G3 battlecruiser
Encyclopedia
The G3 battlecruisers were a class
of battlecruiser
s planned by the Royal Navy
after the end of World War I
in response to naval expansion programs by the United States
and Japan
. The four ships of this class would have been larger, faster and more heavily-armed than any existing battleship (although several projected foreign ships would be larger). The "battlecruiser" designation came from their higher speed and lesser firepower and armour relative to the planned N3 class battleship
design. The G3s carried nine 16 inches (406.4 mm) guns and were expected to achieve 32 knots, while the N3s would carry nine 18 inches (457.2 mm) guns on the same displacement at the expense of a slower speed. While officially referred to as "battlecruisers", the G3s have also been considered "fast battleship
s".
The G3 design was approved by the Board of Admiralty on 12 August 1921. Orders were placed in October—November, but were suspended later in November with the beginning of the Washington Naval Conference
which limited battleship numbers. The orders were cancelled in February 1922 with the ratification of the Washington Naval Treaty
which limited construction to ships of no more than 35000 long tons (35,561.8 t) displacement.
in 1916. Three of this class were cancelled, leaving only to be completed to an altered design.
The US plan had been delayed by the wartime need to build smaller vessels. Nevertheless, estimates by the Admiralty were that by the early 1920s the UK would be behind in ships. The British did have access to German technology through ships such as the battleship which had been saved from the scuttling of the interned German
High Seas Fleet
in Scapa Flow
and the experiences of the war. A committee concluded that any new ship should be able to match the speed of the new US s, expected to make 32 knots. Consequently a series of designs was prepared of ships with displacements ranging from 53100 to 44500 LT (53,952.3 to 45,214.2 t), the only limitations being the ability to use British dockyards and passage through the Suez Canal
. These designs were given letters of the alphabet running backwards from K to G. The related battleship designs under consideration at the same time had design letters from L upwards.
The first two design proposals, 'K2' and 'K3', had a general layout similar to Hood, but were armed with either eight or nine 18-inch guns, in four twin or three triple gun turret
s, respectively. The numeral in the designation came from the number of guns in each turret. These ships were very large, displacing 52000 to 53100 LT (52,834.6 to 53,952.3 t), could only reach 30 knots (16.3 m/s), and could only be docked in a single ex-German floating dock
and one dock in Liverpool
. 'J3', the next proposal, saved nearly 10000 long tons (10,160.5 t) by reducing the main armament to nine 50-calibre
15 inches (381 mm) guns and the main deck armour to 4 inches (10 cm). This reduction in size allowed the ship to dock anywhere that Hood could dock and to pass through the Suez and Panama Canal
s. 'I3' took another route in saving weight and concentrated the main armament amidships with 'X' turret placed between the forward superstructure and the funnels. The consequent weight savings were negated by additional hull and machinery weights and the ship displaced only slightly less than 'K3'. It had the advantage, however, that it could be docked in Rosyth
and Portsmouth
and pass through both canals, once the Suez Canal had been deepened. The primary drawback was that the main armament had a blind spot towards the rear of the ship of no less than 40°. Several variations were evaluated of the 'H3' design with the number of turrets reduced. In 'H3a' both turrets were forward of the superstructure while in 'H3b' one was forward and the other was aft of the forward superstructure. 'H3c' retained the layout of 'H3b', but lowered the turrets by one deck and saved 1250 long tons (1,270.1 t) over the 45000 long tons (45,722.3 t) of 'H3b'. All three 'H3' designs had a maximum speed of 33 knots (18 m/s), but the reduced number of main guns was disliked so the 'G3' was proposed with the three triple turrets, armed with 16.5 inches (42 cm) guns to save weight.
This design was accepted at the end of 1920, but changes were made as the design was finalized in early 1921, including the reduction of the ship's horsepower from 180,000 to 160,000 and the reduction of the main armament from 16.5 inches to 16 inches (41 cm).
