The slips of the shipyards at Alt-Hofen (Hungary) belonging to the Imperial and Royal Navigation Company of the Danube are so arranged that the vessels belonging to its fleet can be hauled up high and dry or be launched sidewise. They comprise three distinct groups, which are adapted, according to needs, for the construction or repair of steamers, twenty of which can be put into the yard at a time. The operation, which is facilitated by the current of the Danube, consists in receiving the ships upon frames beneath the water and at the extremity of inclined planes running at right angles with them. After the ship has been made secure by means of wedges, the frame is drawn up by chains that wind round fixed windlasses. These apparatus are established upon a horizontal surface 25.5 feet above low-water mark so as to give the necessary slope, and at which terminate the tracks. They may, moreover, be removed after the ships have been taken off, and be put down again for launching. For 136 feet of their length the lower part of the sliding ways is permanent, and fixed first upon rubble masonry and then upon the earth.
Fig. 1 gives a general view of the arrangement. The eight sliding ways of the central part are usually reserved for the largest vessels. The two extreme ones comprise, one of them 7, and the other 6, tracks only, and are maneuvered by means of the same windlasses as the others. A track, FF, is laid parallel with the river, in order to facilitate, through lorries, the loading and unloading of the traction chains. These latter are ¾ inch in diameter, while those that pass around the hulls are 1 inch.
The motive power is furnished by a 10 H.P. steam engine, which serves at the same time for actuating the machine tools employed in construction or repairs. The shaft is situated at the head of the ways, and sets in motion four double-gear windlasses of the type shown in Fig. 2. The ratio of the wheels is as 9 to 1. The speed at which the ships move forward is from 10 to 13 feet per minute. Traction is effected continuously and without shock. After the cables have been passed around the hull, and fastened, they are attached to four pairs of blocks each comprising three pulleys. The lower one of these is carried by rollers that run over a special track laid for this purpose on the inclined plane.
FIG. 1.--WAYS OF LAUNCHING VESSELS SIDEWISE.
The three successive positions that a boat takes are shown in Fig. 1. In the first it has just passed on to the frame, and is waiting to be hauled up on the ways; in the second it is being hauled up; and in the third the frame has been removed and the boat is shoved up on framework, so that it can be examined and receive whatever repairs may be necessary. This arrangement, which is from plans by Mr. Murray Jackson, suffices to launch 16 or 18 new boats annually, and for the repair of sixty steamers and lighters. These latter are usually 180 feet in length, 24 feet in width, and 8 feet in depth, and their displacement, when empty, is 120 tons. The dimensions of the largest steamers vary between 205 and 244 feet in length, and 25 and 26 feet in width. They are 10 feet in depth, and, when empty, displace from 440 to 460 tons. The Austrian government has two monitors repaired from time to time in the yards of the company. The short and wide forms of these impose a heavier load per running foot upon the ways than ordinary boats do, but nevertheless no difficulty has ever been experienced, either in hauling them out or putting them back into the water.--Le Genie Civil.
FIG. 2.--DETAILS OF WINDLASS.