Brother [or possibly half-brother] of Admiral Sir Fairfax Moresby (1786–1877), and uncle to Admiral John Moresby (1830–1922), for whom Port Moresby in Papua New Guinea is named, Robert was a captain of the East India Company’s Bombay Marine — Indian Navy. Moresby is best known for his work as part of the first modern survey of the northernmost section of the Red Sea (1829–32).
His biography in the Memoirs of Hydrography (1885), reports that his earliest known survey was of the Straits of Durian in 1822, the subsequent chart being published by James Horsburgh in 1827. In command of the EIC – English East India Company — ship Thetis in 1829, Moresby escorted the first coal ship up the Red Sea. This direct charge into the steam age was achieved by leaving coal deposits at strategic places along the coast. However, the collier was shipwrecked and sank on its return journey, a fate that was put down to the lack of accurate charts. As a result, Moresby and Captain Sir Thomas Elwon were ordered to conduct a thorough survey of the region. Moresby commanded the Palinurus, and was sent to cover the region south of Suez and north of Jeddah; Elwon, in the Benares (which ran aground more than forty times during the mission), the area to the south of Jeddah to Bab-el-Maudel. Sir Clements Robert Markham wrote of the survey: “No expense was spared in fitting out the expedition, and all the surveying appliances of the day were provided, besides ample supplies of well-found boats and tenders. The latter were native craft with Arab crews. The sea was then practically unknown, and great dangers and privations were inseparable from such a service”.
The resulting two charts were first published in 1836, including Moresby’s own Chart of the Red Sea: comprising the part above Jiddah, on Mercator’s Projection, compiled from a stasimetric survey executed in the years 1830, 31, 32 and 33 in the Hon. Company’s Ship Palinurus, on two sheets; the accompanying sailing directions, Sailing Directions for the Red Sea, in 1841. Together they marked a scientific and practical turning point in the success of navigating the Red Sea by steam.
After the completion of the Red Sea Survey, and on Horsburgh’s recommendation, Moresby was sent to chart various coral island groups lying across the track of India-to-Cape trade. In 1834–36, assisted by Lieutenants Christopher and Young, they drew the first accurate maritime charts of the Maldive Islands. This was followed by the Chagos Archipelago in 1837. Both surveys were accompanied by detailed sailing directions. After returning to Bombay in 1838, Moresby was suffering such great ill-health that he was dispatched back to England.