SHIPS.
BUILDING SLIPS.
FIG. 1.
FIG. 2.
The first part of a ship “laid down” is the “keel;” this is the projection which runs along the whole length and forms the lowest part of the ship. The ship is built in what is called the “building slip,” which slopes towards the water; in this “slip” a row of oaken blocks are placed at a few feet apart, and about three feet high, on which the keel is laid; these blocks are for the purpose of allowing the workmen to cross from side to side below the keel and to form a foundation for the ship to rest on. In [fig. 1], A is this arrangement of blocks, C the keel, at the hinder part of which is the “dead wood,” or the timbers filling up the space between the keel and the curved bottom of the ship, which is more curved than the keel, and very much so towards the “stern” or hindermost part. Across the keel are laid the “floor-timbers” or “ribs,” B, which are curved timbers laid at right angles to the keel and passing outwards and upwards in the exact curve which the sides of the ship are to assume; these are too curved and too long to be of one piece, others, therefore, are added, and joined end to end with the first by wooden bolts or “dowels;” these curved timbers are cut to a pattern, chalked on the floor of the “mould-loft.” The ribs as they cross the keel are bound to it by a piece of strong timber running along inside of or above them, but parallel to, and exactly over it, which is called the “keelson,” and is bolted to the keel through the centre of each lower piece of the ribs or floor-timbers; it is shown at D, [fig. 1]. In large ships there are three of these keelsons, running side by side, and forming a strong support to the masts, which rest upon them. At each end of the keel a bar of timber rises, the hindermost being called the “stern-post,” and that in front the “stem-post” (marked E and F in [fig. 1]). Across the ribs on the outside and parallel to the keel, are laid the “planks,” which are boards of oak of from two to six inches thick, laid close together and touching at their edges; these are fastened to the ribs by plugs of oak, called “treenails,” going right through the planks and ribs, and wedged at each end ([fig. 2]). In large ships, similar planks line the inner side of the ribs, and oblique or diagonal braces are also sometimes used, to strengthen the ship and keep it from curving or “arching” when in the water.
FIG. 3.
MAST HOUSE.
The masts of a “ship” are three in number, a “schooner” has two, and a “sloop” but one. These masts pass right down through the decks, and rest upon the keelson. In small vessels each division is made of one piece, but in larger ships they are made up of a central piece, with others fastened round it so as to enlarge and strengthen it. The first or lower division of the central mast is called the “main” mast, and that above it the “maintop” mast; the fore mast is divided into “fore” mast and “foretop” mast, and the after mast is called the “mizen” and “mizentop” mast, and the pieces above these the “foretop gallant” mast, “maintop gallant” mast, and “mizentop gallant” mast. These masts are made, and raised by cranes in a building called a mast-house, and placed in the right position in the ship floating beneath.
The outside of ships, as high as the “water-line,” is covered with a sheathing of copper to defend it from the action of the “worm” (Teredo navalis), which bores into and destroys the wood exposed to its ravages; the copper also presents a smooth surface to the water, and facilitates the motion of the vessel. At the stern of the ship is placed the “rudder,” a wooden construction turning like a door on fastenings, and which, by being moved on one side, presents a greater amount of resistance to the water, and consequently tends to turn the stern of the ship away from that side, thus altering its course. The decks of a ship are like the floors of a house, running across from side to side, and supported on strong beams bolted into the sides; they are slightly arched, to increase their strength, as they have in ships of war to support the weight of the guns, &c. A section of the decks and other parts of a ship is shown at [fig. 3]. where the general figure and the different parts described may be seen; the section is through the middle, from side to side. Most ships of any considerable size carry several boats with them, either on deck or suspended between the masts, to serve as a means of escape in case of fire, or any other accident requiring the crew to leave the ship, also as a means of keeping up communication with the shore. Ships of war are named according to the number of guns they carry, as a seventy-four, a hundred-and-twenty-gun ship, &c.
REPAIRING DOCK.
When ships have to be repaired they are brought into the repairing dock, which has a pair of gates shutting it off from the river; when they are closed (at low water) the water is pumped out from the dock, and the repairs done; when finished the water is let in, and the ship floats out. In small vessels it is sometimes sufficient to haul them on shore at high tide, so that when the tide is down they may be left high and dry and repaired, and when the tide is at the highest, hauled off again. Steam ships are constructed to be propelled either by paddle wheels having flat boards fixed to their circumferences, which on being turned round, take a great hold in the water, and so cause the motion of the ship; or by the screw-propeller, which has been described.
PADDLE AND SAILING SHIP.
BREAKING UP.
The iron ships, which of late have almost superseded those of wood, are made of plates of wrought iron, rolled, while red hot, between rollers to the thickness required, which is generally half-an-inch; these plates have holes punched all round them by machinery, and are united by rivets placed in the holes red-hot and rivetted by heavy hammers. The most magnificent specimen of iron shipbuilding ever attempted is the Leviathan. This ship is 680 feet long, and is not made of one thickness or case of iron plates, but is upon a new principle called the “cellular,” consisting of an outer and inner casing of iron plates held together by partitions of iron so as to separate them into square compartments or “cells.” The objects gained by this arrangement are greater strength, and greater safety, for in case of injury to the outer portion, the water would enter only between the two in that compartment where the injury happened to be, and so fill only that small portion with water. The whole ship is also divided into compartments by means of double screens of iron, making it like a fire-proof box, and even if a fire should occur in one of these, the others would be preserved from its effects. The masts and yards of this great ship are also of hollow wrought iron plates rivetted together, and are both stronger and lighter than they would be of wood. A machine is placed at the lower part of each mast which by compressing, can crush it up, and cause it to break off and fall over the side of the vessel in case such a thing should be required, as in a very violent storm; and the standing rigging, which is of wire-rope, can be let loose in a few minutes so as to completely free the ship of the mast. This great ship is constructed to be propelled both by screw and paddles; the screw engines are four in number, and are each of 1,600 horse power, the paddle engines are also four, of 1000 horse power each, being 10,800 altogether. They will require about 180 tons of coal a day to work them; 12,000 tons of which are capable of being carried. The Leviathan will have six masts, and be able to spread 6,500 yards of sail, will accommodate 4000 passengers, and when ready to sail, with all on board, will weigh about 25,000 tons.