The Ma Robert is said to have been the first steel steamer ever built; she was constructed by Laird’s for the Livingstone expedition to the Zambesi. High tensile steel was used with a limit of elasticity of about twenty-three tons, which is very similar to the metal used in the Mauretania and Lusitania where stresses are to be met. Strength and lightness were essential in the Ma Robert and therefore the new material was used. The little vessel was 73 feet long, 8 feet wide, and 3 feet deep, and was flat-bottomed and of very little draft. But the hull corroded badly and leaked very much, and the steamer came to grief on a sandbank in the Zambesi.
The Rainbow, built of steel plates in 1858, was a smart, handsome paddle-boat, schooner-rigged, and carrying two very tall masts. She had a high-pressure engine and her steam-pipe emitted the energetic snort which was peculiar to the locomotive of the time. Indeed her high-pressure machinery made such a noise that she could be heard from one side of the Mersey to the other. She was intended for the Niger Exploration expedition, and on her trial attained a speed of between twelve and thirteen miles an hour. She was 130 feet long by 16 feet beam. Although her plates were only one-eighth of an inch thick she had the stiffness and rigidity of a strong ship, and there was almost an entire absence of vibration from the engines. Her boilers, which were of puddled steel plates, were proved up to 200 lb. on the square inch, though they were only worked at 50 to 60 lb. The engine was of 60 nominal horse-power, working up to 200 indicated. The hull was divided athwartship and longitudinally by bulkheads into ten or twelve water-tight compartments.
It must be remembered that these experimental steel boats were intended for inland navigation, and being taken to Africa were withdrawn from the observation of practically every one who was competent to judge of the relative merits of iron and steel. Certainly no one attempted to build a steel boat for the ocean for some years afterwards, and it was not until 1875, when the Admiralty, acting upon observations made in the dockyards of France where steel was being used, represented to British manufacturers the importance of improving the quality of steel, that the Siemens-Martin process was brought out, and in consequence two cruisers were constructed of steel produced in this way.
The “Britannic” (White Star Line, 1874).
The “Umbria” and “Etruria” (Cunard).
With the launching of the Rotomahana, an ocean steel steamer of 1777 tons gross built by W. Denny and Bros. in 1879 for the Union Steamship Company of New Zealand, the iron age of the steamer may be said to close and the age of steel to begin. It has been shown how iron slowly but surely replaced wood in construction; when the superiority of steel to either had been practically demonstrated the change from iron to steel was rapid. In 1891 over 80 per cent. of the steam-ships under construction were of steel.
The Rotomahana was followed in 1881 in the transatlantic trade by the Allan liner Buenos Ayrean. The Allan Line has always been to the fore in the provision of first-class steamers. They were the first to have a steel ocean steamer; the first to adopt bilge keels on vessels, the Parisian in 1884 being fitted with them; and they were the first to make the experiment with turbine-driven steamers for ocean traffic in the Victorian and Virginian in 1903. These two vessels are 540 feet in length by 60 feet in breadth, and 40 feet 6 inches in depth. They are of 12,000 tons register, and have a speed of 17 knots. Besides these, the company has five twin-screw boats of tonnages ranging from 9000 to 11,000 tons, and twenty-two screw boats from 3000 to 5395 tons.
The Cunard Line’s first steel steamer was the Servia, built by Messrs. J. and G. Thomson, and completed in 1881. She was 515 feet in length, and of 7392 gross tonnage, and her engines, of 10,000 indicated horse-power, gave her a speed of 17 knots. Incandescent electric lamps were fitted in her, she being the first of the fleet to carry them. The Aurania, of slightly less length, but of equal speed, and also of steel, was built in 1883. After her came the Umbria and Etruria, steel single-screw steamers, with engines of 14,500 indicated horse-power, giving them a speed of 20 knots. The sisters Campania and Lucania, steel twin-screw vessels of 12,952 tons, were added for the New York trade, and later the Caronia and Carmania. They were sisters except in their engines; the latter being the company’s first turbine experiment, and having triple propellers. They are each 675 feet in length by 72 feet 6 inches beam, and 43 feet 9 inches moulded depth.