The Orinoco was built at Northfleet on the River Thames in 1851, by Pitcher. One of five similar ships owned by the Royal Mail Steam Packet Company and named after South American rivers. The company had to comply with directions from the Admiralty as to how the ships were to be built and which materials were to be used. The results were anything but successful. The Orinoco's completion date was delayed while her bulkheads were lined with zinc, after one of the sister-ships, the Amazon, caught fire, and was lost on her maiden voyage. The Orinoco was barque-rigged and paddle-driven. She was launched on May 17, 1851, making her maiden voyage in September the following year from Southampton to the West Indies, with passengers, mail and some cargo. All of the five ships were built for both mercantile and naval purposes and were fitted to carry heavy guns. The need for such drastic armament never arose although the Orinoco did carry troops to the Crimean War. These Royal Mail ships were the first vessels to be fitted with telegraphs linking the bridge with the engine room, a great step forward. Taking them all round, the sisters were not exactly lucky ships, for the Orinoco was only in service seven years. In 1858 she was discovered to have dry rot in her timbers and she was sent to Vauxhall to be broken up, an unusual event for a ship of her size for the deck fittings had to be removed to allow her to travel under the bridges of the Thames. Her engines came in useful however for they were put into the Paramatta.
Of the three remaining sisters, the Demerara ran aground while on her way to be fitted with engines and the Parana and the Magdalena both suffered mishaps during their short careers on the sea.
Cuba SG1848, Turks and Caicos SG457, Antigua SG387, Dominica SG441, Grenada SG1086, Gren of St Vincent SG215, Sea Breezes 11/71