HMS Defence ( 1861 ) HMS " Defence " was the lead ship of the armoured frigate s ordered by the Royal Navy in 1859 . Upon completion in 1862 she was assigned to the Channel Fleet . The ship was paid off in 1866 to refit and be re - armed and was briefly reassigned to the Channel Fleet again when she recommissioned in 1868 . " Defence " had brief tours on the North Atlantic and Mediterranean Station s , relieving other ironclads , from 1869 to 1872 before she was refitted again from 1872 to 1874 . She became guard ship on the Shannon when she recommissioned . The ship was transferred to the Channel Fleet again in 1876 and then became guard ship on the Mersey until 1885 . " Defence " was placed in reserve until 1890 when she was assigned to the mechanical training school in Devonport in 1890 . She was renamed " Indus " when the school adopted that name and served there until sold in 1935 . Design and description . The " Defence " - class ironclads were designed as smaller and cheaper versions of the armoured frigates . This meant that they could not fit the same powerful engines of the " Warrior " - class ships and were therefore slower and had far fewer guns . The naval architect Sir Nathaniel Barnaby , a future Constructor of the Navy , considered that in terms of combat a " Defence " - class ship was worth one quarter of a " Warrior " . HMS " Defence " was long between perpendiculars and long overall . She had a beam of and a draft of . The ship displaced and had a ram in the shape of a plough . The hull was subdivided by watertight transverse bulkheads into 92 compartments and had a double bottom underneath the engine and boiler rooms . " Defence " was shorter overall and displaced over less than the " Warrior " - class ironclads . Propulsion . The " Defence " - class ships had one 2 - cylinder trunk steam engine made by John Penn and Sons driving a single propeller . Four rectangular boilers provided steam to the engine . It produced a total of . During sea trials on 10 February 1868 " Defence " had a maximum speed of . The ship carried of coal , enough to steam at . The ironclads were barque - rigged and had a sail area of . The lower masts and bowsprit were made of iron to withstand the shock of ramming . " Defence " could make about under sail and the funnel was semi - retractable to reduce wind resistance while under sail alone . The ship ' s propeller could be hoisted up into the stern of the ship to reduce drag while under sail . She was re - rigged as a barque from September 1864 to April 1866 before returning to her original ship rig . Armament . The armament of the " Defence " - class ships was intended to be 18 smoothbore , muzzle - loading 68 - pounder gun s , eight on each side on the main deck and one each fore and aft as chase gun s on the upper deck , plus four rifled breech - loading 40 - pounder guns as . This was modified during construction to eight rifled 110 - pounder breech - loading guns , ten 68 - pounders and four breech - loading guns . Both breech - loading guns were new designs from Armstrong and much was hoped of them . Six of the 110 - pounder guns were installed on the main deck amidships and the other two became chase guns ; all of the 68 - pounder guns were mounted on the main deck . Firing tests carried out in September 1861 against an armoured target , however , proved that the 110 - pounder was inferior to the 68 - pounder smoothbore gun in armour penetration and repeated incidents of breech explosions during the Battles for Shimonoseki and the Bombardment of Kagoshima in 1863 – 64 caused the navy to begin to withdraw the gun from service shortly afterwards . The solid shot of the 68 - pounder gun weighed approximately while the gun itself weighed . The gun had a muzzle velocity of and had a range of at an elevation of + 12° . The shell of the 110 - pounder Armstrong breech - loader weighed . It had a muzzle velocity of and , at an elevation of + 11 . 25° , a maximum range of . The 110 - pounder gun weighed . All of the guns could fire both solid shot and explosive shells . " Defence " was rearmed during her 1867 – 68 refit with fourteen 7 - inch and two rifled muzzle - loading guns . The new guns were heavier so fewer could be carried . The shell of the 15 - calibre 8 - inch gun weighed while the gun itself weighed . It had a muzzle velocity of and was credited with the ability to penetrate a nominal of wrought iron armour at the muzzle . The 16 - calibre 7 - inch gun weighed and fired a shell . It was credited with the nominal ability to penetrate armour . Armour . The " Defence " - class ships had a wrought iron armour belt , thick , that covered amidships . The armour extended from upper deck level to below it . 4 . 5 - inch transverse bulkheads protected the guns on the main deck . The armour was backed by of teak . The ends of the ship were left entirely unprotected which meant that the steering gear was very vulnerable . They were , however , sub - divided into many watertight compartments to minimize any flooding . Service . HMS " Defence " was laid down on 14 December 1859 by the Palmers Shipbuilding and Iron Company in Jarrow . She was launched on 24 April 1861 , commissioned on 4 December 1861 and completed on 12 February 1862 . After completion she served in the Channel Fleet until 1866 , when she paid off in Plymouth for refit and re - armament . The ship returned to the Channel Fleet in 1868 , and in 1869 she was sent to the North America station to relieve . She served with the Mediterranean Fleet from 1871 to 1872 under the command of Captain Nowell Salmon , who had earned the Victoria Cross during the Indian Mutiny in 1857 . While recovering items lost when the ironclad grounded off Pantelleria , " Defence " damaged her propeller and rudder when she briefly grounded in the trough of a wave , and was nearly blown ashore herself in March 1872 . She was paid off again for a lengthy refit in Plymouth between 1872 and 1874 and became the guard ship on the Shannon until 1876 . The ship then rejoined the Channel Fleet until 1879 and was transferred with most of that fleet to the Mediterranean while the Mediterranean Fleet patrolled the Dardanelles during the Russo - Turkish War of 1878 . " Defence " replaced her sister ship as guard ship in the Mersey until 1885 , after which she saw no further sea - going service . On 20 July 1884 the ship collided with in Lough Swilly , damaging her bow and flooding some compartments . In 1890 she was converted into a floating workshop at Devonport , and was renamed " Indus " in 1898 . She was sold for scrap at Devonport in August 1935 .