Beacon - class gunvessel The " Beacon " - class gunvessels were a class of composite gunboat s 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 Station s . 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 . 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 . The depth of hold was and the hull was subdivided by watertight bulkheads . 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 bilge s and a flat bottom . Admiral G . A . Ballard commented that they were built " along the lines of an extremely elongated packing crate . " 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 " , while Preston claims they " sailed like tea trays " . Their funnels were hinged to lower horizontally to reduce wind resistance while under sail . " Avon " , " Dwarf " and " Elk " were re - rigged as barquentine s 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 . The ships were initially armed with a mix of 7 - inch and 64 - pounder 56 cwt 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 gun s while the two 20 - pounder guns were mounted at the bow and stern as chase gun s . The 16 - calibre 7 - inch gun weighed and fired a shell . It was credited with the nominal ability to penetrate armour . 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 " . Service . These ships were primarily designed for service in Southeast Asian waters , including the rivers , and most of the ships spent at least one commission there . " Hornet " , " Midge " , and " Gnat " spent their whole careers there . " Gnat " s service , however , was rather short as she ran aground and was wrecked on Balabac Island , south of the Philippines , less than a year after she was commissioned . Their duties included protecting British lives and property and fighting pirates . Another major deployment area was the Gulf of Guinea in West Africa where " Fly " , " Lynx " , " Flirt " , " Dwarf " , " Beacon " , " Avon " , " Pert " , " Growler " , " Rocket " , " Hart " , and " Boxer " all spent part of one or more commissions . " Beacon " supported British coastal operations during the Third Anglo - Ashanti War in 1873 while most of the others engaged river pirates at various times . " Rocket " , " Elk " , " Dwarf " , " Beacon " , and " Avon " served at least one commission off the south - east coast of South America , while " Cracker " spent her entire career there . " Dwarf " made a port visit to Asunción , on the Paraguay River , some from the ocean during one of her tours in the region . " Teazer " , " Lynx " , " Beacon " , and " Thistle " each made one deployment to the East Indies Station where they helped to suppress the slave trade between East Africa and the Persian Gulf . " Beacon " , " Hart " , and " Growler " were deployed to the Mediterranean where the former participated in the Bombardment of Alexandria in 1882 . " Fly " , " Flirt " , " Boxer " , and " Pert " each spent a commission on fishery patrol on the Grand Banks of Newfoundland . " Boxer " was also deployed to British Columbia to maintain order with the Indian tribes there . By the early 1880s , their engines were becoming worn out and most of the ships were placed into reserve for a few years before being sold for breaking up . The machinery of " Avon " , " Dwarf " and " Elk " was in good enough shape that they were assigned as tenders to the coastguard district ships at Hull , Southampton , and Liverpool for a number of years . " Midge " was also an exception and was retained in Chinese waters until 1907 when she was sold at Hong Kong . " Elk " lasted nearly as long in harbour service as she was reclassified as a tugboat in 1890 and was then sold as a dredger in 1905 .