The Mechanical Handling and Storing of Material

COALING VESSELS AT SEA 33* the speed of the upper strand. On the other hand, if the ships reduce the distance between points of support, the speed of the upper strand is reduced. When the carriage reaches the pulley at the shear-head, it collides with it—at reduced speed—and thus striking, releases the lower hook, and the two bags and their bail drop into the canvas shoot and slide to the deck of the warship. Loads drop in this manner at the rate of one per minute. The empty carriage is drawn back by the rear drum, the forward drum being thrown partially out of friction. An auxiliary f-in. rope, known as the sea-anchor line, is stretched above the two strands of the conveyor line, and under a pulley on the carriage. This rope is attached by a “knock-off hook” to the superstructure of the vessel, and rests in a “saddle” on the shear-head, whence it leads through the carriage over pulleys at the head of the foremast and mainmast of the collier, and runs on astern several hundred feet into the sea. To the end of this rope a drag or sea anchor is attached, made of canvas in the form of a cone. This sea anchor is selected in reference to the speed at which the ships are to travel. In a smooth-water test, speeding at 6 knots, a drag 7 ft. in diameter at the base was used. During the rough-weather trial, the same anchor seemed to give the required tension at 5 knots. The sea-anchor line is to support the carriage, when empty, on its return to the collier. It permits the conveyor line to be slack, and prevents the overturning or twisting of the carriage. Doubtless at times it helps also to support the load in transit across, but instantaneous photographs taken during the transit of the load show the sea- anchor line slack, thus demonstrating that the tension device on the conveyor line is sufficient to keep the load above the water during transit. The tests which were made by a Board of United States Naval Officers showed that from 20 to 25 tons of coal per hour could be delivered from the collier to the vessel even when a moderate gale was blowing. The towing vessel, which in this instance was a United States battleship, consumed from 3 to 4 tons of coal per hour. Consequently the amount actually received into the bunkers ranged from 16 to 20 tons, which would be an average of 375 tons in twenty-four hours. It is claimed that such a low speed would not be necessary in regular service, and that the vessels might proceed at a speed of from 8 to 10 knots an hour if desired. However, the consumption of coal on the towing vessel would be largely increased unless the collier could proceed under her own steam. There is a danger, however, that the proper distance to be maintained might then be lessened, whereupon the cable would sag, and thus cause a cessation of operations. While one of the principal advantages claimed for the system is that a battleship or merchant liner can take coal on a voyage without the necessity of entering the harbour, thus saving time, the process of transferring fuel can also be thus carried out with a minimum of hand labour. One man is required at the hoisting engine, which is very similar to the steam winch now used for transferring cargo on board the large merchant steamships. A squad of twenty men is required in the hold of the collier to fill the bags and deliver them to the deck, while another squad of from fifteen to twenty transfer the bags to the lift. But one man is ordinarily required to do the overhead work, and he is stationed in the trestle-trees of the collier ; but for greater safety, two men are employed when the weather is rough and the ship is pitching heavily. The only hands who are required on the receiving ship are stationed at the top of the platform or shear-head to empty the bags into a canvas shoot and return them. There is, of course, a force of bunker trimmers in the hold. In coaling the battleship, it .was found that the loads