, launched 28 September 1929, completed 18 July 1931. Decommissioned 27 June 1961. Named after Admiral Guillermo Brown, father of the Argentine Navy. Built by OTO Livorno, laid down 27 November 1927, launched 11 August 1929, completed 11 July 1931. Decommissioned 27 June 1961. Argentina planned to acquire three of the class, but were limited to having only two built, they would turn to the United Kingdom for their next cruiser, acquiring La Argentina in 1938. List of cruisers List of World War II ships List of ship commissionings in 1931 M. J Whitley, Cruisers of World War II, An International Encyclopedia Arms and Armour Press Article in "Storia Militare" magazine, October 2007.
Burzaco, Ricardo. Acorazados y Cruceros de la Armada Argentina. Eugenio B, Buenos Aires, 1997. ISBN 987-96764-0-8 Arguindeguy, Pablo. Apuntes sobre los buques de la Armada Argentina. Comando en Jefe de la Armada, Buenos aires, 1972. ISBN n/d History of argentinian cruisers, at HISTARMAR
A sister ship is a ship of the same class or of identical design to another ship. Such vessels share a nearly identical hull and superstructure layout, similar size, comparable features and equipment, they share a common naming theme, either being named after the same type of thing or with some kind of alliteration. Sisters become more differentiated during their service as their equipment are separately altered. For instance, the U. S. warships USS Iowa, USS New Jersey, USS Missouri, USS Wisconsin are all sister ships, each being an Iowa-class battleship. The most famous sister ships were RMS Titanic and HMHS Britannic; as with some other liners, the sisters worked as running mates. Other sister ships include the Royal Caribbean International's Explorer of the Seas and Adventure of the Seas. Half-sister refers with some significant differences. One example of half-sisters are the First World War-era British Courageous-class battlecruisers where the first two ships had four 15-inch guns, but the last ship, HMS Furious, had two 18-inch guns instead.
Another example is the American Essex-class aircraft carriers of the Second World War that came in "long-hull" and "short-hull" versions. Notable airships include the American sister ships USS Akron and USS Macon, the German Hindenburg class airship's Hindenburg and Graf Zeppelin II; the accepted commercial distinctions of a sister ship are the following: Type: Identical main type Dry weight: ± 10% on the DWT Builder: Identical shipbuilding company name The critical overriding criteria are the same hull design. For example, the popular TESS-57 standard design built by Tsunishi Shipbuilding are built in Japan and the Philippines. All the ships of this design are classed as sister ships; the International Maritime Organization defined sister ship in IMO resolution MSC/Circ.1158 in 2006. Criteria included these: A sister ship is a ship built by the same yard from the same plans; the acceptable deviation of lightship displacement should be between 1 and 2% of the lightship displacement of the lead ship, depending on the length of the ship.
Ship naming and launching Ship commissioning
The Hawkins class was a class of five heavy cruisers of the Royal Navy designed in 1915 and constructed throughout the First World War. All ships were named after Elizabethan sea captains; the three ships remaining as cruisers in 1939 served in the Second World War, with Effingham being an early war loss through wreck. Vindictive, though no longer a cruiser served throughout the War; this class formed the basis for the definition of the maximum cruiser type under the Washington Naval Treaty of 1922. Although the Hawkins class were the first heavy cruisers built for the Royal Navy, they were designed as improved versions of the Birmingham sub-class of the Town-class light cruisers, thus they were known as the "Improved Birmingham" type, their lineage descended through an intermediate sketch design of 1912 known as the "Atlantic Cruiser", armed with a combination of 7.5 and 6-inch guns, designed to counter reported large German cruisers armed with 7-inch guns. In 1915, a new design of cruiser was prepared for trade protection on distant waters, for which a heavy armament, long range and high speed was required.
Previous large cruisers had been of protected cruiser type. These ships had been made obsolete by the adoption of oil-firing and the steam turbine engine and had been superseded by the battlecruiser and the light cruiser; the Hawkins design was a light cruiser enlarged sufficiently to increase their range and armament as required. A mixed armament of 9.2 and 6-inch guns was rejected after wartime experience illustrated the difficulty of controlling a mixed battery as shell splashes could not be differentiated. Thus, a uniform battery of 7.5-inch calibre was adopted, controlled by the innovation of director firing. The development of director firing made the planned armament obsolete, as director control relies on "straddles" in which some shells in a given salvo are seen to fall short of the target and some long; as long as straddles are maintained, some percentage of the shots will be hits. With a main battery consisting of only two guns, a straddle of one shell falling short and one long mathematically eliminates the possibility of a hit, while a uniform six-gun broadside allows the possibility of up to four hits out of a straddle.
The boilers were a combination of coal and oil firing to ensure a supply of fuel on distant stations. The installed power was 60,000 shp for 30 knots. However, only Hawkins and Vindictive were completed as such; the other ships were not constructed with as much haste and were completed post-war with oil-firing only, increasing power to 70,000 shp for 31 knots. These ships did not suit the Royal Navy's post-World War I needs well, as Britain needed numbers of cruisers, rather than individually powerful ships; as breaking them up on the slips would have been an unwarranted waste of money, they were completed anyway. At just under 10,000 tons and armed with 7.5-inch guns, they became the prototype of the heavy cruiser designs based on limitations set by the Washington Naval Treaty in 1922. The fifth and last ship of the class - laid down as Cavendish - was altered to an aircraft carrier while building, renamed Vindictive to perpetuate the name of the cruiser sunk at the Second Ostend Raid and her construction was rushed to bring her into service before her cruiser sisters.
She had a 100-foot flying-off platform forwards and a 215-foot landing deck aft and a hangar for up to eight aircraft. She was armed with six 12-pounder guns. In 1923 she reverted to a cruiser, but did not carry a ` B' gun. After 1935 she did not serve in a cruiser role. No ships were completed with the original design secondary armament. Hawkins carried only the 12-pounder anti-aircraft guns, her sisters having two or three QF 4-inch Mark V guns on mountings HA Mark III. In 1929, Hawkins had her 12-pounder guns replaced by an equal number of the same model of 4-inch guns as her sisters. Frobisher was disarmed as a training ship in 1932, but reverted to a cruiser in 1937 when Vindictive was specially demilitarised for this role; the ships were scheduled for disposal in 1936, but rising international tensions caused their retention. In 1937, Effingham was rebuilt as a light cruiser with nine BL 6-inch Mark XII guns on single mountings CP Mark XIV; these were shipped superfiring forwards in'A','B' and'C' positions, on either wing, triple aft in'W','X' and'Y' positions with the ninth gun being on the quarterdeck in position'Z'.
The after boiler rooms were removed and the remaining uptakes trunked into a single large funnel. Secondary armament was eight QF 4-inch Mark XVI on twin mountings HA/LA Mark XIX, eight QF 2-pounder Mark VIII guns on two quadruple mountings Mark VII and twelve 0.5 inch Vickers machine guns on three quadruple mountings Mark I. The submerged torpedo tubes were removed, she carried a crane amidships. It had been planned to rebuild Hawkins and Frobisher on similar lines, but other priorities prevented this, they were re-armed for war with all their 7.5-inch guns, except in Frobisher which had the wing guns removed so that the 4-inch gun deck could be extended out to the ship's sides. In 1940, they received two or four quadruple 2 pounder "multiple pom-pom" mountings and seven or eight 20 mm Oerl