Material marvels: SS Great Britain

Materials World magazine
,
30 Apr 2017

Khai Trung Le talks to the SS Great Britain Trust on the legacy of the namesake ship, its engineering influence and its heritage in British shipbuilding.

The SS Great Britain is a ship of many firsts, and again not. It was the largest iron-wrought steamship, the first large screw-propelled ship and the first transcontinental ship designed to operate on a timetable. At the same time, with so many qualifiers, that can seem an underwhelming list – the first iron steamship was the Aaron Manby, completed in 1822, the first screw-propelled steamship was the SS Archimedes, and the first steamship to sail the Atlantic was the SS Savannah. But such single-minded focus would be to overlook the Great Britain’s history and innovations that would define shipbuilding and British engineering ingenuity for generations.

London to Bristol via New York

The spark to propel Isambard Kingdom Brunel into shipbuilding reportedly began during a meeting with the Great Western Railway board of directors in 1835 regarding the cost and timescale of the railway project. Simon Strain, Active Interpretation Manager at the SS Great Britain Trust, said, ‘Brunel made a quip saying, if the company really wanted to extend its fortunes, they should consider extending the railway from London to Bristol to New York via steamship. This by all accounts was the genesis of what would become the Great Western Steamship Company.’

Brunel’s first ship, the SS Great Western, was a timber-built, copper-bottom paddle steamer. Although relatively conventional in design, it was further proof-of-concept for a steam-powered Atlantic crossing and plans for a sister ship soon followed. The initial concept was for another wooden paddle steamer, but it underwent costly and lengthy redesigns as Brunel found inspiration from vessels visiting Bristol – John Laird’s English Channel packet ship Rainbow, at the time the largest iron-hulled ship in service, and later again as Brunel paused construction on the Great Britain to charter the Archimedes for a month and analyse the advantages of the screw propeller.

Although the Great Britain was not the first iron ship of its time, the magnitude of Brunel’s vision deserves recognition. Iron was becoming increasingly more affordable, compared with wood, is not susceptible to dry rot, and provides greater structural strength, enabling the Great Britain’s gargantuan size – by the fifth draft, the ship was 1,000 tonnes larger than any other ship in existence. The hull comprised wrought iron rivet plates on wrought iron frames, and repeatedly stood the test of time. Nick Booth, Head of Collections at the Trust, said, ‘When she ran aground in Dundrum Bay [in 1846] and was there for more than a year, she only really survived because she was made of iron,’ and similarly attributed the iron hull for the ship’s constitution, leading up to its successful return and restoration in Bristol.

Screw propellers bypass some of the most prominent shortcomings of side paddles. Whereas paddles often emerge from the water as the ship is buffeted by waves, the propeller remains under the water line, making it easier to maintain a straight course and reduce wasted fuel. Over time, the SS Great Britain’s defining features would be changed or removed according to its uses. While some moved away from the early innovations of the ship – the iron cable rigging was replaced with conventional hemp rigging, and the ship was converted from a steamship with auxiliary sails to a sailship with an auxiliary engine – the screw propeller remained a constant. Luke Holmes, Interpretation Officer at the Trust, said, ‘At the time, the propeller was still a largely untested technology at that scale. Due to the coldness of the ocean water, the iron would become fatigued, repeatedly expanding and contracting until it deformed and broke. But as the screw propeller became more popular, and design and manufacturing processes caught up, it became a developed technology. The Great Britain propeller got several upgrades in its lifetime, with the two-blade propeller the most successful.’

However, with numerous delays owing to the Great Britain’s redesigns, a shortage of initial passengers and, perhaps most damning, the Great Western Steamship Company’s decision to build the ship’s engine internally against Brunel’s advice, the cost of refloating the ship after being run aground in Dundrum Bay, Northern Ireland, in 1846 bankrupted the company. Following purchase by Gibbs, Bright & Co, the ship was adapted to a clipper in 1852, carrying emigrants to Australia, and its original 1,000 horsepower engine was replaced with an auxiliary engine. It was again repurposed into a windjammer in 1882, carrying cargo between England and the USA, before being beached near Port Stanley, Falkland Islands, in 1937.

While the Great Britain took on many roles and forms, Strain sees this adaptability as demonstrative of the ship’s inherent qualities. ‘Modern ships have a working life of 15–20 years. The Great Britain, an experimental ship, was in service as a passenger ship for around 30. Plus a couple of years as a cargo ship, and another 30 as a floating warehouse. It’s a testament to how well built and designed she was that she could be repurposed in so many different ways.’

Isambard

It is impossible to separate Isambard Kingdom Brunel, now widely celebrated as one of the UK’s greatest engineers, from the innovations and accomplishments of the SS Great Britain. But his obituary in the September 1859 issue of The Engineer suggests that the universality of praise is a recent phenomenon. Highlighting the ‘imperfections of his character and the disadvantages of his peculiar temperament’, the obituary noted within his career ‘a class of disappointments […] of the financial results of the vast sums of money the expenditure of which he controlled, Mr Brunel was almost uniformly unsuccessful’. The Engineer proceeded to query ‘in what respect many of his projects have advanced the practice of engineering’ save for their magnitude.

Holmes concedes that Brunel was a superior structural, rather than mechanical, engineer, and believes Brunel was propelled by an almost idealistic optimism – ‘he’s not worried about the obstacles and criticisms, mere mechanic obstacles shouldn’t stand in the way of innovation’ – pointing to Brunel’s thoughts surrounding the placement of the rudder as an indication of his forward-thinking mindset. ‘It might seem silly, but putting it behind the propeller was quite important. It helped drive the ship and made it easier to steer, whereas people had suggested putting the rudder forward of the propeller, which would’ve made the ship incredibly clunky.’

Estimated journey length – 84 years

The SS Great Britain returned to Bristol in 1970 – officially 84 years after beginning its final voyage in 1886 – and the Trust began working with conservation researchers from the University of Cardiff, UK, on the best methods of preserving the ship. Booth noted, ‘When she was brought back, she was just a hull and maybe a first class cabin toilet. For a while, she was treated as a ship and repeatedly cleaned out, sanded and painted, but we knew we would slowly start to strip the hull. So the decision was made to treat her like a museum ship.’ The successful preservation of the Great Britain is owed in part to the dry dock that simulates the ship being afloat but allows control of the humidity around the hull. ‘Cardiff’s proposal included the dehumidifiers and the glass sea above the dry dock to help keep the air in, and the shallow water keeps our energy costs down. If we had done nothing, the hull had around 30 years left in her,’ Booth added. 

Conservation efforts have involved grants from the National Heritage Memorial Fund, the Headley Trust and Rolls-Royce and today, after inspiring a generation of engineers, the SS Great Britain continues to serve since its reopening as a museum ship in 2005 at the Bristol docks.