French ironclad Océan Océan was a wooden - hulled , armored frigate built for the French Navy in the mid to late 1860s and the lead ship of her class . She was commissioned in 1870 to participate in the Franco - Prussian War and was assigned to the Baltic Squadron that unsuccessfully attempted to blockade Prussia n ports in the Baltic Sea . The ship later served in both the Northern and Mediterranean Squadron s before being discarded in 1894 . Design and description . The " Océan " - class ironclad s were designed by Henri Dupuy de Lôme as an improved version of the s . The ships were central battery ironclads with the armament concentrated amidships . For the first time in a French ironclad three watertight iron bulkheads were fitted in the hull . Like most ironclads of their era they were equipped with a metal - reinforced ram . The ship measured overall , with a beam of . " Océan " had a maximum draft of and displaced . Her crew numbered between 750 and 778 officers and men . The metacentric height of the ship was very low , between . Propulsion . The " Océan " - class ships had one horizontal return connecting rod compound steam engine driving a single propeller . Their engines were powered by eight oval boilers . On sea trials the engine produced and " Océan " reached . She carried of coal which allowed her to steam for approximately at a speed of . The " Océan " - class ships were barque or barquentine - rigged with three masts and had a sail area around . Armament . These ships had their main armament mounted in four barbette s on the upper deck , one gun at each corner of the battery , with the remaining guns on the battery deck below the barbettes . " Océan " s original armament consisted of four guns in the barbettes , and on the battery deck , four and four guns . This was to upgraded four guns in the barbettes and eight guns on the battery deck before she was commissioned . The 18 - caliber 274 - millimeter Modèle 1870 gun fired an armor - piercing , shell while the gun itself weighed . The gun fired its shell at a muzzle velocity of and was credited with the ability to penetrate a nominal of wrought iron armour at the muzzle . The armor - piercing shell of the 19 - caliber 240 - millmeter Modèle 1870 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 . At some point the ship received a dozen Hotchkiss 5 - barrel revolving guns . They fired a shell weighing about at a muzzle velocity of about to a range of about . They had a rate of fire of about 30 rounds per minute . The hull was not recessed to enable any of the guns on the battery deck to fire forward or aft . However , the guns mounted in the barbettes sponsoned out over the sides of the hull did have some ability to fire fore and aft . Late in the ship ' s career four above - water torpedo tube s were added . Armor . The " Ocean " - class ships had a complete wrought iron waterline belt . The sides of the battery itself were armored with of wrought iron . The barbette armor was thick . The unarmored portions of their sides were protected by iron plates . Gardiner says that the barbette armor was later removed to improve their stability , but this is not confirmed by any other source . Service . " Océan " was laid down at Brest in July 1865 and launched on 15 October 1868 . The ship began her sea trials on 3 December 1869 , but was not commissioned until 21 July 1870 for service during the Franco - Prussian War of 1870 – 71 . " Océan " was assigned to the Northern Squadron that attempted to blockade Prussian ports on the Baltic until the squadron was ordered to return to Cherbourg on 16 September 1870 . Afterward she was assigned to the Evolutionary Squadron until 1875 when she was placed in reserve . " Océan " was recommissioned in 1879 for service with the Mediterranean Squadron . She had a lengthy refit in 1884 – 85 and was assigned to the Northern Squadron after it was completed . Around 1888 the ship was transferred back to the Mediterranean Squadron until she was reduced to reserve around 1891 . " Océan " was assigned to the Gunnery School that same year and later became a training ship for naval apprentices before being condemned in 1894 .