As the Chief Engineer of the Great Western Railway Company, Brunel persuaded his employers to let him build a steam ship to travel from Bristol to New York. His first effort, the Great Western, made its first voyage to New York in 1838. At that time the largest steamship in existence was 63 m (208 ft) long, whereas the Great Western was 72 m (236 ft) long. The journey to America took fifteen days and over the next eight years made sixty crossings.

The next steamship that Brunel built in Bristol was the ss Great Britain. At the time of her launch in 1843 she was by far the largest ship in the world, over 30 m (100 ft) longer than her rivals, and the first screw propelled, ocean-going, wrought iron ship. She was designed initially for the Trans-Atlantic luxury passenger trade, and could carry 252 first and second class passengers and 130 crew. She is widely recognised as one of the technological fore-runners of much modern shipping and exemplifies the industry and inventiveness of the Victorian era.

She was immediately successful - on her maiden voyage across the Atlantic the ss Great Britain easily broke the previous speed record. Although effectively a prototype, she continued sailing until 1886, and travelled thirty-two times around the world and nearly one million miles at sea.

The Engine Room is dominated by the three storey high steam engine of 340 tons whose components are moving and turning. It produced 1,000 horsepower, and the four 2.3 m (88 in) diameter cylinders were set low in the hull and arranged in a V-formation, two on either side, at thirt three degrees to the vertical.

They drove a crankshaft - then the largest forged object in the world - which was set high up in the engine space. The crankshaft carried a wooden toothed chain wheel, 5.6 m (18ft 3in) in diameter, between the two sets of cylinders. This chain wheel used four chains weighing seven tons to turn the smaller 1.8 m (6 ft) diameter lower chain wheel attached to the propeller shaft.

As the engine turned the crankshaft at 18 rpm, the propeller shaft turned at 53 rpm (a gear ratio of 2.95:1), propelling the ship at 12 knots (around 22 kmph). The 1,000 horse power (745kw) engine is the equivalent today of the 70,000 horse power (52,000kw) Rolls-Royce Olympus engine.

The steam used by the engine was produced from sea water in the world's largest boiler at the time, holding 200 tonnes of water. The furnaces under the boiler were fuelled by coal (the ship could carry 1,200 tonnes) which was shovelled by a gang of stokers into 24 stoke holes. The stokers worked in shifts to ensure a constant supply of heat. The engine room would have been an awe-inspiring sight - loud, filthy and monstrous.

In 1846, the Great Britain was stranded by a navigational error and was sold for salvage. After repair, she carried thousands of immigrants to Australia until converted to sail in 1881. Three years later, Great Britain was retired to the Falkland Islands where she was a warehouse and coal hulk until she was scuttled in 1937. In 1970 an ambitious salvage effort brought her home to Bristol, where today she is conserved in the dry dock where she was originally built. The museum won the prestigous Gulbenkian Prize in 2006 and was named England's Visitor Attraction of the Year in 2007.