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USS ''Roanoke'' was a wooden-hulled screw frigate built for the United States Navy in the mid-1850s. She served as flagship of the Home Squadron in the late 1850s and captured several Confederate ships after the start of the American Civil War in 1861. The ship was converted into an ironclad monitor during 1862–63; the first ship with more than two gun turrets in history. Her conversion was not very successful as she rolled excessively and the weight of her armor and turrets strained her hull. Her deep draft meant that she could not operate off shallow Confederate ports and she was relegated to harbor defense at Hampton Roads, Virginia for the duration of the war. ''Roanoke'' was placed reserve after the war and sold for scrap in 1883. ==Description== ''Roanoke'' was long between perpendiculars and had a beam of .〔Canney 1990, p. 174〕 The ship had a draft of 〔Silverstone, p. 17〕 and a depth of hold of . She displaced 〔 and had a burthen of 3,400 tons. ''Roanoke''s hull was strongly reinforced by wrought iron straps. Her crew numbered 674 officers and enlisted men.〔 The ship had one horizontal two-cylinder trunk steam engine driving a single propeller using steam provided by four Martin boilers. The engine produced a total of and the ship had a maximum speed of under steam alone. The propeller could be hoisted and the single funnel lowered to increase speed under sail alone. ''Roanoke'' was ship rigged and had a sail area of .〔Canney 1990, pp. 48, 51〕 In 1861, the ship's armament consisted of one smoothbore Dahlgren pivot gun, twenty-eight Dahlgren guns and fourteen Dahlgren guns.〔 The 10-inch Dahlgren weighed and could fire a shell up to a range of at +19° elevation. The nine-inch gun weighed and could fire a shell to a range of at an elevation of +15°. The eight-inch Dahlgren had a range of at an elevation of +10° with a shell. It weighed .〔Olmstead, et al, pp. 87–88〕 ===Steam frigate service=== ''Roanoke'', named after the Roanoke River,〔''Roanoke''〕 was laid down at the Norfolk Navy Yard in May 1854 and launched on 13 December 1855. The ship sank when launched and had to be refloated before she could be completed.〔 She was commissioned on 4 May 1857 with Captain John B. Montgomery in command.〔 Assigned to the Home Squadron as flagship, ''Roanoke'' transported the American filibuster and former President of Nicaragua, William Walker, and his men back to the United States from Aspinwall, Colombia, (now called Colón, Panamá). ''Roanoke'' arrived on 4 August and the ship was decommissioned at the Boston Navy Yard on 24 September 1857. Recommissioned on almost a year later on 18 August 1858, ''Roanoke'' resumed her duties as flagship of the Home Squadron. For over a year, she was stationed at Aspinwall awaiting the arrival of the first Japanese embassy to the United States to ratify the 1858 Treaty of Amity and Commerce. They reached Aspinwall on 25 April 1860 and ''Roanoke'' reached Hampton Roads on 12 May 1860 with the delegation and was again decommissioned.〔 After the start of the Civil War, ''Roanoke'' recommissioned on 20 June 1861 and was assigned to the North Atlantic Blockading Squadron. She destroyed the schooner ''Mary'' off Lockwood Folly Inlet, North Carolina, on 13 July 1861. The ship subsequently helped to capture the schooners ''Albion'' and ''Alert'' and the ship ''Thomas Watson'' off Charleston, South Carolina, on 15 October 1861.〔 ''Roanoke''s deep draft prevented her from engaging the Confederate casemate ironclad CSS ''Virginia'' (her former sister ) during the Battle of Hampton Roads on 8–9 March 1862. The ship ferried north survivors from the sailing frigates and which ''Virginia'' had sunk. She arrived at New York City on 25 March, and decommissioned the same day to begin reconstruction as a monitor.〔 ===Ironclad reconstruction=== On 19 March 1862, 10 days after the Battle of Hampton Roads where the fought the Confederate ironclad to a standstill, John Lenthall, Chief of the Bureau of Construction and Repair, and the Chief of Steam Engineering, Benjamin F. Isherwood, wrote a letter to Gideon Welles, the Secretary of the Navy recommending that ''Roanoke'' be converted into a seagoing ironclad as that would be cheaper and faster than new construction. They suggested that the ship be cut down to the top of her gun deck, armoring her sides and deck and mounting four revolving Ericsson gun turrets, each mounting two or guns. This scheme would give her an ample of freeboard. Aside from reinforcing her hull to carry the weight of the turrets, the only other changes that they recommended were the elimination of the hoisting screw, replacement by a propeller smaller in diameter, and the addition of a ram. The wrought iron side armor would be a maximum of in thickness with a taper down to at its bottom edge, about below the waterline. The deck armor was to be thick and an additional steam engine would be necessary to rotate the turrets and run the ventilation fans. They estimated that this conversion would take three and a half months and cost $495,000.〔Canney 1993, pp. 59–60〕 Welles accepted their recommendation and ''Roanoke'' began her reconstruction at the Brooklyn Navy Yard when she arrived in New York City on 25 March.〔 The navy yard removed her masts, rigging and everything above the upper deck except her funnel while the Novelty Iron Works received a contract in early April to shape and mount all of her metal work. To save weight the number of turrets was reduced to three and her deck armor to . Each turret was virtually identical to those of the s and consisted of eleven layers of plates.〔Canney 1993, pp. 60–61〕 The forward two turrets were surmounted by a stationary pilothouse with armor nine inches thick.〔 Novelty was given a choice in protecting ''Roanoke''s sides, it could either with six layers of plates or a single plate thick that reduced to inches below the waterline. It chose the latter and delays in their delivery were largely responsible for drawing out the reconstruction time to around a year.〔 The plates were manufactured by the "Franklin Forge" of Tugnot, Dally & Co. An auxiliary boiler was added to provide steam for the engines that powered the turrets, fans and steering and little to nothing was done to reinforce the hull to withstand the weight of her armor and turrets. The deck beneath each turret was reinforced by a series of stanchions that transferred their weight to the ship's bottom, which was not reinforced to handle their weight. The stress caused ''Roanoke'' to leak around per day by the end of the war. In her new configuration, her crew numbered 347 officers and men.〔Canney 1993, pp. 61–62〕 ''Roanoke'' was armed with two muzzle-loading smoothbore 15-inch Dahlgren guns, two Dahlgren guns and a pair of eight-inch, 150-pounder Parrott rifles. The forward turret mounted one 15-inch Dahlgren and a 150-pounder Parrot rifle, the middle turret was fitted with 15- and 11-inch Dahlgrens and the aft turret with one 11-inch Dahlgren and a 150-pounder rifle.〔Chesneau & Kolesnik, p. 120〕 Shortages of the 15-inch Dahlgren forced the substitution of two 11-inch Dahlgrens. Each of the former guns weighed approximately . They could fire a shell up to a range of at an elevation of +7°. The 11-inch Dahlgren weighed and could fire a shell up to a range of at +5° elevation.〔Olmstead, et al, pp. 90, 94〕 The 150-pounder Parrot rifle weighed and fired eight-inch shells that weighed .〔Silverstone, p. xx〕 ''Roanoke'' was also fitted with an ax-shaped ram. It was formed from two 4.5-inch plates that projected past her bow and presumably was the height of a single plate, .〔Canney 1993, p. 61〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「USS Roanoke (1855)」の詳細全文を読む スポンサード リンク
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