Overview Dreadnought was significantly larger than the two ships of the
Lord Nelson class, which were under construction at the same time. She had an
overall length of , a
beam of , and a
draught of at deep load. She displaced at normal load and at deep load, almost more than the earlier ships. She had a
metacentric height of at deep load and a complete
double bottom. Officers were customarily housed aft, but
Dreadnought reversed the old arrangement, so that the officers were closer to their action stations. This was very unpopular with the officers, not least because they were now berthed near the noisy auxiliary machinery while the turbines made the rear of the ship much quieter than they had been in earlier steamships. This arrangement lasted among the British dreadnoughts until the of 1910. She had two paired sets of
direct-drive turbines, each of which drove two diameter, three-bladed propellers using steam provided by 18
Babcock & Wilcox boilers that had a working pressure of . The turbines, rated at , were intended to give a maximum speed of 21 knots; the ship reached from during her
sea trials on 9 October 1906.
Dreadnought carried of coal, and an additional of
fuel oil that was to be sprayed on the coal to increase its burn rate. At full capacity, she could steam for at a speed of .
Armament are mounted on the roof for defence against torpedo boats.
Dreadnoughts main armament consisted of ten 45-
calibre BL 12-inch Mark X guns in five twin Mark BVIII
gun turrets. The forward turret ('A') and two aft turrets ('X' and 'Y') were located along the
centreline of the ship. Two
wing turrets ('P' and 'Q') were located
port and starboard of the forward superstructure respectively.
Dreadnought could deliver a
broadside of eight guns between 60° before the beam and 50°
abaft the beam. Beyond these limits she could fire six guns aft, and four forward. On bearings 1° ahead or astern she could fire six guns, although she would have inflicted
blast damage on the
superstructure. The guns could be depressed to −3° and
elevated to +13.5°. They fired projectiles at a
muzzle velocity of , giving a maximum range of with
armour-piercing (AP) 2
crh shells. Using the more aerodynamic, but slightly heavier, 4 crh AP shells extended the range to . The rate of fire of these guns was about two
rounds per minute. The ships carried 80 rounds per gun. The guns had an elevation range between −10° and +20°. They fired projectiles at a muzzle velocity of . The guns had a
rate of fire of 20 rounds per minute. The ship carried three hundred rounds for each gun. The original plan was to dismount the eight guns on the
forecastle and
quarterdeck and stow them on chocks on the deck during daylight to prevent them from being damaged by muzzle blast from the main guns. Gun trials in December 1906 proved that this was more difficult than expected and the two port guns from the forecastle and the outer starboard gun from the quarterdeck were transferred to turret roofs, giving each turret two guns. The remaining forecastle guns and the outer port gun from the quarterdeck were removed by the end of 1907, which reduced the total to twenty-four guns. During her April–May 1915 refit, the two guns from the roof of 'A' turret were reinstalled in the original positions on the starboard side of the quarterdeck. A year later, the two guns at the rear of the superstructure were removed, reducing the ship to twenty-two guns. Two of the quarterdeck guns were given high-angle mounts for
anti-aircraft duties and the two guns abreast the
conning tower were removed in 1917. A pair of
QF six-pounder () Hotchkiss anti-aircraft guns on high-angle mountings were mounted on the quarterdeck in 1915. They had a maximum depression of −8° and a maximum elevation of +60°. They were replaced by a pair of
QF 3-inch 20 cwt guns on high-angle Mark II mounts in 1916. These guns had a maximum depression of 10° and a maximum elevation of 90°. They fired a 12.5-pound shell at a muzzle velocity of at a rate of 29 rounds per minute. They had a maximum effective ceiling of . Firing trials against in 1907 revealed this system's vulnerability to gunfire, as its spotting top was hit twice and a large splinter severed the voice pipe and all wiring running along the mast. To guard against this possibility,
Dreadnoughts
fire-control system was comprehensively upgraded during her refits in 1912–13. The rangefinder in the foretop was given a gyro-stabilized Argo mount and 'A' and 'Y' turrets were upgraded to serve as secondary control positions for any portion or all of the main armament. An additional 9-foot rangefinder was installed on the
compass platform. In addition, 'A' turret was fitted with another 9-foot rangefinder at the rear of the turret roof and a Mark I
Dreyer Fire Control Table was installed in the main Transmitting Station. It combined the functions of the Dumaresq and the range clock. Fire-control technology advanced quickly during the years immediately preceding the First World War, and the most important development was the director firing system. This consisted of a
fire-control director mounted high in the ship which electrically provided data to the turrets via pointers, which the turret crew were to follow. The director layer fired the guns simultaneously which aided in spotting the shell splashes and minimised the effects of the roll on the dispersion of the shells. A prototype was fitted in
Dreadnought in 1909, but it was removed to avoid conflict with her duties as flagship of the Home Fleet. Preparations to install a production director were made during her May–June 1915 refit and every turret received a rangefinder at the same time. The exact date of the installation of the director is not known, other than it was not fitted before the end of 1915, and it was most likely mounted during her April–June 1916 refit. showing the armour layout The turret faces and sides were protected by 11 inches of armour, while the turret roofs used 3 inches of
Krupp non-cemented armour (KNC). The exposed faces of the barbettes were 11 inches thick, but the inner faces were 8 inches thick above the main deck. 'X' barbette's was 8 inches thick all around. Below the main deck, the barbettes' armour thinned to four inches except for 'A' barbette (eight inches) and 'Y' which remained 11 inches thick. The thickness of the main
deck ranged from . The middle deck was thick on the flat and where it sloped down to meet the bottom edge of the main belt. Over the magazine for 'A' and 'Y' turrets it was 3 inches thick, on slope and flat both. The lower deck armour was forward and 2 inches aft where it increased to 3 inches to protect the steering gear.
Electrical equipment Electrical power was provided by three 100 kW, 100 V
DC Siemens generators, powered by two Brotherhood steam and two Mirrlees diesel engines (which later changed to three steam and one diesel). Among the equipment powered by 100 volt DC and 15 volt DC electrical systems were five lifts (elevators), eight coaling winches, pumps, ventilation fans, lighting and telephone systems. ==Construction==