All About Engines

Engines for Ships 305 the best method of ship propulsion, which will quickly overhaul its competitors. . The third method is to use steam turbines to drive dynamos and to use the electricity thus pro- duced to drive motors coupled to the propeller shaft. The rapidity with which an electric current can be switched on or off, and the ease with which it can be regulated are much in favour of this plan, but the electrical machinery adds greatly to the weight. It was strongly advocated by the late Mr. H. A. Mavor, of Glasgow, and has been tried on several ships , but there are no signs yet of its becoming popular. In any case it is less efficient than the geared turbine, and there is an increased number of appliances in which a breakdown may occur. The fourth and last method was proposed by a German named Fottinger, and was tried in 1913 with a vessel of 10,000 horse-power. In this case a turbine drives a centrifugal pump, and the water from the pump drives a water turbine on the pro- peller shaft. The idea is very simple, and the same water circulates round and round through the pump and turbine. But both in this and the preceding method 15 per cent, of the power is lost in the extra machinery, and at present neither of them is a serious rival to the geared turbine. The machinery of a modern ship is not confined to the main engine room, but to deal with all the engines, winches, pumps, and so on would take up more space than can be afforded here. For example, u