The development of steam power in the 18th century was arguably one of the most important changes of its age. Steam engines, and the promise of the tireless power they offered, transformed Western society, as production moved steadily from the village workshop to the urban factory.
Shipbuilding, too, was part of this revolution, with the Royal Naval Dockyards in Britain being early adopters of the new technology. Steam power was used to pump out dry docks and power sawmills. In 1802, Marc Isambard Brunel (father of the famous civil engineer) was authorized to install steam-powered machinery for making pulley blocks at Portsmouth Dockyard. The block mills would be capable of producing 130,000 rigging blocks a year.
Yet, while warship production was increasingly powered by steam, the ships themselves remained largely untouched by the new technology. The fleets that fought at Trafalgar in 1805 still were powered by wind alone.
As early as 1630, English engineer David Ramseye was granted a patent for a steam engine designed to propel a barge, but such early attempts were unsuccessful. The first steam engines were inefficient, with a low power-to-weight ratio. This wasn’t such an issue when they were used on land, but it made them impractical for marine use. Only after the 1760s, when the British pioneer James Watt made a number of improvements to boost the power output of the new technology, did steam become a practical proposition.
In 1776, the Marquis de Jouffroy, a French inventor, used one of Watt’s engines to power a boat driven by rotating paddles modeled after the webbed feet of ducks. Other early pioneers tried different forms of propulsion. In 1787, James Rumsey of Virginia built a jet-propulsion steamer that used a pump to force water from the vessel’s stern. In the same year, John Fitch of Pennsylvania fitted a boat with paddles, six on either side, driven by a 12-inch steam cylinder. The paddles mimicked the way Native Americans propelled their canoes.
But in the view of most observers, these novel forms of propulsion were not the answer. It was the numerous water mills that still dominated the 18th-century landscape that signposted the way forward. They used the push of running water to turn a large paddle wheel and power the mill. Shipbuilders realized they could reverse this well-understood technology by using a steam engine in a boat to make a paddle wheel push against the water. This form of propulsion was used in the first successful commercial paddle steamer, the Charlotte Dundas, in 1801. Built by Scottish engineer William Symington, she was a 60-foot steam launch with a rear-mounted paddle wheel that operated towing barges on the Forth and Clyde Canal.
Over the first half of the 19th century, the number of paddle steamers in commercial use multiplied, some, like the Charlotte Dundas, powered by rear paddle wheels but most adopting a wheel on each side mounted amidships. Steam power proved particularly important in North America, where it was used on the continent’s extensive river systems. In 1807 American inventor Robert Fulton used an imported Watt engine to power his North River Steamboat, more commonly known as the Clermont; she provided North America’s first commercial service, steaming on the Hudson River between New York City and Albany. In 1819 the American ship SS Savannah became the first steamship to cross the Atlantic using a combination of steam and sail.
The first application of steam power in a warship also came from Fulton. During the War of 1812, he proposed the construction of a paddle-wheel steam frigate for the U.S. Navy, designed with the specific purpose of breaking the Royal Navy’s crippling blockade of New York. The Demologos, later renamed the Fulton I, was completed too late to be tested in action. The vessel was unsuitable for use in the open sea, so she remained in New York Harbor and was visited by naval strategists from around the world.
The Royal Navy in particular was interested in the possibilities of paddle steamers. The service’s first ones were modest in size and used for dredging harbors and towing sailing warships, but by 1827, the Admiralty was prepared to order the world’s first seagoing steam warship, the 700-ton HMS Dee. The success of this vessel led to a steady increase in the number of paddle wheel–driven warships.
As steam power became more prevalent, some marine engineers began to question whether paddle wheels were the most efficient means of propulsion. They might churn the water in an impressive way, but for much of the wheel’s cycle the paddles either were pushing water downward or lifting it up. Only at the very bottom was water being driven directly backward.
Another issue was that paddle steamers performed best in calm water. This made them suitable for rivers and canals, but less so for the open ocean. As a ship rolled in a heavy sea, one paddle wheel might be fully submerged while the other was lifted clear of the waves, placing huge strain on the vessel’s engine. Furthermore, changes in a steamer’s draft as cargo was loaded and taken off or coal in its bunkers was consumed also could affect the efficiency of paddle wheels by either raising them too high or submerging them too deep. What was required was an alternative means of propulsion that was permanently underwater.
The obvious alternative to the paddle wheel was a propeller. This idea was not new, deriving from the Archimedes screw, an ancient Greek method for pumping water. Numerous engineers on both sides of the Atlantic independently came up with essentially the same solution. The British engineer Edward Shorter demonstrated a working propeller in 1800. Using eight men turning a capstan, he was able to move the small ship Doncaster across Gibraltar Harbor at one and a half miles per hour. Four years later, an American, Colonel John Stevens, demonstrated a small propeller-driven steam launch in New York Harbor.
Many early design improvements were the product of luck rather than science. In 1837, British inventor Francis Pettit Smith was demonstrating a steam launch driven by a single-threaded screw propeller with two complete twists (resembling part of a large corkscrew). During one of his trips, half of the wooden propeller broke off, and to the surprise of the crew, the speed of the craft immediately increased. Thanks to advances such as this, propellers soon were being tried on seagoing ships.
The Royal Navy was particularly interested in propeller technology. Many naval officers were uneasy about the tactical implications of a warship’s motive power coming from large paddle wheels mounted on the sides. Not only did they mask much of the main armament, which was still mounted in broadsides at this time, but they also would be very vulnerable to damage from enemy fire. Replacing these wheels with a propeller mounted beneath the surface would solve both problems. The only question was whether the propeller was actually more efficient than the paddle wheel, as the former’s supporters claimed. Unfortunately, this was a question that early Victorian science was incapable of answering. But the Royal Navy had a time-honored method for resolving such matters: a tug of war.
The ships selected to decide the issue were a pair of steam frigates of similar size currently being built. Both were powered by the same engine design. HMS Rattler was adapted to take one of the new propellers, while HMS Alecto was fitted with traditional paddle wheels. In March 1845, the ships were put through their paces. The first test was a race of more than a hundred miles, which the Rattler won comfortably. Next came the tug of war. The frigates were tied stern to stern and then both steamed off in opposite directions. With the two ships at full power, the Rattler was able to demonstrate her considerable power advantage by pulling her rival along at almost three knots. The Admiralty was convinced—and the propeller was here to stay.