-era capital ships, or at least for British designs of this type. Most immediately noticeable was the concentration of the main battery forward of the bridge and engineering spaces, giving the ships a tanker-like appearance. Since the G3s were to use existing dockyard facilities, this layout allowed designers to keep the length of the ships, as well as the weight of armour, to a minimum. The resulting loss of heavy fire astern was considered justifiable since the ships were intended to fight on the broadside. A related feature of the G3 and N3 designs was their tower bridge structure behind the first two gun turrets. This provided a better and more stable foundation for fire-control equipment, greatly improved accommodation and protection from the weather.
of 106 feet (32.3 m), and a draught of 36 feet (11 m) at deep load. They would have displaced 48400 long tons (49,176.8 MT) normally and 53909 long tons (54,774.2 MT) at deep load, over 8000 long tons (8,128.4 MT) more than the older ships. They had a metacentric height
of 7.786 feet (2.4 m) at deep load as well as a complete double bottom
.
sets, each of which drove one propeller shaft. They were arranged in three engine rooms. The forward engine room held the two turbines for the wing shafts, the middle compartment housed the turbine for the port inner shaft and the aft engine room contained the turbine for the starboard inner shaft. The turbines were powered by 20 Yarrow
small-tube boilers
divided between nine boiler rooms. They were designed to produce a total of 160000 shp at a working pressure of 200 psi (1,378,951 Pa) and temperature of 200 °F (93.3 °C). Maximum speed would have been 32 knots (17.4 m/s)
The ships had a maximum capacity of 5000 long tons (5,080.3 t) of fuel oil
. Using the 22000 shp cruising turbines, they had an estimated maximum range of 7000 nautical miles (12,964 km) at 16 knots (8.7 m/s). They had six turbo-driven 250 kW dynamo
s and two 300 kW Diesel generator
s.
length which were lower-muzzle-velocity weapons firing heavy shells.
The G3 design mounted nine BL 16-inch Mark I 45-calibre guns in three triple hydraulically powered Mark I gun turret
s, designated 'A', 'B', and 'X' from front to rear. The guns could be depressed to −3° and elevated to 40°. The ships' maximum stowage was 116 shells per gun. They fired 2048 pounds (929 kg) projectiles at a muzzle velocity
of 2670 ft/s (813.8 m/s). Their maximum range was about 38000 yards (34,747.2 m) at maximum elevation. The G3s carried a secondary armament of sixteen BL 6-inch Mark XXII guns
in superfiring
twin turrets instead of casemates—the first time in a British capital ship since the of 1904. Four turrets were sited around the forward superstructure and four at the stern. The forward turrets were provided with 150 rounds per gun and the rear turrets with 110 rounds per gun. The guns could elevate between –5° and +60°. They fired 100 pounds (45.4 kg) projectiles at a muzzle velocity of 2945 ft/s (897.6 m/s). Their maximum range was 25800 yd (23,591.5 m) at 45° elevation. Their rate of fire was five rounds per minute.
An anti-aircraft
battery of six QF 4.7-inch Mark VIII guns
was included. They had a maximum depression of -5° and a maximum elevation of 90°. They fired a 50 pounds (22.7 kg) high explosive shell at a muzzle velocity of 2457 ft/s (748.9 m/s) at a rate of eight to twelve rounds per minute. The guns had a maximum ceiling of 32000 ft (9,753.6 m), but an effective range of much less. A maximum of 256 rounds per could be carried. The ships were intended to carry four 8-barreled mountings for the 40 millimetres (1.6 in) QF 2-pounder Mark VIII gun
(commonly known as a pom-pom), two abaft the funnels and two at the stern. Each barrel was provided with 1300 rounds of ammunition. The gun fired a 40 millimetres (1.6 in) 2 pound (0.90718474 kg) shell at a muzzle velocity of 1920 ft/s (585.2 m/s) to a distance of 3800 yards (3,474.7 m). The gun's rate of fire was approximately 96–98 rounds per minute.
Like previous classes of British battlecruisers, a pair of submerged, broadside-firing torpedo tube
s were planned for these ships. Their compartment was located just forward of the 'A' shell room on the platform deck. Six 24.5 inches (62.2 cm) torpedoes per tube were to be carried in peace-time, but this would increase to eight in wartime. These Mark I torpedoes had a warhead of 743 pounds (337 kg) of TNT and were powered by oxygen-enriched air. They had two speed settings which governed their range: either 15000 yards (13,716 m) at 35 knots (19.1 m/s), or 20000 yards (18,288 m) at 30 knots (16.3 m/s).
in an armoured hood and the third was aft. Each main gun turret was provided with a 41 feet (12.5 m) coincidence rangefinder
in an armoured housing on the turret roof. The secondary armament was primarily controlled by three DCTs. Two mounted on each side of the bridge and the third was aft. The anti-aircraft guns were controlled by a high-angle control system mounted on the very top of the forward superstructure. Each pom-pom mount had its own director and there was also a height-finder aft. Two 15 feet (4.6 m) torpedo rangefinders were located on the sides of the funnels.
was the use of the all or nothing protection scheme in the G3s. Medium-thickness armour had proven to be useless in stopping heavy-calibre shells during World War I so the vital areas of the ship were protected by the thickest possible armour and the rest of the ship was left unarmoured. Use of this system was pioneered by contemporary U.S. Navy battleship designs starting with the . However, this system of protection required that the armoured citadel should have enough reserve buoyancy to keep the ship stable even if the rest of the hull was riddled by gunfire.
