HMS Cyclops ( 1871 ) HMS " Cyclops " was the lead ship of the breastwork monitor s built for the Royal Navy during the 1870s . The ships were ordered to satisfy demands for local defence during the war scare of 1870 , but the pace of construction slowed down tremendously as the perceived threat of war declined . The ship spent most of her career in reserve ; her only sustained period in commission was four months in Portland Harbour , during the Russo - Turkish War in 1878 when the British were trying to force the Russians to end the war without allowing them to seize Constantinople . " Cyclops " was sold for scrap in 1903 . Design and description . The ostensible reason why these ships were ordered was for local coast defence during the war scare during the Franco - Prussian War of 1870 , but they were chosen for several other reasons . They were small and cheap , and their shallow draft was thought to limit them to defensive operations , which appealed to economy and defence - minded Members of Parliament . The Admiralty , however , envisioned them attacking shallow - water ports that larger ironclads could not enter and operating in the shallow waters of the Baltic Sea . The ships used the basic design of the " Cerberus " - class breastwork monitors to reduce design and construction time . Their hulls were completed very quickly , but the pace of building reduced as the likelihood of their immediate use diminished . They were delivered to the Royal dockyards in 1872 and commissioned for fitting out , but a number of years elapsed before that process was completed as little sense of urgency remained . The ships had a length between perpendiculars of , a beam of , and a draught of at deep load . They displaced . Their crew consisted of 156 officers and men . The " Cyclops " - class ships and other ships of her type were described by Admiral George Alexander Ballard as being like " full - armoured knights riding on donkeys , easy to avoid but bad to close with . " While not unfit to face heavy weather their decks were frequently awash in even a moderate sea . Their accommodations were rated the worst in the fleet , referred to by ordinary seamen as " ratholes with tinned air " . Propulsion . " Cyclops " had two 4 - cylinder inverted compound steam engines made by John Elder , each driving a single propeller . The ship ' s boilers had a working pressure of . The engines produced a total of on 30 December 1871 during the ship ' s sea trials which gave her a maximum speed of . " Cyclops " carried of coal , enough to steam at . Armament . The ships mounted a pair of 10 - inch rifled muzzle - loading guns in each turret . The shell of the gun weighed while the gun itself weighed . The gun had a muzzle velocity of and was credited with the ability to penetrate a nominal of wrought iron armour at . The guns could fire both solid shot and explosive shells . They were mounted on carriages that used hydraulic jacks to elevate and depress the guns . Armour . The " Cyclops " - class ships had a complete waterline belt of wrought iron that was thick amidships and thinned to at the ends . The superstructure and conning tower was fully armoured , the reason it was called a breastwork , with of wrought iron . The gun turret s had 10 inches on their faces and 9 inches on the sides and rear . All of the vertical armour was backed by of teak . The decks were thick . Construction . HMS " Cyclops " was laid down on 10 September 1870 by the Thames Ironworks in London . She was launched on 18 July 1871 and commissioned in January 1872 . The ship was towed to Devenport that same month for what proved to be a very lengthy fitting out period that was not completed until 4 May 1877 . " Cyclops " cost £156 , 782 to build . Refit . Although a recommendation had been made while the ships were still under construction to extend the superstructure out to the sides of the ship to improve their stability and habitability , this was not acted upon until they were refitted during the 1880s . This refit also strengthened the breastwork and upper decks , added another watertight bulkhead as well as a false keel . Four quick - firing 3 - pounder Hotchkiss guns were added on the breastwork for torpedo boat defence as well as five machine gun s and several searchlights . This increased their crew to approximately 191 men and added to their displacement . Service . HMS " Cyclops " was the third ship to be completed , although she was the lead ship of the class . She was placed in 1st Class Reserve after her completion . The ship , along with her sisters , was commissioned between April and August 1878 during the Russo - Turkish War for service with Admiral Sir Cooper Key ' s Particular Service Squadron in Portland Harbour . " Cyclops " was paid off at Chatham in August 1878 and refitted in 1887 – 89 . All four ships of the class participated in the annual fleet manoeuvers in 1887 , 1889 – 90 and 1892 ; in between times they were in Fleet Reserve . HMS " Cyclops " , like all of her sisters , was placed on the non - effective list in 1901 and sold on 7 July 1903 for £8 , 400 .