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Launch of the SS GB

The eccentric engineer: Isambard Kingdom Brunel and the SS Great Britain

Image credit: User:Lordprice at en.wikipedia

This edition tells the story of how Isambard Kingdom Brunel, voted second-greatest Briton of all time, floated into the unreliable clutches of the first iron-built ship.

Engineers don’t always get the credit they deserve, but if there’s one who does it’s Isambard Kingdom Brunel, voted second-greatest Briton of all time in a BBC poll in 2002 (after Churchill). However, as with all celebrities, he also tends to get a lot of the credit others deserve, and some perhaps that no-one does.

Take the SS Great Britain – undoubtedly one of the engineering marvels of the 19th century and the first iron-built ship with a screw propeller. Commissioned by the Great Western Steamship Company from Brunel and the less-well-remembered Thomas Guppy, Christopher Claxton and William Patterson, she was originally going to be a wooden vessel like her predecessor, the Great Western.

It was by complete chance that the Great Britain was built in iron. In the winter of 1838, John Laird sailed the largest iron-hulled ship in the world, the Rainbow, into Bristol harbour, piquing Brunel’s interest. Iron was a new material for shipbuilding, but had several advantages. It was both lighter and cheaper than wood, was impervious to shipworm and rot and, most importantly, immensely strong. Wood also presented one great problem as you simply couldn’t build a ship much above 90m in length due to ‘hogging’ – the flexing of the hull as it moved across the waves. With iron, that limit disappeared, and transatlantic liners became a possibility.

Brunel dispatched his lesser-known colleagues Claxton and Patterson to take a trip to Antwerp on the Rainbow and report back. When they returned they were so impressed that the plans for a wooden hull were scrapped in favour of an iron one. Not only that, the lure of making ever bigger iron ships encouraged them to increase the size to 3,400 tonnes, over 1,000 tonnes more than any other ship in existence at the time.

The Great Britain’s other innovation came about more by luck than judgment. In the spring of 1840, another revolutionary ship appeared in Bristol harbour, the sleek steam schooner SS Archimedes. She was unique in that she was powered not by the traditional paddle-wheels, but by a permanently submerged screw propeller at the stern. This made her lighter and her engines smaller. She was also much less bulky without the huge, easily damaged paddlewheel boxes.

Brunel was fascinated and the builder and inventor of the screw, Francis Pettit Smith, flattered by the great man’s interest, agreed to lend him the ship for several months. Brunel set to work trying different screw geometries. Eventually he settled on a four-bladed design, also suggested by Smith.

Brunel borrowed that idea for the SS Great Britain, too. The paddlewheels for the ship were already half finished when he told directors of the company he wanted to change the design again, and, waving goodbye to their wallets, they agreed to the changes. By now, Brunel’s ‘ideas’ were getting expensive. The ship was nine months behind schedule and her total cost was £117,000, 40 per cent over budget, even before adding the £53,000 worth of specialised plans.

However, it had been worth it. As we all learn at school, the SS Great Britain was the first ‘modern’ ship. She was a huge success. Or was she?

The truth about her service was a little more nuanced. Having floated out in Bristol, she was due to be towed to London for fitting out, but the London docks failed to carry out the promised modifications to take such a large vessel. Eventually, the Bristol Dock Board agreed to make the changes there, but they took a year to complete, during which time the ship just sat rusting. Finally, in December 1844 Great Britain was floated out, only to jam in the lock gate.

She was five years overdue by the time she made her first crossing to New York, where the very first issue of Scientific American noted rather sniffily that she’d be better off with paddlewheels. One problem was her unexceptional speed. Brunel had replaced Smith’s screw at the last minute with his own design, and it was only after some uncomfortable crossings, in which propeller blades and masts were lost, that he reverted to his competitor’s design.

Once again, investors coughed up the money for the refit and, after her second season, she was again laid up for repairs. In her third season, she ran aground on the north-east coast of Ireland, where she remained stuck fast for a year before being floated off at a cost of £34,000. By now the investors had had enough and she was sold for just £25,000. From that point on, however, it was all plain sailing.

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