The waterline belt
of the G3 had a maximum thickness of 14 inches (36 cm) with the top of the armour angled 18° outwards. This angle increased the armor's relative thickness to horizontal, close-range fire, albeit at the cost of reducing its relative height which increased the chance of plunging shellfire going over or under it. It ran some 522 feet (159.1 m), from the forward edge of 'A' barbette to the rear of the after 6-inch magazine. The belt had a height of 14 in 3 in (4.34 m), which 4 in 6 in (1.37 m) was below the designed waterline. Only the forward 259 feet (78.9 m) of the belt had the maximum thickness, it thinned to 12 inches (30 cm) for the rest of its length. The lower edge of the belt abreast the magazines was continued down another 3 foot (0.9144 m) by a 4 inches (10.2 cm) thickness of high-tensile steel inclined at 36° to prevent a shell from reaching the magazines via a wave trough at high speed. The forward and rear ends of the belt terminated in 12-inch and 10 inches (25 cm) tranverse bulkhead
s respectively. The waterline belt extended forward 46 feet (14 m) at a thickness of 6 inches that reduced to 2.25 inches (5.7 cm) in two steps.
The funnel and boiler room ventilation shafts were surrounded by an armoured box 116 feet (35.4 m) long intended to prevent shells fired from behind the ship reaching 'X' magazine. The box narrowed at an angle of 21° as it rose and had a maximum thickness of 12 inches nearest to the magazine. Aft it reduced in a series of steps to 9 inches (23 cm), 6 inches, 5 inches (13 cm) and 4 inches (10 cm). The armoured deck matched the length of the waterline belt and sloped down 2.5° to meet the upper edge of the belt. It had a maximum thickness of 8 inches (20 cm) from the 'A' barbette to partway over the mid-boiler rooms and thinned to a minimum of 4 inches over the rear engine and boiler rooms. The deck's thickness increased to 7 inches (17.8 cm) partway over the rear engine room and covered the aft 6-inch magazines. The armoured deck extended forward 46 feet over the torpedo compartment with a maximum thickness of 8 inches, thinning to 6 inches. The armoured deck's rear extension was 106 inch long and was 5 inches thick until the last 27 inch when it thinned to 3 inches (8 cm).
The turret faces were 17.5 inches (44 cm) thick while their sides ranged from 9 to 13 in (22.9 to 33 ) in thickness, and the roof was 8 inches thick. The armour of the barbettes ranged from 11 to 14 in (27.9 to 35.6 ) in thickness and it was carefully arranged to minimize the likely risk. The conning tower
armour was 9 to 12 inches thick and its communications tube to the upper deck was 8 inches thick. The fire-control director atop the conning tower was protected by an armoured hood 3 to 5 inches thick.
The anti-torpedo bulge
s of the G3 battlecruisers were intended to withstand the explosion of a 750 pounds (340.2 kg) torpedo warhead
. They consisted of an outer air space, an inner buoyancy space and the torpedo bulkhead
that consisted of two layers of 0.875 inches (2 cm) high-tensile steel. The bulkhead was situated some 13.5 feet (4.1 m) inboard from the side of the ship. Postwar tests done on a replica of this system showed that filling the buoyancy space with water rather than the sealed steel crushing tubes as used in was just as effective and weighed less. A compressed air system was fitted to blow the water out of the buoyancy spaces and bring the ship upright in 15 minutes after two torpedo hits. The ship's double bottom
ranged from 5–7 ft (1.5–2.1 ) in depth.
, an arms limitation
treaty under negotiation at the time, led to the suspension of building on 18 November 1921 and outright cancellation in February 1922 because the treaty forbade construction of any ship larger than 35000 long tons (35,561.8 t). Although the ships were ordered, none were actually laid down.
