HMS James Watt was a second-rate ship of the line of the Agamemnon class, built for the Royal Navy in the 1850s. Measuring 230 feet 3 inches (70.2 meters) on the gundeck and 194 feet 6 inches (59.3 meters) along the keel, she had a beam of 55 feet 5 inches (16.9 meters), a depth of hold of 24 feet 8 inches (7.5 meters), and a deep draught of 19 feet 8 inches (6 meters). Her tonnage was approximately 308 3/4 tons burthen. The vessel was powered by a four-cylinder single-expansion steam engine built by Boulton & Watt, rated at 600 nominal horsepower, which drove a single propeller shaft. The engine produced 1,548 indicated horsepower, enabling a maximum speed of about 9.4 knots (17.4 km/h). The ship's crew numbered around 860 officers and ratings. Her armament comprised muzzle-loading, smoothbore guns, including thirty-four 8-inch (203 mm) shell guns on the lower gundeck, thirty-four 32-pounder (56 cwt) guns on the upper gundeck, twenty-two 32-pounder (45 cwt) guns between the forecastle and quarterdeck, and a single 68-pounder gun, making her a formidable warship of her era. Originally ordered in 1847 as an 80-gun second rate to incorporate engines from the paddle frigate Vulcan, she was renamed HMS James Watt in November 1847 in honor of the famed engineer. Reclassified during construction as a 91-gun screw-propelled ship, she was laid down at Pembroke Dock in September 1850, launched on 23 April 1853, and commissioned in January 1854. Her service included participation in the Crimean War, notably in the Baltic campaigns of 1854–1855, where she was present at Kronstadt and involved in a minor engagement near the Tolbukhin lighthouse in August 1855. Despite her impressive capabilities, her machinery proved unreliable, necessitating repeated repairs. After nearly two decades of service, HMS James Watt was sold for scrap in January 1875 and broken up at Charlton. Her design and operational history reflect the transitional period from traditional sail to steam-powered warships in the Royal Navy.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.