|
The ''Beacon''-class gunvessels were a class of composite gunboats built for the Royal Navy in the late 1860s. They were the first warships of the Royal Navy expressly designed to use the engines of an older class of ships with a different hull shape.〔 They were generally deployed overseas to the China, East Indies, West Africa, Pacific, North America and West Indies Stations. In addition to showing the flag, the ships fought pirates and suppressed the slave trade in East and West Africa. As their engines wore out in the mid-1880s, they were mostly retired and scrapped by the end of the decade. A few survived into the early 1900s as they were modified for harbour service before being sold or scrapped. ==Design and description== These ships were designed by Sir Edward Reed, the Director of Naval Construction, as replacements for the various gunvessels built for the Crimean War. Being built of green timber, their hulls were starting to rot after a decade or more in service, but their engines were still generally sound. As the older ships were broken up their engines were salvaged and transferred to ''Beacon''-class ships under construction. Combat experience against Chinese fortifications had shown that the single 32-pounder smoothbore armament of the earlier ships was not powerful enough so Reed was directed to prepare a twin-screw, shallow draft design suitable for riverine operations that incorporated a pair of steam engines from the older gunboats, a heavy armament, and enough freeboard to allow for service at sea. These rather contradictory requirements forced Reed to discard traditional wooden framing for these ships and the ''Beacon'' class became the first ships of the Royal Navy to be framed in iron with wooden planking.〔Ballard, pp. 132–34〕 The ships were long between perpendiculars and had a beam of . Forward, the ships had a draught of , but aft they drew . They displaced as built and had a burthen of 464 tons.〔Winfield, p. 294〕 The depth of hold was and the hull was subdivided by watertight bulkheads.〔Ballard, pp. 135–36〕 Their crew consisted of 80 officers and enlisted men.〔 Two different types of engines were used with this class. Twelve ships received two-cylinder horizontal return connecting rod engines built by Maudslay, Sons and Field while the remaining six got two-cylinder horizontal trunk engines from John Penn and Sons. Each engine powered a single propeller. The engines produced between which gave the ships a maximum speed between . Three cylindrical boilers provided steam to the engines, although the working pressure varied; the ships with trunk engines used while the other engines used . The ships carried of coal although no range figures are available.〔 To minimise their draught the ''Beacon''s were given a very full hull shape with squared-off bilges and a flat bottom. Admiral G. A. Ballard commented that they were built "along the lines of an extremely elongated packing crate."〔Ballard, p. 135〕 This made them steady gun platforms and gave them quite a bit of buoyancy. If they ran aground, this shape allowed them to be pulled off easily and they remained upright if stranded by a receding tide. However, this hull shape made their steering erratic at low speeds or in a following sea and they made a large amount of leeway in a strong side breeze.〔 The class was barque rigged and their best speed under sail alone was over if running before the wind, despite the drag of the propellers, which could neither be hoisted out of the water, nor feathered. In a headwind, Ballard described them as "quite unmanageable under sail alone",〔Ballard, p. 140〕 while Preston claims they "sailed like tea trays".〔Preston, p.160.〕 Their funnels were hinged to lower horizontally to reduce wind resistance while under sail. ''Avon'', ''Dwarf'' and ''Elk'' were re-rigged as barquentines after 1880. A poop deck was added in between commissions to some of the ships, but this was the only major structural change made during their careers.〔Ballard, pp. 136, 138, 140–41〕 The ships were initially armed with a mix of 7-inch and 64-pounder 56 cwt〔"cwt" is the abbreviation for hundredweight, 56 cwt referring to the weight of the gun.〕 rifled muzzle-loading guns and a pair of 20-pounder rifled breechloading guns. The and 64-pounder guns were mounted on the centreline as pivot guns while the two 20-pounder guns were mounted at the bow and stern as chase guns.〔Ballard, p. 136〕 The 16-calibre 7-inch gun weighed and fired a shell. It was credited with the nominal ability to penetrate armour.〔Chesneau & Kolesnik, p. 6〕 A lighter, , 7-inch gun developed in the 1870s replaced the heavier gun in ''Avon'' and ''Elk''. It replaced both heavy guns in ''Lynx'', ''Hornet'', ''Flirt'', and ''Rocket''.〔Ballard, p. 137〕 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「Beacon-class gunvessel」の詳細全文を読む スポンサード リンク
|