St Vincent-class battleship

The three St Vincent-class battleships were built for the Royal Navy in the first decade of the 20th century. They were St Vincent, Collingwood, and Vanguard. Vanguard was destroyed in an ammunition explosion, probably due to bagged cordite.

Background and description
The design was a slightly enlarged version of the previous s. The Admiralty saw a potential threat to the naval security of Great Britain in the building programme of German dreadnoughts, and decided to construct a significant modern battle fleet as fast as possible. Building to an existing concept clearly saved time. It was intended that there should be initially a core battle-fleet of eight similar battleships; HMS Dreadnought (1906), three Bellerophons, three St Vincents and one further unnamed ship, later authorised as HMS Neptune (1909).

In comparison to the Bellerophon class, the displacement of the St Vincents was increased by 650 LT; the length was increased by 10 ft and the beam by 18 in. A more powerful main armament gun was shipped; the armour protection of the hull was slightly improved; total fuel capacity was marginally increased; and the design speed was increased.

Armament
The main armament consisted of ten 12-inch (305 mm) Mark XI 50-calibre guns carried in five twin turrets. The increase in length over earlier ships, from 45-calibre to 50-calibre, produced an increase in muzzle velocity from 2,850 to 3,101 feet/second for the same weight of armour-piercing shell. This produced an increase in armour penetration of about half an inch at a range of 3,000 yards but muzzle wobble reduced accuracy, with salvoes being spread over a greater area than had been the case with previous ships.

The turret arrangement was the same as in all earlier British dreadnoughts. "A" turret was positioned on the forecastle deck, with an unobstructed arc of fire over the bow of some 270 degrees. "P" and "Q" turrets were placed, one on either beam, on the maindeck at a level between the funnels; each had a nominal arc of fire of 180 degrees, being from dead ahead to dead astern. As these two turrets were positioned symmetrically on the ship there was no possibility of firing across the deck on the opposite beam, and in practice firing too close to the long axis of the ship caused unacceptable damage to the superstructure. "X" turret was positioned between the after funnel and the after superstrucure, at maindeck level. The guns of this turret had an arc of fire of some 110 degrees on either beam, with no ability to fire either astern or ahead. "Y" turret, on the quarterdeck at main deck level, had an uninterrupted arc of fire over the stern of some 300 degrees.

The secondary, or anti-torpedo armament, comprised eighteen four-inch (102 mm) Mark III 50-calibre quick-firing (QF) guns. Pairs of these guns were installed in unshielded mounts on the roofs of "A", "P", "Q" and "X" turrets, and the other ten were positioned in single mounts at forecastle-deck level in the superstructure. The guns on "A" turret were removed in 1911. In 1917, when it became necessary to arm merchant ships as a defence against German submarines, a number of smaller guns were removed from capital ships to meet the need. All guns were removed from the turret roofs but some were replaced in new positions in the forward superstructure and at the base of the after funnel. Collingwood finished the war with a total of thirteen guns of this size, including one anti-aircraft gun placed between the funnels.

One 12 pounder (three-inch) anti-aircraft gun was fitted, and four three-pounder saluting guns were also carried.

There were three torpedo tubes of 18-inch (457 mm) calibre, one on either beam and one astern. All were designed to discharge their torpedoes underwater; a total of nine torpedoes were carried.

Armour
The main waterline belt was of armour ten inches thick and ran from a point level with the forward point of "A" barbette to a point level with the after point of "Y" barbette. The lower edge extended, at normal draught, to four feet eleven inches below the waterline. Above the main deck running for the same length, was an upper belt of eight inches thickness which reached to a height of eight feet seven inches above the normal draught waterline. Forward of "A" barbette the main belt was extended, with armour seven inches thick, approximately one third of the distance to the bow. From this point and from the after end of the belt to the stern, the waterline was protected by two-inch armour only.

A transverse bulkhead of five-inch armour ran from beam to beam across the forward part of the ship from the ends of the seven-inch part of the armour belt: it extended from the level of the lower deck to the maindeck. The after bulkhead ran straight across the ship from the after ends of the ten-inch main belt. It also extended from lower deck to maindeck level and was eight inches thick.

There were three armoured decks. The maindeck had armour varying between three-quarters of an inch and one and a half inches; the middle deck was one and three-quarters inches and the lower deck was one and a half to three inches thick. The thickness of the decks was determined by the presence or absence of nearby armoured structures and by the relative importance of structures being protected. Maximum protection was given to magazines and machinery.

The main turret faces were protected by armour eleven inches thick and their barbettes by armour of five inches to nine inches. Protection here varied according to the degree of protection afforded by surrounding structures and by the armoured decks.

The conning tower received armour of eight inches to eleven inches, the more vulnerable aspect again getting the greater protection.

Machinery
Four shafts were directly driven by four Parsons turbines, supplied with steam by eighteen Yarrow large-tube boilers with a normal working pressure of 235 pounds/square inch (PSI). The designed shaft horse-power (SHP) was 24,500 and the designed maximum speed was 21 knots. The normal load of coal was 900 tons but up to 2,700 tons could be carried, together with 850 tons of fuel oil. The radius of action at 10 knots was 4,690 nautical miles using coal only or 6,900 nautical miles when oil was sprayed onto the coal. The radius at 18.7 knots was 4,250 miles.