RMS Atrato (1853)

"SS Atrato of the Royal Mail Steam Packet Company", painted by William Frederick Mitchell
History
United Kingdom
Name:	Atrato (1853–80) Rochester (1880–84)
Namesake:	Atrato River in Colombia (1853–80) Rochester, Kent (1880–84)
Owner:	RMSP Co (1853–70) John Morrison & Co (1872–79) Henry T Horn (1879–80) Adamson & Ronaldson (1880–84)
Operator:	Aberdeen Line (1872–)
Route:	Southampton – Caribbean (1853–70)
Builder:	Caird & Company, Greenock
Yard number:	26
Launched:	26 April 1853
Identification:	UK official number 13926
Fate:	sank 1884
General characteristics
Type:	iron-hulled steamship
Tonnage:	1853: 3,467 GRT, 2,260 NRT 1872: 3,184 GRT 2,051 NRT
Length:	1853: 350 feet (110 m) 1872: 335.9 feet (102.4 m)
Beam:	1853: 42 feet (13 m), 72 feet (22 m) over paddles 1872: 42.4 feet (12.9 m)
Installed power:	1853: 800 ihp 1872: 350 horsepower
Propulsion:	1853–70: 2-cylinder side-lever steam engine, side paddles 1870–84: 2-cylinder compound steam engine, single screw
Sail plan:	3-masted barquentine
Speed:	10 knots (19 km/h)

RMS Atrato was a UK iron-hulled steamship. She was built in 1853 for the Royal Mail Steam Packet Company as a side-wheel paddle steamer, and when completed was the World's largest passenger ship. She was a Royal Mail Ship until 1870.

In 1870 RMSP traded her in and in 1872 she was converted to a single screw ship with a compound steam engine. From 1872 Aberdeen Line chartered her to run to Victoria and New Zealand. In 1880 she was renamed Rochester. She sank in 1884.

Until 1850 RMSP secured its first contract to carry mail between the UK, Brazil and the River Plate. It ordered five large new wooden-hulled sister ships to take over scheduled services on its premier route between Southampton and the Caribbean, thus releasing older RMSP ships to start its new service to Rio de Janeiro, Montevideo and Buenos Aires.

One of the new ships, the 2,318 NRT Demerara, was built in Bristol by William Patterson Shipbuilders, but her engined were built by Caird & Company of Greenock. After her launch in November 1851 a steam tug started to tow from Bristol to Greenock for her engines to be installed. But the tug master lacked experience of the winding Avon and lost control of Demerara, which became wedged against both banks. When the tide went out the ship was left bridging the river, and suffered structural distortion from the 1,200 tons of ballast in her engine room.