In the United States wood was very largely used, both for full-powered ships and auxiliaries, but there was no time to per mit the timber to season and they were built of "green" timber. Similarly a number of vessels of various types—lighters, tugs, tankers, etc.--were built of ferroconcrete, the rapidity with which they could be turned out compensating for their excessive weight in wartime, although only one or two of them survived more than a few months of peaceful trading.
In criticising these war built standard ships there has been a very general tendency to forget the peculiar circumstances in which they were built and the necessity of getting something that would float into the water as quickly as possible. Their utility in competitive trading in peaceful circumstances was a secondary consideration. The United States Shipping Board, a State department formed to run the tonnage so built in America, was left with a large number of ships on its hands for which no purchasers or managers could be found, but many of them have since the peace been converted to Diesel or electric power and their running expenses greatly reduced.
From the very early days of regular ser vices, the older and smaller units of the various companies were put on intermediate services at reduced prices, and these ships gradually came to be known as cabin class ships. Very few ships were specially built for the class until 1914, when the Canadian Pacific Line commenced a long series with the "Metagama" and the "Missanabie," ships with a gross tonnage of about 12,500 and speed of 16 knots, having accommodation for 52o passengers in the cabin class, paying a fare approximating to the second class fare in the bigger ships, and 1,200 in the third class. Since then the type has been taken up enthusiastically by various com panies, particularly on the North Atlantic, until the present de velopment is the "Duchess of Atholl" and her sisters, also owned by the Canadian Pacific Line, having a gross tonnage of roughly 20,00o, a sea speed of 17 knots and single reduction geared turbines supplied by oil fired high-pressure boilers which give the remarkable economy of 0.64 lb. of oil fuel per s.h.p. per hour for all purposes.
There has. been a noteworthy tendency to build fast cargo liners since the war, ships with a sea speed of 14, 15 and 16 knots, but carrying cargo only to regular schedule. Both steamers and motor-ships have been built for these services and have found great favour with shippers. Great economy in running has been obtained with the result that they have secured a considerable proportion of the trade which was formerly carried by tramp steamers.
In steamers this remarkable economy has been made possible very largely by the employment of high pressure steam. The Clyde passenger steamer "King George V.," built by Messrs. Denny in 1926 in conjunction with Messrs. Yarrow, the boilermakers, and the Parsons Steam Turbine Com pany, had the first noteworthy installation apart from unsuccess ful experiments made half a century ago. She was a steamer of 791 tons gross, burning coal under water-tube boilers working at a pressure of 55o lb. to the square inch with the steam tempera ture raised to a maximum of 75o degrees Fahrenheit. This ship considerably exceeded her contract speed of 20 knots on trial and has proved a success in many ways, particularly with regard to economy. But numerous adjustments and alterations have had to be made since her launch.
In modified form high pressure steam has resulted in very con siderable economies, both in fuel consumption and weight.
Although no steamer has yet been built with anything approach ing the 55o lb. of the "King George V.," the general tendency is to increase the pressure both for naval and for mercantile work and 400 lb. is becoming quite usual.
The White Star Liner "Oceanic" of 1871 was the first of the modern type of express luxury liner, which attracts more attention than any other type, but which can exist economically only on the direct service between Europe and the United States. The White Star Line had then just been founded for the purpose of engaging in the Australian trade, and for that purpose had bought the name and houseflag of one of the most famous of the clipper ship companies. Events had caused the directors to change their intentions and the first ships were put on service between Liverpool and New York, the "Oceanic" being the pioneer. These ships differed very materially from the accepted type of screw steamer, having over ten beams to their length and being designed on the somewhat revolutionary lines advocated by the late Sir Edward Harland of Messrs. Har land and Wolff, the Belfast shipbuilders. The tonnage of the "Oceanic" was 3,707 and while she was fully rigged as a 4-masted barque her single screw engines gave her a sea speed of
knots, and she proved herself an unqualified success after being generally condemned on theoretical grounds by the experts. Three years later the "Germanic" and "Britannic," the latter still afloat as a Turkish Government ship, were built with a gross tonnage of 5,000 and speed of 16 knots.