The problem steam solved
Under sail, a voyage depended on wind. A ship could be becalmed for days or driven off course, and a crossing of the same ocean might take quite different times in different seasons. Steam offered something new: a ship that could keep a more regular schedule, with a speed that did not depend wholly on the weather. That change, more than raw speed, was the first great effect of the steamship era.
Early steps
Steam-driven boats appeared on rivers and coastal waters first. The Charlotte Dundas in Scotland (1802) and Robert Fulton’s North River steamboat, usually called Clermont (1807), on the Hudson, are among the best-known early examples, and the Comet of 1812 in Scotland began a commercial passenger service. These pioneers are covered in the history of steamboat pioneers; they proved that steam could work in practice, using paddle wheels.
Crossing an ocean was harder, because early engines burned large amounts of coal. The American ship Savannah crossed the Atlantic in 1819 with an auxiliary engine, but it spent most of the time under sail. In 1838 the Sirius and the Great Western both crossed the Atlantic under steam, and the following years saw the establishment of mail steamers, with the Cunard Line starting its service in 1840 under a British government mail contract. Reliability and regularity were what made these ships worth paying for.
Paddles, screws and iron
Paddle wheels worked well on rivers and in calm water but had weaknesses at sea: they were exposed to waves, vulnerable in battle, and could leave the ship’s sides in poor balance when it rolled. The screw propeller, developed in the late 1830s by inventors including Francis Pettit Smith and John Ericsson, sat below the waterline and proved better suited to ocean work. The Great Britain of 1843, with an iron hull and a screw, showed how the two innovations could combine. Iron shipbuilding made hulls larger and stronger, and later compound and triple-expansion engines used fuel more efficiently, which gradually extended range.
Sailing ships did not vanish. Through the second half of the nineteenth century, fast sailing vessels such as clippers still earned a living on long routes, particularly where coal supplies were scarce. As engines improved, steam took over more and more trades.
Schedules and the shrinking world
The steamship allowed regular timetables. Passengers, mail and perishable cargo could be planned around departure dates, and companies advertised sailings in advance. This was a major change from the ways of the earlier packet ship lines, which sailed on set days but still depended on winds. The race for speed produced the Blue Riband, an unofficial honour for the fastest Atlantic crossing, and the broader growth of the ocean liner history that followed.
Canals joined the picture. The Suez Canal, opened in 1869, was a particular boon to steamships, because the route to Asia became much shorter and steamers could use it more easily than sailing ships, which found the canal and the Red Sea’s winds difficult. The shortcut changed the economics of the Eastern trade.
Emigration and trade
Steam changed the experience of emigration. Crossing times fell, and voyages became more predictable; in the later nineteenth century millions of Europeans travelled to the Americas and Australasia on steamships, many in steerage accommodation. Conditions in emigrant steerage varied and were often crowded, but the shorter journey and better regulation generally reduced the risks seen on earlier sailing emigrant voyages.
For cargo, steam made it possible to move bulk goods, refrigerated food (later in the century) and manufactured goods on dependable schedules. Not every trade needed speed. Many ordinary cargo carriers, known as tramp steamers, went wherever freight was offered, and these working ships carried much of the world’s commerce.
Coal and the new geography
Steamships needed fuel, and coal had to be loaded along the route. A network of coaling stations grew, many of them under British control, in places such as Gibraltar, Malta, Aden and Singapore. Control of coaling points became a strategic matter, which tied the ship to the geography of empire. Dock workers who loaded coal formed a significant part of port labour. Ship design also altered: bunkers took cargo space, and engine rooms required new trades, such as engineers and stokers.
Naval power
Navies were slower than merchants to adopt steam, partly because paddle machinery was vulnerable to gunfire and partly because they wanted to keep sailing capacity for long ranges. The screw propeller changed that. In the 1840s and 1850s navies converted or built screw-driven warships, and sail was kept as an auxiliary on many ships for some decades. Steam gave warships freedom to manoeuvre independently of the wind, which altered tactics and strategy and, together with iron and then steel armour, led to the ironclad era. By the end of the century, sail was almost entirely gone from front-line warships.
A mixed legacy
The steamship contributed to a great expansion of global trade, communication and migration, and also to the extension of imperial power. Those benefits were uneven: the same ships carried troops, goods and labourers on terms that were often harsh. Steam also brought new dangers, such as boiler explosions and fires, which prompted regulation and inspection. Whatever one makes of those consequences, the shift from wind to engine ranks among the most significant changes in the long history of boats and ships.