Many of the aspects of their design ultimately were incorporated into the two s, and they are often described as being a cut-down G3. Indeed, the Nelsons received the design designation 'O3', marking them as next in the design sequence from the 'N3' battleship design although they used the guns intended for the G3 class for cost reasons and to comply with the Treaty's 16-inch limitation on main armament.
Ship class
A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....
of battlecruiser
Battlecruiser
Battlecruisers were large capital ships built in the first half of the 20th century. They were developed in the first decade of the century as the successor to the armoured cruiser, but their evolution was more closely linked to that of the dreadnought battleship...
s planned by the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
after the end of World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
in response to naval expansion programs by the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The four ships of this class would have been larger, faster and more heavily-armed than any existing battleship (although several projected foreign ships would be larger). The "battlecruiser" designation came from their higher speed and lesser firepower and armour relative to the planned N3 class battleship
N3 class battleship
The N3 class was a dreadnought battleship class designed for the Royal Navy after World War I, incorporating all the lessons learned from that conflict. They were very similar in design to the s, but had larger guns and thicker armour...
design. The G3s carried nine 16 inches (406.4 mm) guns and were expected to achieve 32 knots, while the N3s would carry nine 18 inches (457.2 mm) guns on the same displacement at the expense of a slower speed. While officially referred to as "battlecruisers", the G3s have also been considered "fast battleship
Fast battleship
Historically, a fast battleship was a battleship which emphasized speed without - in concept - undo compromise of either armor or armament. The term is especially appropriate when applied to a design which was not only faster than the preceding battleship class, but faster than subsequent classes...
s".
The G3 design was approved by the Board of Admiralty on 12 August 1921. Orders were placed in October—November, but were suspended later in November with the beginning of the Washington Naval Conference
Washington Naval Conference
The Washington Naval Conference also called the Washington Arms Conference, was a military conference called by President Warren G. Harding and held in Washington from 12 November 1921 to 6 February 1922. Conducted outside the auspices of the League of Nations, it was attended by nine nations...
which limited battleship numbers. The orders were cancelled in February 1922 with the ratification of the Washington Naval Treaty
Washington Naval Treaty
The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...
which limited construction to ships of no more than 35000 long tons (35,561.8 t) displacement.
Background
In 1916 the US had declared its intention to create a Navy "second to none"; Congress had authorized the building of a large number of battleships and battlecruisers. In the aftermath of the First World War, the Japanese government were also embarking on a large programme of warship building. Meanwhile, in Great Britain, the needs of the First World War had led to the pre-war s being followed by the slower and cheaper s. Two improved Revenge class hulls were converted during construction into the two s as emergency builds during the war. The only new capital ships laid down in the war were the s. Their design had been called into question after the Battle of JutlandBattle of Jutland
The Battle of Jutland was a naval battle between the British Royal Navy's Grand Fleet and the Imperial German Navy's High Seas Fleet during the First World War. The battle was fought on 31 May and 1 June 1916 in the North Sea near Jutland, Denmark. It was the largest naval battle and the only...
in 1916. Three of this class were cancelled, leaving only to be completed to an altered design.
The US plan had been delayed by the wartime need to build smaller vessels. Nevertheless, estimates by the Admiralty were that by the early 1920s the UK would be behind in ships. The British did have access to German technology through ships such as the battleship which had been saved from the scuttling of the interned German
Scuttling of the German fleet in Scapa Flow
The scuttling of the German fleet took place at the Royal Navy's base at Scapa Flow, in Scotland, after the end of the First World War. The High Seas Fleet had been interned there under the terms of the Armistice whilst negotiations took place over the fate of the ships...
High Seas Fleet
High Seas Fleet
The High Seas Fleet was the battle fleet of the German Empire and saw action during World War I. The formation was created in February 1907, when the Home Fleet was renamed as the High Seas Fleet. Admiral Alfred von Tirpitz was the architect of the fleet; he envisioned a force powerful enough to...
in Scapa Flow
Scapa Flow
right|thumb|Scapa Flow viewed from its eastern endScapa Flow is a body of water in the Orkney Islands, Scotland, United Kingdom, sheltered by the islands of Mainland, Graemsay, Burray, South Ronaldsay and Hoy. It is about...
and the experiences of the war. A committee concluded that any new ship should be able to match the speed of the new US s, expected to make 32 knots. Consequently a series of designs was prepared of ships with displacements ranging from 53100 to 44500 LT (53,952.3 to 45,214.2 t), the only limitations being the ability to use British dockyards and passage through the Suez Canal
Suez Canal
The Suez Canal , also known by the nickname "The Highway to India", is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea and the Red Sea. Opened in November 1869 after 10 years of construction work, it allows water transportation between Europe and Asia without navigation...
