Special Types of Power Ships

In 1872 the Red Star Line of Philadelphia started a new sys tem by having the steamship "Vaderland" of 2,748 tons built by Palmers on the Tyne with the idea of carrying a large cargo of oil in bulk in addition to her passengers. All the authorities were against this scheme on grounds of safety, and she was used for passenger and cargo only, as were also the "Nederland" of 1873 and "Switzerland" of 1874 which were designed on similar lines. This prohibition of the carriage of oil in passenger vessels exists to-day.

In 1879 Nobels, who have already been noted for their work in building the pioneer motor and electrically driven ship, built a number of tank steamers to carry oil on the River Volga and attained considerable success with them. These steamers attracted some attention at the time, but the idea that oil would be safer in a sailing vessel than a steamer was still generally held and in 1886 the sailing ships "Andromeda" and "Crusader" were fitted with cylindrical tanks on an improved system for the purpose. Their designers attained a considerable measure of success in making their tanks oiltight, but in the same year the firm which is now Messrs. Armstrong Whitworth and Company and which still makes a speciality of tanker construction, designed and built the first real tank steamer on modern lines.

The "Gluckauf" had a deadweight capacity of 3,00o tons and a speed of 10 knots, her engines being placed right aft for safety as is still almost invariably done in tankers. Her hull was sub divided into tanks and arrangements were made for pumping them on a principle which is still used.

Since the war a large number of tank steamers have been built, although it is one of the most difficult trades to cater for and to maintain. In spite of numerous experiments it remains almost invariably a one-way cargo, so that the ship has to be exceedingly economical on account of the return journey in ballast. A large cargo is desirable for the ocean route and 13,0o0 tons deadweight and more is now quite a usual size, while the speed seldom exceeds eleven knots. On account of their tremendous length and unequal strain, the design of these tankers involves very careful considerations of strength and the majority of modern types are built on the longitudinal system, with great attention paid to fore and aft stresses.

Packet Steamers.

When the screw superseded the paddle for overseas work, the older fashion survived in the excursion steamers round the British coast, where shallow draught was generally necessary to get alongside the piers, and in the cross Channel services. The growing Continental trade and the limita

tions in draught imposed by the French and Belgian harbours brought the paddle packet steamer to a high pitch of perfection in the last days of the 19th century, ships of well over 2,000 tons gross with a speed of 22 knots and excellent seaworthiness being built in considerable numbers, mostly on the Clyde. No more of these big cross Channel paddlers were built after the turbine had proved its possibilities, but many other steamers propelled in this way, much smaller and rather slower, were built for the various excursion routes in the summer. Most of these again were ex cellent sea boats and were able to perform valuable minesweep ing service during the war.

In the United States, however, where the huge inland water ways favour the side wheel, the paddle steamer has been brought up to its highest state of development. The biggest ships of this type in the world are the "Greater Buffalo" and "Greater Detroit," built in 1923 for service on the Great Lakes, each having a gross tonnage of 7,793 and being driven by three cylinder compound engines.

Standardised Ships.

In the early days of the World War mercantile construction was almost completely suspended in Great Britain, Germany and France in favour of warships, but it received a great impetus in the United States. When the Ger man submarine campaign caused an acute shortage of tonnage it had to be resumed in an intensified form in Britain, while from 1917 the Americans launched a shipbuilding campaign unpre cedented in the history of the industry. In order to save time and money wherever possible, standardised shipbuilding came into vogue. It had existed within certain establishments for many years, the German yards particularly specialising in cer tain types and turning out large numbers of sister ships for various owners. During the World War, however, it was carried right through the various countries and in some cases the inland steel works, usually employed on bridge construction and the like, were utilised for fabricated ships with lines as straight as possi ble which were only put together and launched in the shipyards. Owing to the difficulties of supply many of these standardised ships were given machinery unsuited for their type and the con struction of the hull was frequently hasty, so that they have found themselves severely handicapped in competitive trading since the Armistice.