General characteristics Agincourt had an
overall length of , a
beam of , and a
draught of at
deep load. She displaced at load and at deep load. The ship had a
metacentric height of at deep load. She had a large turning circle, but manoeuvred well despite her great length. She was considered to be a good gun platform. When she came to serve in the Royal Navy,
Agincourt was considered a particularly comfortable ship and very well-appointed internally. A knowledge of
Portuguese was necessary to work many of the fittings—including those in the
heads—as the original instruction plates had not all been replaced when she was taken over by the British. The steam plant consisted of twenty-two
Babcock & Wilcox water-tube boilers with an operating pressure of .
Agincourt normally carried of coal, but could carry a maximum of , as well as of
fuel oil to be sprayed on the coal to increase its burn rate. At full capacity, she could steam for at a speed of . Electrical power was provided by four steam-driven reciprocating
electrical generators.
Armament stage of her construction
Agincourt mounted fourteen
BL 12-inch Mk XIII 45-
calibre guns in seven twin hydraulically powered turrets, unofficially named after the days of the week, starting from Sunday, forward to aft. This was the largest number of turrets and heavy guns ever mounted on a dreadnought battleship. The guns could be depressed to −3° and elevated to 13.5°. They fired projectiles at a
muzzle velocity of ; at 13.5°, this provided a maximum range of just over with
armour-piercing (AP) shells. During the war the turrets were modified to increase their maximum elevation to 16°, but this only extended the range to . The rate of fire of these guns was 1.5 rounds per minute. When a full
broadside was fired, "the resulting sheet of flame was big enough to create the impression that a battle cruiser had blown up; it was awe inspiring." No damage was done to the ship when firing full broadsides, despite the common idea that doing so would break the ship in half, but much of the ship's
tableware and glassware did shatter when
Agincourt fired her first broadside. As built,
Agincourt mounted eighteen
BL 6-inch Mk XIII 50-calibre guns. Fourteen were placed in armoured
casemates on the upper deck and two each in the fore and aft superstructures, protected by
gun shields. After the ship was seized by the British, two more were added abreast
the bridge in pivot mounts, protected by gun shields. The guns could be depressed to −7° and elevated to 13°, later increased to 15°. They had a range of at 15° when firing a shell with a muzzle velocity of . Their rate of fire was about five to seven rounds per minute, but this dropped to about three rounds per minute after the ready ammunition was used up because the ammunition hoists were too slow or few to keep the guns fully supplied. About 150 rounds were carried per gun. Close-range defence against
torpedo boats was provided by ten 45-calibre
quick-firing guns. These were mounted in the superstructure in pivot mounts and protected by gun shields.
Agincourt also carried three British 21 inch torpedo| submerged
torpedo tubes; one was on each beam and the last was in the stern. The water that entered the torpedo tubes when they were fired was discharged into the torpedo flat to facilitate reloading the tube and then pumped overboard. This meant that the torpedo crewmen would be operating in of water if rapid fire was required. Ten torpedoes were carried for them.
Fire control Each turret was fitted with an armoured
rangefinder in the turret roof. In addition, another one was mounted on top of the foretop. By the time of the
Battle of Jutland in 1916,
Agincourt was possibly the only dreadnought of the
Grand Fleet not fitted with a
Dreyer fire-control table. A
fire-control director was later fitted below the foretop and one turret was modified to control the entire main armament later in the war. The armour of the barbettes constituted a major weakness in
Agincourts protection. They were 9 inches thick above the upper deck level, but decreased to 3 inches between the upper and main decks and had no armour at all below the main deck except for "Sunday" barbette (which had 3 inches), and "Thursday" and "Saturday" barbettes (which had 2 inches). The turret armour was 12 inches thick on the face, on the side and in the rear. The turret roofs were 3 inches thick at the front and 2 inches at the rear. The casemates for the secondary armament were protected by 6 inches of armour and were defended from
raking fire by 6-inch-thick bulkheads.
Wartime modifications Approximately of high-tensile steel was added to the main deck after the Battle of Jutland to protect the
magazines. Two
anti-aircraft guns were added to the quarterdeck in 1917–18. A rangefinder was added to the former
searchlight platform on the
foremast at the same time. A high-angle rangefinder was added to the
spotting top in 1918. ==Construction and seizure==