. These designs were given letters of the alphabet running backwards from K to G. The related battleship designs under consideration at the same time had design letters from L upwards.
The first two design proposals, 'K2' and 'K3', had a general layout similar to Hood, but were armed with either eight or nine 18-inch guns, in four twin or three triple gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...
s, respectively. The numeral in the designation came from the number of guns in each turret. These ships were very large, displacing 52000 to 53100 LT (52,834.6 to 53,952.3 t), could only reach 30 knots (16.3 m/s), and could only be docked in a single ex-German floating dock
Floating dock
A floating dock is a platform or ramp supported by pontoons. It is usually joined to the shore with a ramp that rests upon the dock on rollers, to adjust for the vertical movement of the dock...
and one dock in Liverpool
Liverpool
Liverpool is a city and metropolitan borough of Merseyside, England, along the eastern side of the Mersey Estuary. It was founded as a borough in 1207 and was granted city status in 1880...
. 'J3', the next proposal, saved nearly 10000 long tons (10,160.5 t) by reducing the main armament to nine 50-calibre
Caliber (artillery)
In artillery, caliber or calibredifference in British English and American English spelling is the internal diameter of a gun barrel, or by extension a relative measure of the length....
15 inches (381 mm) guns and the main deck armour to 4 inches (10 cm). This reduction in size allowed the ship to dock anywhere that Hood could dock and to pass through the Suez and Panama Canal
Panama Canal
The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...
s. 'I3' took another route in saving weight and concentrated the main armament amidships with 'X' turret placed between the forward superstructure and the funnels. The consequent weight savings were negated by additional hull and machinery weights and the ship displaced only slightly less than 'K3'. It had the advantage, however, that it could be docked in Rosyth
Rosyth
Rosyth is a town located on the Firth of Forth, three miles south of the centre of Dunfermline. According to an estimate taken in 2008, the town has a population of 12,790....
and Portsmouth
Portsmouth
Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...
and pass through both canals, once the Suez Canal had been deepened. The primary drawback was that the main armament had a blind spot towards the rear of the ship of no less than 40°. Several variations were evaluated of the 'H3' design with the number of turrets reduced. In 'H3a' both turrets were forward of the superstructure while in 'H3b' one was forward and the other was aft of the forward superstructure. 'H3c' retained the layout of 'H3b', but lowered the turrets by one deck and saved 1250 long tons (1,270.1 t) over the 45000 long tons (45,722.3 t) of 'H3b'. All three 'H3' designs had a maximum speed of 33 knots (18 m/s), but the reduced number of main guns was disliked so the 'G3' was proposed with the three triple turrets, armed with 16.5 inches (42 cm) guns to save weight.
This design was accepted at the end of 1920, but changes were made as the design was finalized in early 1921, including the reduction of the ship's horsepower from 180,000 to 160,000 and the reduction of the main armament from 16.5 inches to 16 inches (41 cm).
Design and description
The G3s incorporated several novel features for dreadnoughtDreadnought
The dreadnought was the predominant type of 20th-century battleship. The first of the kind, the Royal Navy's had such an impact when launched in 1906 that similar battleships built after her were referred to as "dreadnoughts", and earlier battleships became known as pre-dreadnoughts...
-era capital ships, or at least for British designs of this type. Most immediately noticeable was the concentration of the main battery forward of the bridge and engineering spaces, giving the ships a tanker-like appearance. Since the G3s were to use existing dockyard facilities, this layout allowed designers to keep the length of the ships, as well as the weight of armour, to a minimum. The resulting loss of heavy fire astern was considered justifiable since the ships were intended to fight on the broadside. A related feature of the G3 and N3 designs was their tower bridge structure behind the first two gun turrets. This provided a better and more stable foundation for fire-control equipment, greatly improved accommodation and protection from the weather.
General characteristics
The G3 battlecruisers were significantly larger than their predecessors of the . They had an overall length of 856 feet (260.9 m), a beamBeam (nautical)
The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...
of 106 feet (32.3 m), and a draught of 36 feet (11 m) at deep load. They would have displaced 48400 long tons (49,176.8 MT) normally and 53909 long tons (54,774.2 MT) at deep load, over 8000 long tons (8,128.4 MT) more than the older ships. They had a metacentric height
Metacentric height
The metacentric height is a measurement of the static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre . A larger metacentric height implies greater stability against overturning...
of 7.786 feet (2.4 m) at deep load as well as a complete double bottom
Double bottom
A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a...
