HMS St George was a 120-gun, three-deck, first rate, broadened built for the Royal Navy during the 1830s. Completed in 1840, the ship remained in ordinary until 1850 and served as a guard ship. St George was razeed and converted into a steam-powered, 89-gun, second rate, two decker in 1858âÂÂ1859.
The Caledonia class was an improved version of with additional freeboard to allow them to fight all their guns in heavy weather. St George measured on the gundeck and on the keel. She had a beam of , a depth of hold of , a deep draught of and had a tonnage of 2719<small></small> tons burthen. Her crew numbered 820 officers and ratings in peacetime and 900 in wartime. The ship was armed with 120 muzzle-loading, smoothbore guns that consisted of thirty 32-pounder (56 cwt) guns and two 68-pounder carronades on her lower gundeck, thirty-two 32-pounder 55 cwt guns and two 68-pounder carronades on her middle gundeck and thirty-two 32-pounders and two 68-pounder carrondaes on her upper gundeck. Her forecastle mounted a pair of 32-pounder 49 cwt guns and two 32-pounder carronades. On her quarterdeck she carried sixteen 32-pounder carronades. St Georges armament was later modified with four shell guns that replaced her 68-pounder carronades on the lower and middle gundecks. The 68-pounder carronades on the upper gundeck were replaced by a pair of 32-pounders. All of the guns on the forecastle and quarterdeck were replaced by six 32-pounders and fourteen short 32-pounder guns.
St George was ordered on 2 June 1819, laid down at Plymouth Dockyard in May 1827, launched on 27 August 1840 and completed in July 1850 as a guard ship. While in the dockyard and before being put to sea she was at risk of destruction. The dockyard suffered severe damage in a large scale fire on 25 September 1840; it started in the North Dock on and were completely gutted, threatened , and spread to nearby buildings and equipment. Estimates for the damage were put at ã150,000 in the values of the day, and would have totalled ã500,000 had the fire not been contained by demolishing several surrounding buildings. The ship's first commission was on 31 August under Captain Joseph Nias when she became the flagship of Commodore Lord John Hay, guard ship at Devonport.
She was fitted with screw propulsion in 1858âÂÂ1859, and was sold out of the service in 1883.