SLIP, among shipbuilders is used to denote a place with a gradual slope on the banks of a river, suited for shipbuilding.
Mr. Thomas Morton, late shipbuilder, Leith, has given the same name to an apparatus for hauling ves sels out of the water, in order to be repaired. This contrivance is a substitute for dry docks, and having erected it in his own building yard at Leith, and brought it to perfection by successive improvements, Mr. Morton secured the exclusive right to it by a patent.
Mr. Morton's slip is represented in section in Plate DII. Fig. 1, where A, B, C, are the sections of three railways, forming a plane, inclined at nearly the same angle, as the slips generally used by shipbuilders. This railway is placed on a sloping beach, and ex tends from above the reach of the tide down to low water mark. A carriage or frame of timber seen in section at D, E, F, G, H, runs along the iron railway upon rollers on truck wheels, guided by flanges. Blocks are laid upon the middle or keel beam E of the carriage to such a height, that the keel of the vessel may clear the ends of the cross pieces D and F, and each block embraces four trucks, two on each side of the beam. The blocks seen at M and N, which slide upon the cross pieces, are made up to suit the rising of the ship's bottom; they run out to the extremity of the cross pieces, and their ropes r, s, (r belonging to the left hand blocks, and s to the right hand ones) crossing the carriage, are reeved through a sheave attached to the opposite cross piece, up to the top of the rope rod. The shores S, S, (when any are ne cessary) are put into their places, turn upon a joint at T, and are prevented, when the vessel is floating on, from falling outwards by a small chain. Mr. Morton was at first in the practice of using shores; but hav ing never found the slightest inconvenience or risk, even with vessels of the sharpest bottoms, many of which have been upon the slip, he has not of late found it necessary to use them, though they are par ticularly specified in his patent. Ile is still of opin
ion, however, that they may be useful when ships of war are brought upon it, for which, he is confident, it is well calculated.
In order to haul ships ashore, the carriage thus pre pared is let down the-inclined plane generally at low water. The chain of a powerful purchase is then at tached to the carriage, and a waterstaff is placed at the fore end of the keel beam, to mark the depth of the water, and to be a guide in floating the vessel on. The vessel is then brought to the lower end of the carriage, and hauled over it, (having bow and quarter lines to steady her) till the advanced part of the keel takes the blocks between the fore foot guides. The ends of the ropes 7' s are now taken on board from the rods R R, but kept slack, and the vessel is hauled for ward as the water flows, until the keel takes the blocks at the contracted part of the guides, which are just wide enough to receive it. Being still afloat abaft, having been previously so trimmed, the vessel is then adjusted over the blocks abaft by a water line. When the iron guides a b, c d, are hauled up by their ropes a e, d f, they confine her to settle down truly. By heaving the purchase, she will soon take the blocks abaft, which is observed by the water mark left upon her bottom. She is trimmed upright, and the fore most bilge, or sliding blocks, hauled in tight. As she rises out of the water, each succeeding block is hauled in, but not till the weight of the vessel has settled well on her keel; and the shores (if used) are brought to her sides, and there secured. Thus prepared, she is hauled up the inclined plane at the rate of from 21 to 5 feet per minute, by six men to every hundred ton. When hauled up, she is shored from the ground; the keel beam is secured from moving; and the sliding blocks, with the cross pieces arc, in a few minutes, removed, when the vessel is ready to be repaired.