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Athwart a keel of large squared timbers, scarphed together and forming with a massive inner keelson the principal member or backbone, were laid the curved frames or ribs which, bolted to each other and to the keel with iron bolts washered and clinched, gave to the hull its transverse strength and form. These frames were held together, as they curved upward from the ground or floor level, by thick longitudinal wales, worked externally along the frames at convenient heights, and curved so as to suit the degree of sheer desired.
At the fore end the wales and frames converged to the centre-line and the keel was prolonged upward to meet them in a curve or compassing timber, forming the bow or stem: to the beauty and shapeliness of which, with its projecting beak-head, the builder devoted much of his attention and skill. At the other end the frames and wales converged to a square and lofty stern. The stern post was a massive timber fastened to the keel and sloping somewhat aft from the vertical, and from it rose two fashion-pieces “like a pair of great horns,” which formed, with the horizontal arch and transom timbers, the framework of the stern. When the frames had been built up to the requisite height the upper ends of each opposite pair were joined across by horizontal beams, which were secured to them by means of brackets or knees; such beams were worked at the level of the main and other decks, and served to support them when laid. Joined by its beams, each pair of frames thus formed a closed structure: a combination of members which was to resist crushing and deformation, the blows of the sea, the stresses of gunfire, the forces due to the weight of the guns and the vessel itself, and especially the forces thrown on it when the vessel was aground or on a careen. The rigidity of this combination was enhanced by the fitting of pillars which were placed vertically over the keelson to support each beam at its middle. And sometimes the lower pillars were supplemented by sloping struts, worked from the curve of the frames up to the middle of each beam above.
The skeleton of a ship thus formed, built with well-seasoned timber, was left standing on the stocks “in frame” for a considerable period, sometimes for years, exposed to the open weather. On it eventually a skin of planks was fastened, secured by wood trenails split and expanded by soft-wood wedges, both internally and externally; and inside the ship, to reinforce the frames and in line with them, timbers known as “riders” were worked. On the beams the decks were laid: the orlop below the water-line level, and above it, at a height suitable for the ordnance, the main or gun deck; above that the upper deck, on the ends of which were reared the poop (sometimes a half-deck, extending from the stern to the mainmast, sometimes on that a quarter-deck, over the steerage) and the forecastle.
Such, very briefly, was the mode of ship construction. The resulting structure, when caulked and swelled by sea-water, presented a water-tight and serviceable vessel. Timber provided, for ships up to a certain size, a suitable material. It afforded strength and buoyancy, and elasticity sufficient to obviate local strains and to spread the stresses due to lading, grounding, careening, or the actions of the wind and sea. The different parts of the ship’s frame gave mutual support, and the pressure of the fluid on the exterior of the hull tended, by constraining the component parts, to preserve the vessel.[8]
But the timber-built ship possessed an inherent weakness. Metal plates or girders can be bolted or riveted together so efficiently as to leave the joints between them almost as strong as the sections of the plates or girders themselves. Not so wood beams. However skilfully they might be joined, their joints were necessarily weaker than all other sections: “it was then, and still is, impracticable to develop the full strength in end connections between wooden members.”[9] The softness of the wood was an additional source of weakness. Two beams fastened together by iron bolts might form initially a close and rigid joint; but if, under the action of alternating or racking stresses, they became loosened even in a minute degree, the tendency to become still looser increased: the wood gradually yielded under the bolt washers, the bolts no longer held rigidly, “the very fact that wood and iron were dissimilar materials tended to hasten the disintegration of the structure.” With planking a similar effect obtained. Trenails, expanded by wedges and planed off flush with the planks which they held together, had only shearing strength; if once they were loosened they had little power to prevent the planks from opening further. These weaknesses were recognised. To minimize their effects the butts of frames, decks, and side planking, were arranged so that no two neighbouring butts lay in the same line. But in spite of the most painstaking craftsmanship, the size of the wooden ship was limited by its inability to withstand a high degree of stress. As sizes increased extraordinary endeavours were made to meet the hogging and sagging strains, to prevent cambering of the hull, and to stiffen it longitudinally and circumferentially. Enormous masses of timber were worked into the internal structure in the form of riders, pillars, standards, and shores, “the whole of which had an appearance of great strength, but which in fact, from its weight and injudicious combinations, was useless, if not injurious.”[10] Which did, in fact, clog the ship and usurp the space required for stowage.
