HMS Audacious was the lead ship of the s built for the Royal Navy in the late 1860s. They were designed as second-class ironclads suitable for use on foreign stations and the ship spent the bulk of her career on the China Station. She was decommissioned in 1894 and hulked in 1902 for use as a training ship. The ship was towed to Scapa Flow after the beginning of the First World War to be used as a receiving ship and then to Rosyth after the war ended. Audacious was sold for scrap in 1929.
Design and description
The Audacious-class ironclads were laid out as central battery ironclads with the armament concentrated amidships. They were the first British ironclads to have a two-deck battery with the upper deck guns sponsoned out over the sides of the hull. The ships were fitted with a short, plough-shaped ram and their crew numbered 450 officers and men.
HMS Audacious was long between perpendiculars. She had a beam of and a draught of . The ship was first British ironclad to be completed below her designed displacement; this meant that she was top heavy and required of cement ballast to raise her metacentric height. Audacious, and her sisters, were the steadiest gun platforms among the large British ironclads of their era. Audacious was given an experimental zinc sheath for her hull in an attempt to reduce biofouling that proved unsuccessful.
Propulsion
Audacious had two 2-cylinder horizontal return connecting rod steam engines made by Ravenhill, each driving a single propeller. The bronze four-bladed Mangin propellers were not arranged in the usual radial cross shape, but rather in two pairs, one behind the other, on an elongated boss in an attempt to reduce their drag when the ship used her sails. They were later replaced by two-bladed Griffiths propellers. Six rectangular boilers provided steam to the engine at a working pressure of . The engines produced a total of during sea trials on 21 October 1870 and Audacious reached a maximum speed of . The ship carried of coal, enough to steam at .
The Audacious-class ironclads were initially ship rigged and had a sail area of . After the loss of in a storm in 1870, the ships were modified with a barque rig which reduced their sail area to . They were slow under sail, only , partly due to the drag of the twin screws, and their shallow draft and flat bottom meant that they were leewardly when close-hauled. The three ships, Audacious, , and , with balanced rudders were described as unmanageable under sail alone.
Armament
HMS Audacious was armed with ten 9-inch and four 64-pounder rifled muzzle-loading guns. Six of the guns were mounted on the main deck, three on each side, while the other four guns were fitted above them on the upper deck. Their gun ports were in each corner of the upper battery and could be worked in all weathers, unlike like the guns on the main deck below them. The 64-pounder guns were mounted on the upper deck, outside the battery, as chase guns. The ship also had six 20-pounder Armstrong guns for use as saluting guns.
The shell of the 14-calibre 9-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 64-pounder gun weighed and fired a , shell that had a muzzle velocity of .
In 1878 Audacious received four torpedo launchers that were carried on the main deck, outside the armoured battery. When the ship was refitted in 1889–90 she received eight 4-inch breech-loading guns as well as four quick-firing 6-pounder Hotchkiss and six 3-pounder Hotchkiss guns for defence against torpedo boats.
Armour
Audacious had a complete waterline belt of wrought iron that was thick amidships and tapered to thick at the bow and stern. It only protected the main deck and reached above the waterline at full load and below. The guns were protected by a section of 8-inch armour, long, with a transverse bulkhead forward and a bulkhead to the rear. The armour was backed by of teak. The total weight of her armour was .
Service
HMS Audacious was ordered on 29 April 1867 from Robert Napier in Govan, Glasgow. She was laid down on 26 June 1867 and launched on 27 February 1869 in a gale. The winds caught the rear of the ship as she was about halfway down the slipway and twisted her enough that some plates and frames of her bottom were damaged. The ship was completed on 10 September 1870 and commissioned the following month. She cost £256,291 to build.