3-cylinder triple-expansion engines that drove two screws, with steam provided by twenty Belleville boilers. The boilers were trunked into two funnels located amidships. The Formidable-class ships had a top speed of from . Implacable had a main battery of four 40-calibre guns mounted in twin-gun turrets fore and aft; these guns were mounted in circular barbettes that allowed all-around loading or elevation. The ships also mounted a secondary battery of twelve 45-calibre guns mounted in casemates, in addition to ten 12-pounder guns and six 3-pounder guns for defence against torpedo boats. As was customary for battleships of the period, she was also equipped with four torpedo tubes submerged in the hull. Implacable had an armoured belt that was thick; the transverse bulkheads on either end of the belt were thick. Her main battery turrets sides were thick, atop barbettes, and the casemate battery was protected with 6 in of Krupp steel. Her conning tower had thick sides as well. She was fitted with two armoured decks, thick, respectively. Service history Pre-World War I HMS Implacable was laid down at Devonport Dockyard on 13 July 1898 and launched on 11 March 1899 in a very incomplete state to clear the building way for construction of battleship . She was completed in July 1901. Implacable was commissioned at Devonport Dockyard by Captain Prince Louis of Battenberg on 10 September 1901 for service on the Mediterranean Station, and left Plymouth for the Mediterranean 29 September, arriving at Malta on 8 October 1901. The gun shields for her 3-pounder guns were removed the following year. In June 1902 she was in Alexandria for the scheduled coronation festivities for King Edward VII, and in September that year she visited Nauplia in the Aegean Sea for combined manoeuvres with the Mediterranean and Channel squadrons. Captain Reginald Charles Prothero was appointed in command on 27 October 1902, serving as such until May 1904. In November 1902 she was Genoa to land Prince Louis on his departure home, and the officers of the ship attended the deferred coronation ball organized by the British colony in the city. During her Mediterranean service, she underwent refits at Malta in 1902, 1903–1904, and 1904–1905. During these refits, she had her masts revised several times as rangefinders and fire control equipment were added. She suffered a fatal accident on 12 July 1905 when a boiler explosion killed two men, and suffered another