As for the masts, experience fixed their number, size and position. In the earlier ships, as we have seen, four and sometimes five masts were fitted, after the Mediterranean style. But later this number was reduced to three. Of these the foremast was the most important, and it was stepped directly over the fore-foot of the vessel, the main and mizzen being pitched to suit. Their height varied with the service and type of ship. Taunt masts, like those carried by the Flemish ships, were best for sailing on a wind, for with them narrow sails could be used which could be set at a sharp angle with the keel; but short masts and broad yards were favoured by English mariners, as bringing less strain on a vessel’s sides and rigging and as being less likely to produce a state of dangerous instability. The masts were short, very thick, and heavily shrouded; the standing rigging was led to channels and deadeyes on the outside of the bulwarks. The bowsprits were large and “steved” upward at a large angle with the horizontal; spritsails and spritsail topsails were set on them, of use mainly when sailing before a wind, yet retaining their place in our navy till, half-way through the eighteenth century, the introduction of the fore-and-aft jib brought about an improvement and in so doing affected the whole disposition of mastage.
One feature of the masting of the old ships is notable: the manner in which the various masts were raked. In the Sea-Man’s Dictionary[11] the trim of a ship was defined as, “the condition, as to draught, staying of masts, slackness of shrouds, etc., in which a ship goes best.” For a given set of conditions there was a certain rake of masts, a certain position of the centre of wind-pressure against the sails, which, when discovered, gave to the vessel its finest sailing qualities. The knowledge of this adjustment constituted no small part of the great art of seamanship. In the king’s ships a high proficiency was attained in it; merchantmen sailed under more diverse conditions and showed, it appears, a lower level of scientific inquiry. “Next to men of war (whose daily practice it is) the Scotch men are the best in the world to find out the trym of a ship, for they will never be quiet, but try her all ways, and if there be any goodness in her, they can make her go.” Generally, the effect of raking the masts aft was to make the vessel fly up into the wind, and vice versa; in ships with high-built sterns, especially, it was necessary to have the head-sails set well forward, to keep them out of the wind. To allow the masts to be raked as desired their heels were pared away, and wedges of suitable thickness were driven between them and the “partners.”
Many other factors contributed to affect, in a manner always subtle and frequently inexplicable, the sailing qualities of a ship. The form of the body, the position of masts and the setting up of the rigging, the disposition of weights, the angle of the yards, the conditions of stability, all had their effect on the vessel’s motion, and therefore on her speed through the water. Free water in a ship’s bilge, for example, had an effect on her degree of stiffness, and from this cause her speed was not easily predictable. Charnock relates how, in the colonial wars of the late eighteenth century, an American vessel, the Hancock, was captured after an unprecedented chase, solely because her commander, injudiciously supposing that by lightening his ship he would enhance her swiftness, pumped water out of her. It was noticed, again, that in certain circumstances the speed of a ship increased when the crew turned into their hammocks.
The lines of the ship were drawn without reference to any science of naval architecture, and merely by instinct and the accumulated experience of the builder; the laws of stability and of fluid resistance were at this time unknown. Experience indicated the desirability of a short keel, to make the ship turn quickly; of an ample rake forward from keel to beak-head—“more than a third the length of the keel, commonly,” says Sir Henry Manwayring, for, “a great rake forward gives a ship good way and makes her keep a good wind, but if she have not a full bow it will make her pitch mightily into a head sea.... The longer a ship’s rake is, the fuller must be the bow”; of a fine run aft, so as to let the water flow strongly and swiftly to the rudder and make the ship steer and sail well; of a narrow rudder, so as not to hold much dead water when the helm was over,—yet, “if a ship have a fat quarter, she will require a broad rudder.” The correct formation of the bow was recognised as of the greatest importance, and the most difficult compromise in the design of a ship. A bow too bluff offered much resistance to motion through the water; on the other hand, too sharp a bow lacked buoyancy, and, from the great weight of mastage, headsails, anchors, etc., which it had to support, caused a vessel to pitch badly in a head sea. “If the bow be too broad,” wrote Captain John Smith, in his Sea Man’s Grammar, “she will seldom carry a bone in her mouth, or cut a feather, that is, to make a foam before her: where a well-bowed ship so swiftly presseth the water as that it foameth, and in the dark night sparkleth like fire.”