RMS Mooltan was an ocean liner and Royal Mail Ship of the Peninsular and Oriental Steam Navigation Company (P&O). She was ordered in 1918 and completed in 1923. She served in the Second World War first as the armed merchant cruiser HMS Mooltan (F75) and then as a troop ship. She was retired from P&O service in 1953 and scrapped in 1954.
Mooltan was unusual in combining both quadruple-expansion steam engines and turbo-electric transmission. When completed in 1923 she had only her quadruple-expansion engines, but in 1929 turbo generators and electric propulsion motors were added alongside them to increase her speed.
Building
P&O ordered Mooltan and her sister from Harland and Wolff Ltd on 29 November 1918. Mooltan was given yard number 587. She was launched on 15 January 1923, completed on 22 September 1923, undertook sea trials and was handed over to her owners on 21 September 1923.
She was named Mooltan after the city of Multan in the Punjab, and an earlier "RMS Mooltan (1905–1917)", that was lost to enemy action in 1917, which was in turn named after a still earlier "SS Mooltan (1861–1884)", a Peninsular and Oriental Company's screw steamer whose maiden voyage was from Southampton in 1861. This ship was withdrawn from service in 1874 and laid up in London. In 1880, she was sold to Messrs Elles & Co of Liverpool, and again to J. J. Wallace of London. In 1884 she was sold again, this time to J. Pedley of London, and renamed the "Eleanor Margaret" and underwent conversion to a four masted barque. In 1888 sold yet again to J. D. Bischoff of Bremen. In 1891, she sailed from Newcastle upon Tyne for Valparaiso, and was reported missing in the North Atlantic. Last known position being 45°N, 25°W.
The new Mooltan was the first P&O ship to exceed 20,000 tons. She had 56 corrugated furnaces heating six double-ended and two single-ended boilers that had a combined heating surface of . These supplied steam at 215 lbf/in2 to her two four-cylinder inverted direct acting quadruple-expansion steam engines.
Mooltan had broad decks and gained a reputation for great steadiness, but her speed was sacrificed for reliability and comfort. She had a small rudder that impaired handling. She had two funnels, but the second was a dummy that served as an engine room ventilator rather than a smokestack.
Mooltan was finished in P&O's traditional colours: her hull black with a white band, her boot topping red, her upper works and lifeboats buff, her large vents black, her small vents buff and her two funnels black.
Pre-war service
Mooltan started her maiden voyage on 5 October 1923. She left the Port of Tilbury, sailed via Suez canal and called at Colombo, Ceylon (Sri Lanka) and Melbourne before reaching Sydney, Australia on 21 December 1923.
In 1929 Mooltans engines were supplemented with British Thomson-Houston exhaust-driven turbo generators powering electric propulsion motors. The addition of turbo-electric power alongside her original quadruple-expansion engines increased her total installed power to 2,878 NHP and raised her top speed to . Her accommodation was also revised.
In 1931 all her accommodation was again revised and improved. In 1933 Mooltan carried Douglas Jardine's MCC cricket test team home to England after the controversial "Bodyline" Test Series. In 1938 she was altered to allow her to carry chilled beef.
War service
On 6 September 1939, just after the outbreak of the Second World War, Mooltan was requisitioned to be an armed merchant cruiser. Her conversion included removing her dummy second funnel to improve the arc of her anti-aircraft guns. Later on in the war the funnel was replaced but in a shorter form. On 15 October 1939 she was commissioned into the Royal Navy as HMS Mooltan (F75).
Her naval service was divided between the South Atlantic Station (October 1939 – April 1940 and June – July 1940) and the Freetown Escort Force (May 1940 and August 1940 – January 1941). Mooltan did not lose any of the merchant vessels that she escorted. On 31 July 1940 she was in the Western Approaches en route from Plymouth to Freetown when a German reconnaissance aircraft attacked her, but she survived intact.
On 20 January 1941 Mooltan was returned for conversion to a Ministry of War Transport troop ship. The work was started by R&H Green and Silley Weir Ltd in Tilbury and completed at Newcastle upon Tyne by May 1941. In 1941 she carried troops out to the Middle East.