designs. Coles enlisted the support of Prince Albert, who wrote to the First Lord of the Admiralty, the Duke of Somerset, supporting the construction of a turret ship. In January 1862, the Admiralty agreed to construct a ship, , which had four turrets and a low freeboard, intended only for coastal defence. Coles was allowed to design the turrets, but the ship was the responsibility of the chief Constructor Isaac Watts. Another of Coles's designs, , was completed in August 1864. Its existing broadside guns were replaced with four turrets on a flat deck and the ship was fitted with of armour in a belt around the waterline. Early ships like and Royal Sovereign had little sea-keeping qualities being limited to coastal waters. Coles, in collaboration with Sir Edward James Reed, went on to design and build , the first seagoing warship to carry her guns in turrets. Laid down in 1866 and completed in June 1869, it carried two turrets, although the inclusion of a forecastle and poop deck prevented the guns firing fore and aft. American developments The gun turret was independently invented by the Swedish inventor John Ericsson in America. Ericsson designed USS Monitor in 1861. Erickson's most prominent design feature was a large cylindrical gun turret mounted amidships above the low-freeboard upper hull, also called the "raft". The raft extended well past the sides of the lower, more traditionally shaped lower hull. A small armoured pilot house was fitted on the upper deck towards the bow, however, its position prevented Monitor from firing her guns straight forward. One of Ericsson's prime goals in designing the ship was to present the smallest possible target to enemy gunfire. The turret's rounded shape helped to deflect cannon shot. A pair of donkey engines rotated the turret through a set of gears; a full rotation was made in 22.5 seconds during testing on 9 February 1862. This design was technologically inferior to Coles', and made fine control of the turret difficult. If turret rotation overshot its mark it was difficult to make a correction. Either the engine would have to be placed in reverse or another full rotation was necessary. Including the guns, the turret weighed approximately ; the entire weight rested on an iron spindle that had to be jacked up using a wedge before the turret could rotate. The spindle was in diameter, which gave it ten times