.
Propulsion
The G3 battlecruisers would have had four geared steam turbineSteam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....
sets, each of which drove one propeller shaft. They were arranged in three engine rooms. The forward engine room held the two turbines for the wing shafts, the middle compartment housed the turbine for the port inner shaft and the aft engine room contained the turbine for the starboard inner shaft. The turbines were powered by 20 Yarrow
Yarrow Shipbuilders
Yarrow Limited , often styled as simply Yarrows, was a major shipbuilding firm based in the Scotstoun district of Glasgow on the River Clyde...
small-tube boilers
Water-tube boiler
A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes...
divided between nine boiler rooms. They were designed to produce a total of 160000 shp at a working pressure of 200 psi (1,378,951 Pa) and temperature of 200 °F (93.3 °C). Maximum speed would have been 32 knots (17.4 m/s)
The ships had a maximum capacity of 5000 long tons (5,080.3 t) of fuel oil
Fuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
. Using the 22000 shp cruising turbines, they had an estimated maximum range of 7000 nautical miles (12,964 km) at 16 knots (8.7 m/s). They had six turbo-driven 250 kW dynamo
Dynamo
- Engineering :* Dynamo, a magnetic device originally used as an electric generator* Dynamo theory, a theory relating to magnetic fields of celestial bodies* Solar dynamo, the physical process that generates the Sun's magnetic field- Software :...
s and two 300 kW Diesel generator
Diesel generator
A diesel generator is the combination of a diesel engine with an electrical generator to generate electrical energy....
s.
Armament
Housing the main armament in triple turrets was new to the Royal Navy though British companies had been involved in the production of triple gun turret designs for other navies. The choice of a high muzzle velocity with a relatively lighter shell was taken from the German practice; it ran counter to previous British guns such as the BL 15-inch Mark I gun of 42-calibreCaliber (artillery)
In artillery, caliber or calibredifference in British English and American English spelling is the internal diameter of a gun barrel, or by extension a relative measure of the length....
length which were lower-muzzle-velocity weapons firing heavy shells.
The G3 design mounted nine BL 16-inch Mark I 45-calibre guns in three triple hydraulically powered Mark I gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...
s, designated 'A', 'B', and 'X' from front to rear. The guns could be depressed to −3° and elevated to 40°. The ships' maximum stowage was 116 shells per gun. They fired 2048 pounds (929 kg) projectiles at a muzzle velocity
Muzzle velocity
Muzzle velocity is the speed a projectile has at the moment it leaves the muzzle of the gun. Muzzle velocities range from approximately to in black powder muskets , to more than in modern rifles with high-performance cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns...
of 2670 ft/s (813.8 m/s). Their maximum range was about 38000 yards (34,747.2 m) at maximum elevation. The G3s carried a secondary armament of sixteen BL 6-inch Mark XXII guns
BL 6 inch Mk XXII naval gun
The BL 6-inch Mk XXII gun was a British high-velocity 6-inch 50-calibre wire-wound naval gun used as secondary armament on the two Nelson class battleships, serving throughout World War II.-Ammunition:...
in superfiring
Superfire
The idea of superfire is to locate two turrets in a row, one behind the other, but with the second turret located above the one in front so that the second turret could fire over the first...
twin turrets instead of casemates—the first time in a British capital ship since the of 1904. Four turrets were sited around the forward superstructure and four at the stern. The forward turrets were provided with 150 rounds per gun and the rear turrets with 110 rounds per gun. The guns could elevate between –5° and +60°. They fired 100 pounds (45.4 kg) projectiles at a muzzle velocity of 2945 ft/s (897.6 m/s). Their maximum range was 25800 yd (23,591.5 m) at 45° elevation. Their rate of fire was five rounds per minute.
An anti-aircraft
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...
battery of six QF 4.7-inch Mark VIII guns
QF 4.7 inch Mk VIII naval gun
The QF 4.7 inch Gun Mark VIII was a British naval anti-aircraft gun designed in the 1920s for the Royal Navy. It was mounted on the two , two of the three s and the Australian submarine tender HMAS Albatross .-External links:...
was included. They had a maximum depression of -5° and a maximum elevation of 90°. They fired a 50 pounds (22.7 kg) high explosive shell at a muzzle velocity of 2457 ft/s (748.9 m/s) at a rate of eight to twelve rounds per minute. The guns had a maximum ceiling of 32000 ft (9,753.6 m), but an effective range of much less. A maximum of 256 rounds per could be carried. The ships were intended to carry four 8-barreled mountings for the 40 millimetres (1.6 in) QF 2-pounder Mark VIII gun
QF 2 pounder naval gun
The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 1.575 inch British autocannon, used famously as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing...
