BUNKERING ON THE OPEN SEA This was formerly much practised by the navies of different nations, but has now been almost entirely superseded by oil-fuel bunkering in port. The method is very complex, and it is not necessary to describe it in detail here : it is similar to that em ployed in rope and cableways. One terminal trestle is on the collier and the other on the ship to be bunkered. One vessel tows the other, keeping taut the connecting cable, which is well above the water; the coal in sacks is transferred along the cable by an endless hauling rope.
For oil-fuel bunkering at sea while under way, cable com munication is similarly established between the vessels, but on a lower level. A hose-pipe is festooned on the cable so that the oil fuel can be pumped from one vessel direct to the bunkers of the other.
Since the capacity of these me chanical bunkering devices has frequently to be curtailed because the rate of trimming to the bunkers cannot keep pace with the rate of delivery, mechanical trimming devices are often employed. One method has already been alluded to in the description of the "De Mayo" plant, but a more efficient system, used particularly for loading coal on to big liners, is the "Lane-Galloway" trimming machine. This was originally installed at Curtis Bay (Md.) , U.S.A., where large quantities of coal are loaded into vessels. The principle embo,iied is that of an endless band conveyor, some times fitted with cross cleats, on to which the coal is delivered. The speed of this band-2,7ooft. per minute—is such as to im part to the coal when leaving the belt a velocity sufficient to throw it right across the bunker. The length of the belt is 3ft. to Oft. from centre to centre and the width 48in. A machine on a similar principle is used in Scotland, the action of which is shown in fig. 7.
