The “Monitoria.”
The “Iroquois” and the “Navahoe.”
Two oil-tankers, the Paul Paix and Gascony, have been built by Messrs. Craggs and Sons on this system. One of them grounded off Calais with a cargo of oil or benzine on board, and on being dry-docked for examination was found to have no damage to her plates whatever. All the steamers built on the Isherwood plan have a marked absence of vibration even when running light.
The corrugated steam-ship Monitoria, launched in the summer of 1909 by Messrs. Osbourne Graham and Co., Sunderland, to the order of the Ericsson Shipping Company of Newcastle-on-Tyne, is another departure from accepted ideas. She is an ordinary “tramp” steamer so far as dimensions and engine-power go; her only difference, and it is an important one, is that she has two corrugations running along each side between bilge and load water-line, and extending from the turn of the bow to the turn of the quarter. These corrugations do not project very greatly, but according to the inventor, they so affect the stream and wave action around and under the vessel that a source of wasted energy is prevented, and more power becomes available for propulsion. The Monitoria’s dimensions are: length, 288 feet 6 inches over all; breadth, 39 feet 10¹⁄₂ inches; the breadth over the corrugations is nearly 42 feet. The space for bulk cargoes is greater than on her sister ships by the cubic contents of the corrugations, but the tonnages remain unaltered. As a sea-going ship it was found that the corrugations made her much steadier, acting as though they were bilge keels, and that the coal consumption was less, notwithstanding that she made faster time than her sister vessels under precisely similar conditions.
The “Monitoria”: Transverse Section.
The third innovation is the application of the belt-conveyor principle to a collier. The steamer Pallion, in which the machinery is installed, is equipped throughout with twin belt conveyors which, travelling fore and aft the vessel in a space under the cargo, carry the cargo towards the stern, whence it is carried on other belts at the front of the poop for delivery. The latter belts are carried on swivel booms which can be raised or lowered or moved sideways, so that the cargo is delivered direct by the belts into railway trucks on the quay or into barges, and the operation can be conducted at the rate of 250 tons an hour on each side of the vessel simultaneously. Under this system no shoots are used, and there is no handling of the coal. The Pallion requires only about six hours to discharge a full cargo with six men, as against over a hundred men and eleven hours in the ordinary way. Her water-ballast tanks can be emptied or filled as fast as the cargo is placed in her or taken out. She was built by the Doxford firm at Sunderland for a Newcastle Shipping Company.
The carrying of petroleum in bulk has spread enormously of late years in both steamers and sailing vessels specially designed for the purpose. In all such vessels the method of the subdivision of the holds into tanks is of the greatest importance, together with that of ventilation, and every builder and owner of such vessels has his own theories as to the best means to be adopted. A later type of tanker has the engines astern. A further innovation in this class of steamer is to fit them for burning oil fuel, the two big tankers Oberon and Trinculo having had the necessary installation placed in them last year at Smith’s Dock, North Shields, sometimes called “the home of tank-steamer repairing work.”
An economical method of transporting oil in bulk across the Atlantic is adopted in the case of the steamer Iroquois, which herself carries about 10,000 tons of oil in bulk, and also tows with her the sailing barge Navahoe, carrying an equal quantity, one set of engines thus doing duty for both cargoes. The Navahoe is the largest sailing ship in the world, is schooner-rigged on all her six masts, and is able to make her way to port in case she becomes separated from her consort.