Paddle Wheel Steamers

At the end of the nineteenth Century steam expansion was taken one stage further and a few quadruple expansion engines were built for marine use, but their employment was strictly limited.

Twin Screws.

In 1862 the first full-powered twin screw steamer, apart from certain experiments in the very earliest days of steam, was built on the Thames. She was the 400-ton "Flora" and although her builders, Messrs. Dudgeon, made a speciality of twin screw steamers and built the far larger "Ruahine" in 1865 for the Panama, New Zealand and Australian Royal Mail Company, the idea did not attract the liner companies until the "Notting Hill" of 188r proved the advantages of the system on the North Atlantic. Even so the single screw was not aban doned at once and as recently as 1896 first class liners were built with one shaft only, in spite of the uneasiness caused by several serious accidents.

As the power of ships increased the danger of broken shafts was multiplied, and triple and quadruple screw ships came into being at a later date, although serious disadvantages were in volved.

Turbine Ships.

The experimental "Turbinia," built at Wall send on the Tyne in 1894 and given turbine engines invented by the Hon. Charles Parsons, revived one of the earliest prin ciples of employing power and proved that it was capable of being used at sea. Her dimensions were 10o feet by 9 feet beam by 3 feet draught, her displacement being tons. The original machinery installation consisted of three steam turbines, totalling 2,000 shaft horse power and each driving a shaft carrying three screws in order to overcome the disadvantages of high propeller speed. During the Diamond Jubilee Naval Review of 1897 she was taken down to Cowes secretly and suddenly dashed out among the assembled ships at what was then the astounding speed of 344 knots. Naturally she caused a great sensation and the Admir alty built two turbine-engined destroyers which unluckily came to grief, the one by stranding and the other owing to her light construction. There was a tendency to blame the machinery, which had nothing to do with either mishap, and it was some time before Mr. Parsons could persuade commercial shipowners to take an interest in his invention.

The "King Edward" of 1901 was the first merchant steamer to be given turbine machinery, a Clyde passenger steamer which is still running after material alterations. She was followed by the cross Channel packet "The Queen" of 1903 which proved herself greatly superior in speed and far more economical than the paddlers which had preceded her on the service between Dover and Calais. The next important ships to be built on this system were the Allan Liners "Virginian" and "Victorian" of 1904, ships of about 10,750 tons gross each with a trial speed of nearly 20 knots. With all these ships there was a certain amount of trouble in the early days, but the turbine made steady progress and proved its reliability in the Cunard Liner "Carmania" (19,566 tons) of 1905, which is still running with her original machinery and whose success resulted in the turbine being adopted by the Cunard steamers "Mauretania" and "Lusitania " which were the biggest and fastest liners in the world when they were built in 1907. In 1928 the "Mauretania" still held the Atlantic

record which she lowered in 1910.

The 224 oot steam launch "Charmian" was the first vessel in which intermediate gearing between the turbine and the pro peller was tried, the experiments taking place on the Tyne as early as 1897 and being practically contemporary with similiar experiments carried out on the Continent. It had long been realised that the efficient speed of the turbine was far too great for the propeller, which was the reason why multiple screws were fitted to the shafts of the early passenger steamers. In 1909 these experiments had produced sufficient promise to war rant the cargo steamer "Vespasian" having her old triple expan sion engines taken out and turbine machinery with single reduc tion mechanical gearing substituted. The great increase in speed and economy which was immediately obtained drew attention to the possibilities of the turbine for cargo as well as fast passenger vessels, and from this it became evident that the gearing, whether it was single or double reduction, was of the greatest advantage even at the maximum speed so that the direct coupled turbine is now regarded as obsolete at sea. Other experiments have been made with hydraulic gearing of the Foettinger and other prin ciples to obtain the same result, while many regard the electric drive, which is described below, as being little more than another form of gearing.

In the "Otaki," a triple screw cargo steamer built for the New Zealand Shipping Company in 1908, Messrs. Denny of Dumbarton the shipbuilders, co-operating with the Parsons Steam Turbine Company, made a successful effort to combine the ad vantages of the turbine and reciprocating engines. This ship was given a triple expansion engine on each of the two wing shafts, the steam exhausting from them into a low pressure turbine on the centre one. In competitive trials with two ships of similar hull design but more normal engines she averaged a knot greater speed with eleven per cent less coal consumption, although for a cargo vessel the interruption of the after holds by the three shafts was recognised as a serious disadvantage.

For passenger steamers the system promised even greater economy and was later fitted into several large liners, notably the White Star steamer "Olympic" (built 1911, 46.439 tons gross) with conspicuous success.

After the war the same idea was put forward by German ,engineers in the Bauer-Wach system, in which the disadvantages of the three shafts are avoided by placing the turbine directly abaft the reciprocating engines on the same shaft, with a clutch which disconnects it automatically when it is desired to manoeuvre. An economy of 15 per cent and more has been proved possible with this system, which is particularly well suited for cargo ships and which is being installed in a number of existing vessels just as compound engines were converted into triple expansion in the 'eighties and 'nineties.