(commonly known as a pom-pom), two abaft the funnels and two at the stern. Each barrel was provided with 1300 rounds of ammunition. The gun fired a 40 millimetres (1.6 in) 2 pound (0.90718474 kg) shell at a muzzle velocity of 1920 ft/s (585.2 m/s) to a distance of 3800 yards (3,474.7 m). The gun's rate of fire was approximately 96–98 rounds per minute.
Like previous classes of British battlecruisers, a pair of submerged, broadside-firing torpedo tube
Torpedo tube
A torpedo tube is a device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units installed aboard surface vessels...
s were planned for these ships. Their compartment was located just forward of the 'A' shell room on the platform deck. Six 24.5 inches (62.2 cm) torpedoes per tube were to be carried in peace-time, but this would increase to eight in wartime. These Mark I torpedoes had a warhead of 743 pounds (337 kg) of TNT and were powered by oxygen-enriched air. They had two speed settings which governed their range: either 15000 yards (13,716 m) at 35 knots (19.1 m/s), or 20000 yards (18,288 m) at 30 knots (16.3 m/s).
Fire-control
The main guns of the G3 battlecruisers could be controlled from any of the three director-control towers (DCT). The primary DCT was mounted at the top of the forward superstructure. Another was mounted on the roof of the conning towerConning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....
in an armoured hood and the third was aft. Each main gun turret was provided with a 41 feet (12.5 m) coincidence rangefinder
Coincidence rangefinder
A coincidence rangefinder is a type of rangefinder that uses mechanical and optical principles to allow an operator to determine the distance to a visible object....
in an armoured housing on the turret roof. The secondary armament was primarily controlled by three DCTs. Two mounted on each side of the bridge and the third was aft. The anti-aircraft guns were controlled by a high-angle control system mounted on the very top of the forward superstructure. Each pom-pom mount had its own director and there was also a height-finder aft. Two 15 feet (4.6 m) torpedo rangefinders were located on the sides of the funnels.
Armour
A first for any British dreadnoughtDreadnought
The dreadnought was the predominant type of 20th-century battleship. The first of the kind, the Royal Navy's had such an impact when launched in 1906 that similar battleships built after her were referred to as "dreadnoughts", and earlier battleships became known as pre-dreadnoughts...
was the use of the all or nothing protection scheme in the G3s. Medium-thickness armour had proven to be useless in stopping heavy-calibre shells during World War I so the vital areas of the ship were protected by the thickest possible armour and the rest of the ship was left unarmoured. Use of this system was pioneered by contemporary U.S. Navy battleship designs starting with the . However, this system of protection required that the armoured citadel should have enough reserve buoyancy to keep the ship stable even if the rest of the hull was riddled by gunfire.
The waterline belt
Belt armor
Belt armor is a layer of heavy metal armor plated on to or within outer hulls of warships, typically on battleships, battlecruisers and cruisers, and on aircraft carriers converted from those types of ships....
of the G3 had a maximum thickness of 14 inches (36 cm) with the top of the armour angled 18° outwards. This angle increased the armor's relative thickness to horizontal, close-range fire, albeit at the cost of reducing its relative height which increased the chance of plunging shellfire going over or under it. It ran some 522 feet (159.1 m), from the forward edge of 'A' barbette to the rear of the after 6-inch magazine. The belt had a height of 14 in 3 in (4.34 m), which 4 in 6 in (1.37 m) was below the designed waterline. Only the forward 259 feet (78.9 m) of the belt had the maximum thickness, it thinned to 12 inches (30 cm) for the rest of its length. The lower edge of the belt abreast the magazines was continued down another 3 foot (0.9144 m) by a 4 inches (10.2 cm) thickness of high-tensile steel inclined at 36° to prevent a shell from reaching the magazines via a wave trough at high speed. The forward and rear ends of the belt terminated in 12-inch and 10 inches (25 cm) tranverse bulkhead
Bulkhead (partition)
A bulkhead is an upright wall within the hull of a ship or within the fuselage of an airplane. Other kinds of partition elements within a ship are decks and deckheads.-Etymology:...
s respectively. The waterline belt extended forward 46 feet (14 m) at a thickness of 6 inches that reduced to 2.25 inches (5.7 cm) in two steps.
