1845 - Cutting-Edge Steamship Great Britain

Famous Engineer Isambard Kingdom Brunel, 39, made William Patterson & Son build at Bristol the new vessel of the Great Western Steamship Company for the purpose of transatlantic packet service. She is named Great Britain. Her commissioning was delayed by the solution of high-level engineering issues.

She displays two innovative, we may say bold, features : an iron hull and a screw propeller. She was launched two years ago, and has just started to operate her rotations across the Atlantic ocean. She is the largest ship in the world, the largest that has ever existed. She has cost £117,000, as much as the largest warships exclusive of their armament.

¤ William Patterson, who started his own business in 1830, was already the builder of Great Western seven years ago and is a close partner to Brunel.

¤ Brunel and Patterson surveyed two pioneer ships, Rainbow in 1838 as for the iron hull and Archimedes in 1840 as for the screw propeller. Yet their survey did not give Brunel and Patterson a ready-made solution. They had bold decisions to take without any sound reference.

¤ This is Patterson who reviewed Laird's framework on Rainbow in late 1838 and became fully convinced by the obious advantages of an iron hull, that Brunel endorsed. Brunel himself looked into the tricky question of the propeller with some help of inventor Francis Pettit Smith, with whom he finally quarreled. Far from imitating original Smith's propeller or from adopting his proposition of a four-blade one, he came to the original design of a six-blade propeller.

¤ The largest warship in the world is the 3,250-ton four-decker Pennsylvania of the United States of America, launched eight years ago, which is 210-foot long, 56¾-foot broad and 24¼-foot deep, carrying 130 32-pounders of different lengths. The second is the 3,100-ton three-decker Queen, launched six years ago, which is 204-foot long, 60-foot broad and 23¾-foot deep, carrying 104 32-pounders and six-68-pounders. They both displace some 5,200 tons.

The 3,450-ton ship is 322-foot long, 50½-foot broad and 32½-foot deep. She has been said to displace 3,650 tons, which seems very unlikely as very light and not concurring with the tonnage - maybe this is solely a trial displacement in a light condition? By the way, she carries 1,200 tons of coal and can carry up to 1,200 tons of cargo, the full payload being 1,300 tons. The hull weighs some 1,050 tons, and the machinery 550 tons, exclusive of 200 tons of water in the boilers - which gives 1,800 tons minimum for the light vessel. An engineering document gives a light displacement at 2,100 tons, a most plausible figure if one takes a large amount of accommodation and of furniture into account. Great Britain's full load displacement should likely be close to 4,500 tons.

The hull is strongly built, with thick frames and ten longitudinal girders. The one-inch plates are cross-lapped and double riveted. There is a double bottom in addition with five watertight bulkheads, which gives the ship the highest level of safety.

¤ An iron hull is stronger than a wooden one for a lighter weight, what Patterson acknowledged in his survey. Typically, in the standards of British shipbuilding, the wooden hull weighs between 40 and 50% of the total ship weight, the least figure relating to the largest vessels.

¤ There is a boundary for the length of a wooden hull, which is generally estimated at 350 feet. There are different reasons for that, the most important being the longitudinal bending stress which increases with length and results in flexing the hull in the form of hogging and sagging - it generates a cyclic fatigue which is destructive in the long run.

Brunel has kept conventional low pressure flue type for the three boilers - their pressure is given at 5psi above the atmosphere, which is rather low. However he has abandoned the side-lever engines for two inclined direct-acting ones. The cylinders display a 88-inch bore and a 6-foot stroke and make the shaft run at 18rpm. They deliver 1,000hp for an expected continuous speed of 10 knots. The choice of the screw propeller has delayed the ship by nine months to define an appropriate one. The ultimate screw displays six blades on a 16-foot diameter, and runs at 54rpm thanks to a gear - a chain drive to keep it as silent as possible, which is another bold decision. As for the sail plan, the ship has six masts with the rig of a barquentine.

The ship can host 360 passengers but there were 45 aboard only for the maiden voyage. On her first crossings, she was 1½ knot slower than the aces Columbia and Hibernia of the Cunard line, and one knot slower than Great Western. Moreover she rolled heavily. It created much concern with Brunel, as one can imagine. Between the first two rotations, he decided to extend the screw blades by two inches to improve speed, which proved to be an ill-fated decision. The second rotation turned to be a disaster. In a heavy weather, the ship lost a mast and three blades in six of her propeller, an finally ran aground onto the Massachusetts Shoals. Refloated, she can resume her voyage to New York with 104 passengers, rather unsettled as one can imagine. On her way back to Bristol after repairs, she lost four blades in six of her propeller, She had only 28 passengers aboard. The company is losing much money while the ship obviously requires a new refit.

Some experts foresee that the revolutionary but almost heretic ship should be fitted with sidewheels soon. May they be right?

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LINK WITH PREVIOUS CHRONICLES

1838 - Crossing the Atlantic Ocean under Steam

1839 - Archimedes, First Screw-Propeller Ocean-Going Steamship

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IN RETROSPECT FROM TODAY

Note - on Great Britain's fate.

Before the third rotation, Patterson solves heavy rolling by the addition of bilge keels He also suppresses the third mast and replaces iron rigging by a wooden one. Brunel reverts from his six-blade screw pattern to Smith's four-blade one.

In 1846, she makes two rotations at a better speed before running aground on Irish coast owing to navigational errors. Refloating her drains the financial reserves of the company, which collapses, thus she is sold to Gibbs, Bright and Co.

The new shipowners give the ship a thorough refit. The hull is reinforced at both bow and stern and stronger keelsons are set on the whole length. Machinery is changed too. The direct-acting engines are replaced by oscillating ones supplied by John Penn, of the same large size than the ones they substitute for. Steam is provided by six boilers working at 10 psi in substitution for the three working at 5. The four-blade propeller was replaced by a three-blade one. The sail plan is reduced to four masts, two of which being square-rigged, the two other rigged in barquentine. By saving internal volume, she can now carry 2,200 tons of payload. Then she resumes transatlantic rotations under this new profile.

Resold to Antony Gibbs & Sons after five years, Great Britain is refitted once again to extend the capacity to 730 passengers. The sail plan is reduced to three masts, all square-rigged. She resumes service as a packet ship to Australia from 1852 on. She serves a troop ship during the Crimean war of 1854-55, and during the Indian mutiny in 1857. Afterwards she resumes her duty on the line to Australia.

In 1882 she is converted to a sailing ship to transport bulk coal. She runs aground in the Falklands in 1886 and finishes her life as a coal bunker. Refloated, she will return to Bristol to become a museum in 1970. A very strong ship, she has survived four strandings and a very long life.

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SUGGESTED BIBLIOGRAPHY

Arthur J. Maginnis - The Atlantic Ferry - London, 1900 - available on the Internet

Direction Maurice Daumas - L'Expansion du Machinisme - Paris, 1968