St. Vincent-class battleship

The St. Vincent-class battleships consisted of three ships of the Royal Navy laid down in 1908, and completed between May 1909 and April 1910. They were St. Vincent, Collingwood, and Vanguard. Vanguard was destroyed in an ammunition explosion, probably due to bagged cordite.

Visually, they were very difficult to distinguish from the Bellerophons. The major innovation in this class was the adoption of longer 50 calibre main armament, increased from the 45 calibre fitted to previous classes.

Design
The selection of a gun five feet longer than before necessitated a hull ten feet longer between "X" and "Y" turrets to maintain clearance between the guns and the superstructure. The longer hull required an extra beam of 18 inches to maintain the correct hull form ratios. This produced a general scaling-up of 650 tons over the preceding class.

Armor distribution was slightly changed. The inadequate 10 inch thickness for the main belt was retained, but lengthened slightly. Maximum main deck armour thickness was slightly increased, but in compensation middle deck thickness had to be reduced.

The power plant was also increased over the previous class, resulting in a design speed ¼ knot faster than before. But in practice, the difference was marginal.

In service, the 50 calibre Mark XI was not considered a success. In exchange for a very slightly superior penetrating performance, it suffered from excessive barrel droop and bore erosion. Secondary armament was also increased from 16 to 20 four-inch (102 mm) guns.

These ships were the last British ships with symmetrically placed wing turrets. The following Neptune class had a staggered wing turret arrangement in an attempt to get a 10-gun broadside.