The funnel and boiler room ventilation shafts were surrounded by an armoured box 116 feet (35.4 m) long intended to prevent shells fired from behind the ship reaching 'X' magazine. The box narrowed at an angle of 21° as it rose and had a maximum thickness of 12 inches nearest to the magazine. Aft it reduced in a series of steps to 9 inches (23 cm), 6 inches, 5 inches (13 cm) and 4 inches (10 cm). The armoured deck matched the length of the waterline belt and sloped down 2.5° to meet the upper edge of the belt. It had a maximum thickness of 8 inches (20 cm) from the 'A' barbette to partway over the mid-boiler rooms and thinned to a minimum of 4 inches over the rear engine and boiler rooms. The deck's thickness increased to 7 inches (17.8 cm) partway over the rear engine room and covered the aft 6-inch magazines. The armoured deck extended forward 46 feet over the torpedo compartment with a maximum thickness of 8 inches, thinning to 6 inches. The armoured deck's rear extension was 106 inch long and was 5 inches thick until the last 27 inch when it thinned to 3 inches (8 cm).
The turret faces were 17.5 inches (44 cm) thick while their sides ranged from 9 to 13 in (22.9 to 33 ) in thickness, and the roof was 8 inches thick. The armour of the barbettes ranged from 11 to 14 in (27.9 to 35.6 ) in thickness and it was carefully arranged to minimize the likely risk. The conning tower
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....
armour was 9 to 12 inches thick and its communications tube to the upper deck was 8 inches thick. The fire-control director atop the conning tower was protected by an armoured hood 3 to 5 inches thick.
The anti-torpedo bulge
Anti-torpedo bulge
The anti-torpedo bulge is a form of passive defence against naval torpedoes that featured in warship construction in the period between the First and Second World Wars.-Theory and form:...
s of the G3 battlecruisers were intended to withstand the explosion of a 750 pounds (340.2 kg) torpedo warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...
. They consisted of an outer air space, an inner buoyancy space and the torpedo bulkhead
Torpedo bulkhead
A torpedo bulkhead is a type of 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 was struck underneath the belt armor by a shell or by a torpedo...
that consisted of two layers of 0.875 inches (2 cm) high-tensile steel. The bulkhead was situated some 13.5 feet (4.1 m) inboard from the side of the ship. Postwar tests done on a replica of this system showed that filling the buoyancy space with water rather than the sealed steel crushing tubes as used in was just as effective and weighed less. A compressed air system was fitted to blow the water out of the buoyancy spaces and bring the ship upright in 15 minutes after two torpedo hits. The ship's double bottom
Double bottom
A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a...
ranged from 5–7 ft (1.5–2.1 ) in depth.
Cancellation
The four G3 battlecruisers were ordered in October–November 1921, without names, but the Washington Naval TreatyWashington Naval Treaty
The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...
, an arms limitation
Arms control
Arms control is an umbrella term for restrictions upon the development, production, stockpiling, proliferation, and usage of weapons, especially weapons of mass destruction...
treaty under negotiation at the time, led to the suspension of building on 18 November 1921 and outright cancellation in February 1922 because the treaty forbade construction of any ship larger than 35000 long tons (35,561.8 t). Although the ships were ordered, none were actually laid down.
Many of the aspects of their design ultimately were incorporated into the two s, and they are often described as being a cut-down G3. Indeed, the Nelsons received the design designation 'O3', marking them as next in the design sequence from the 'N3' battleship design although they used the guns intended for the G3 class for cost reasons and to comply with the Treaty's 16-inch limitation on main armament.
See also
- Lexington class battlecruiserLexington class battlecruiserThe Lexington-class battlecruisers were the only class of battlecruiser to ever be ordered by the United States Navy.The Lexington class were the only class of U.S. Navy ships to be officially referred to as battlecruisers. The World War II-era , officially classified as "large cruisers", but some...
- a contemporary, but less technically-advanced U.S. design also cancelled as a result of the Washington Treaty - a series of four battlecruisers planned for the Imperial Japanese Navy as part of the so-called Eight-eight fleet, cancelled as a result of the Washington Treaty
External links
- Teesside's battlecruiser...the ship with no name April Fool's Day hoax involving the G3 class