Claxton and William Patterson, a local shipbuilder, toured the main steam ports of Great Britain and sailed on every coastal and channel steamboat line. ‘Great improvements are being gradually introduced,’ they reported in January, ‘more particularly observable in the Clyde than elsewhere.’ For crossing the ocean, they recommended a much larger steamship than any yet built. They invoked a common principle, well known to shipbuilders of the time: that a vessel’s resistance as it moved through the water did not increase in direct proportion to its tonnage. As a measure of interior space, tonnage was computed from three dimensions. Resistance was then estimated from just two dimensions, the width and depth of the hull. Thus tonnage increased as the cube of the dimensions, resistance only as the square of them. A much larger ocean ship could therefore include the necessary space for coals and machinery, well beyond the capacity of a conventional ship, without requiring intolerable increases in power and fuel consumption to maintain adequate speed. Claxton and Patterson estimated that a steamship of 1200 tons and 300 horsepower, loaded with 580 tons of coal, would average between six and nine knots and cross the Atlantic in less than twenty days to the west, and just thirteen days to the east: roughly half the average voyages by sail.
The Great Western Steam Ship Company first planned to build two ships of that size, then decided on a single larger vessel of 1400 tons and 400 horsepower. Patterson – ‘known as a man open to conviction,’ according to Claxton, ‘and not prejudiced in favour of either quaint or old-fashioned notions in ship-building’ – would build her in Bristol. As managing director of the new company, Claxton looked after day-to-day operations. The building committee of brunel, Guppy, Claxton and Patterson met about once a week, whenever railway business brought brunel to Bristol. In general, on this committee Patterson took charge of the ship, brunel of the engine. ‘Mr. Patterson drew the lines,’ Claxton later recalled; ‘Mr. brunel, Mr. Guppy, and myself, often sat over them; Mr. Patterson got instructions and made his own calculations accurately; Mr. brunel made his also often by my side.’ Over the next two years, they planned and built the largest steamship yet, the first designed for regular crossings of the North Atlantic.
They were racing against a competing group in London organized by Junius Smith, an expatriate American businessman. His British and American Steam Navigation Company drew investors from both sides of the ocean. This final sprint to steam across the Atlantic came down to three separate but overlapping rivalries: Britain against America, Bristol against London, and the Clyde against the Thames (or the North against the South). Subtly complicated and multiply crosshatched, the contest was played out amid fierce regional loyalties for rich stakes of prestige and fortune.
The crucial technical questions involved engines and boilers. The two leading British builders of marine steam engines were Robert Napier of Glasgow and Maudslay, Sons and Field of London. (Clyde and Thames.) After Marc brunel’s old friend Henry Maudslay died in 1831, the firm had passed on to his sons, Thomas and Joseph, and in particular to Joshua Field, a skilled engineer and manager. ‘No vessel ever had a sufficient power yet,’ Field had declared in 1822. ‘There is a limit, but that limit has never yet reached its fullest extent.’ As horsepowers kept on growing, the upper border was continuously extended. Progress already seemed infinite. By the 1830s, both Napier and Field were intrigued by the potential honour of powering the first true Atlantic steamship. ‘I have not the smallest doubt upon my own mind,’ Napier wrote in 1833, ‘but that in a very short time it will be one of the best and most lucrative businesses in the country.’ ‘The distance is limited,’ Field added a few years later, ‘only by the quantity of coal she can carry.’
By then both Scottish and English engineers had settled on the side-lever engine as the best mechanism for an ocean steamship. Derived from Watt’s old overhead beam engine, it placed the main weight of the power source at the bottom of the ship, lowering its centre of gravity to limit rolling and pitching in heavy seas. A vertical engine cylinder drove a horizontal beam pivoted in the middle, with tandem connecting rods at its ends running downward to side levers, which drove a crank on the paddle shaft to turn the paddles. It was complicated and inefficient, moving massive weights up and down, with each stroke coming to a dead stop and then reversing. The bulky rods and levers added weight and took up precious cargo space. But the various parts were easily accessible and well balanced, minimizing friction and strain and needing less lubrication than other engine types. The piston’s long stroke made full use of steam in the cylinder. Confined to the ship’s closed hold, it was protected from foul weather and did not interfere with sailors moving about on the deck. Napier changed the framing from cast to wrought iron, making it lighter and stronger. The side-lever engine was considered exceptionally rugged and reliable, important qualities for crossing 3000 miles of ocean.
The earliest marine boilers were kettle types, simply a drum of water heated by an external fire. Around 1830, Maudslay and others introduced a variation on the locomotive boiler, featuring an internal furnace that expelled its exhaust gases through long, narrow flues, making fuller use of the heat to produce more steam. But steamship boilers remained primitive and inconsistent, box-shaped and riddled with fragile seams. Each engine builder made his own boilers, using construction methods and metals of unpredictable quality. No one as yet dared push a seagoing boiler beyond a modest pressure of about five pounds per square inch. Lower pressure held down horsepower and made the engine use more coal, which limited the ship’s range and cargo capacity. More than any other technical factor, the state of boiler technology was keeping steamships off the Atlantic.
Several steamers had already crossed the ocean, but not under continuous power or as part of a regularly scheduled service. The American vessel Savannah went from the United States to England in 1819, steaming only for about eighty-five hours of the twenty-seven-day passage. Over the next fourteen years, at least five other steamships made an Atlantic crossing, down to the Scottish-Canadian Royal William in 1833, Samuel Cunard’s first venture into steam navigation. None of these ships could carry enough fuel to steam all the way. In any case, the salt water’s scaly deposits in the boilers had to be blown off or laboriously chipped out with hammer and chisel at frequent intervals; that meant stopping the engine for up to a day and proceeding under sail until the puny boilers could be cleaned, refilled, and get up steam again.
One possible solution to these fuel and boiler limitations was to reduce the route across the ocean. The shortest great circle course between Europe and North America ran just 1900 miles between Valentia, at the southwestern tip of Ireland, to St John’s, Newfoundland. The run from there to Halifax brought the total to 2400 miles. In 1824 a group in London under Maurice Fitzgerald, the knight of Kerry – an Irish statesman and member of Parliament – launched the Atlantic Steam Navigation Company to carry traffic from London to Valentia to Halifax to New York. The company included Alexander Nimmo, a government civil engineer who was building piers and harbours along the Irish coast, and other men of influence. They planned steamships of 1000 tons, almost twice the size of any vessel then afloat. In the autumn of 1825, American newspapers declared it ‘almost certain’ that the service would start in the following spring. But it never did. In these years, just before the railway, the journey by coach and steamboat from London to Valentia took fifty hours, and forty hours from Liverpool. The whole trip would have