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Plan and Elevation of a 74 Gun Ship&c.

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London Published by Thomas Tepa. 73.Cheapside April 1.2829.

J. Shury se

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of the bottom is determined by the qualities which are necessary for the vessel, and conformable to the service for which she is proposed. The upper works comprehend all that part which is usually above the water when the ship

is laden.

The limits of our design will not admit of a minute description and enumeration of all the pieces of timber which enter into the construction of a ship, nor of a particular description of their assemblage and union; or the manner in which they reciprocally contribute to the solidity of those floating citadels. It nevertheless appears necessary to give a general idea of the use, figure, and station of the principal pieces, to those who are entirely unacquainted with the subject. As our definitions will be greatly illustrated also by the proper figures, we have annexed to this article a plate, which comprehends some of the most material draughts, as well as a representation of the principal pieces employed in naval architecture.

It is usual among shipwrights to delineate three several draughts.

1. The whole length of the ship is represented according to a side view, perpendicular to the keel, and is termed the plane of elevation, or sheer-draught. Plate I. SHIP-BUILDING, fig. 1.

2. The ship is exhibited according to an end view, and stripped of her planks, so as to present the outlines of the principal timbers; and this is properly termed the plane of projection, or the vertical plane of the timbers, because it shows the projection of their frames relatively

to each other.

3. It is not sufficient to have the vertical curves of the bottom in different places; for a distinct idea of the horizontal curves is also equally necessary and useful: this is obtained by means of water-lines traced upon what is called the horizontal plane.

The elevation or sheer draught determines the length and depth of the keel; the length and projection, or rake of the stem and stern-post; the position of the midship-frame upon the keel, together with that of the principal frames afore and abaft; the wales, the dimensions and situations of the gun-ports, the projection of the rails of the head and quarter gallery, with the stations of the masts and channels.

This draught, however, conveys no idea of the vertical curve of the ribs or timbers; for, as their projection will be only represented in a plane elevated upon the length of the keel, they will appear in this direction no otherwise than as straight lines. To perceive these curves accurately, they must be regarded in another point of view, which will represent their projection upon a vertical plane, supposed to cut the keel at right angles in the place where the ship is broadest. For, as all ships are broader near the middle of their length than towards the extremities, it is evident that the timbers are more extended in proportion. The most capacious of these represents what is called the midship-secthe area of this section is deli

tion;

and upon neated the projection of all the others. Thus the plane of projection limits the different breadths of a ship in various points of her

length, and exhibits the outline of the timbers respectively to each other, as they are erected upon the keel. Accordingly, this draught ought to present a variety of sections of the ship in different places of her length, and always perpendicular to the upper edge of the rabbet of the keel, so that the eye of the observer, when placed in what may be properly termed the axis of the ship, may perceive the several sections at one glance; that is to say, when looking full on the stem, from before the ship, discover the fore timbers; and, when looking from behind, directly on the stern, he shall perceive the form of the after timbers.

To form a just idea of this plane, therefore, we ought to suppose a ship resting upon the stocks, in the same position as when afloat upon the water. Thus a variety of black vertical lines may be drawn at equal distances upon the bottom, which is white, to form different outlines of the ship corresponding to the timbers within. It is to be observed that the fashion of the inferior timbers must conform to the figure of the midship-section, which is placed in the fullest part of the ship; and, as the planes of all the other timbers diminish in a certain progression as they approach the stem and stern, they are properly delineated on the plane of the midshipsection, which also represents the depth of the keel and length of the midship-beam.

As the two sides of a ship ought to be exactly alike, it is judged sufficient to represent the sections of the fore part of the ship on the right side, and those in the after part on the left, so as to perceive all the sections, as well afore as abaft, upon one plane. See PROJECTION, plate I. SHIP-BUILDING, fig. 2, 3.

However necessary it may be to understand precisely the vertical curves of the bottom, it is no less requisite to have a just idea of those which are horizontal.

The horizontal, or floor plane, is that upon which the whole frame is erected, and will be more clearly understood by previously describing the water-lines and ribands of which it is composed.

When a ship floats upon the stream, it is evident that her upper works will appear to be separated from the bottom by the surface of the water, which will accordingly describe an imaginary horizontal line upon the bottom from the stem to the stern-post.

The most elevated of those lines is termed the upper horizontal or water-line; and, in order to prove the fairness of the body, the several horizontal lines are set up at equal distances above the base line, and distinguished by the water lines H, I, J, K, L, in the projection. This we would always recommend to be done, although the water lines of many ships are not parallel with the line of the keel; for, unless they are parallel with the keel, they cannot answer the intended purpose of laying off the ship.

By lightening a ship gradually, and at the same time preserving the direction of her keel, or the angle which it makes with the surface o. the water, a variety of water lines may be drawn parallel to each other.

The ribands are likewise of great utility in

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SHIP-BUILDING.

narrow and flexible ship-building; they are planks placed on the bottom at different heights, so as to form a sort of mould for stationing the inferior timbers between the principal ones. They differ from the water-lines, inasmuch as the latter have only one curve, which is horizontal, whereas the ribands, besides their horizontal one, have vertical curves from the main-breadth upwards.

We have already observed that the qualities required in a ship ought to determine the figure of the bottom: a ship of war, therefore, should be able to sail swiftly, and carry her lower tier A mer of guns sufficiently out of the water. chant ship ought to contain a large cargo of mercantile goods, and be navigated with few hands; and both should be able to carry sail firmly, steer well, drive little to leeward, and sustain the shocks of the sea without being violently strained.

The first thing to be established in the draught of a ship is her length; and, as a ship of war, according to her rate, is furnished with a certain number of cannon, which are placed in battery on her decks, it is necessary that a sufficient distance should be left between the ports to work the guns with facility, and particularly to leave space enough between the foremost gun and the stem, and between the aftmost gun and the stern-post on each side, on account of the arching, or inward curve of the ship towards her extremities.

When the length of a ship is determined, it is usual to fix her breadth by the dimensions of the midship-beam. On this occasion the shipwrights, for the most part, are conducted by rules founded on their own observation; for, having remarked that some vessels, which by repeated experience have been found to answer all the purposes of would navigation, have a certain breadth in proportion to their length, they have inferred that be improper to depart from this proportion: but, as other ships have been constructed with different breadths, which were equally perfect, a variety of different general rules have been adopted by these artists, who are accordingly divided in their opinions about the breadth which ought to be assigned to a ship relatively with her length, whilst each one produces reasons and experience in support of his own standard. Those who would diminish the breadth allege, 1st. That a narrow vessel meets with less resistance in passing through the water; 2dly, That by increasing the length she will drive less to leeward; 3dly, That, according to this principle, the water-lines will be more conveniently formed to divide the fluid; 4thly, That a long and narrow ship will require less sail to advance swiftly; that her masts will be lower, and her rigging lighter; and, by consequence, the seamen less fatigued with managing the sails, &c. Those, on the contrary, who would enlarge the breadth, pretend, 1st, That this form is better fitted to receive a good battery of guns; 2dly, That there will be more room to work the guns conveniently; 3dly, That, by carrying more sail, the ship will be enabled to run faster; or, that this quality will at least overbalance the advantage which the others have of more easily divid

ing the flood; 4thly, That being broader at the
load-water line, or place where the surface of the
will admit of being very narrow on the floor
water describes a line round the bottom, they
particularly towards the extremities; and, 5thly
That a broad vessel will more readily rise upon
the waves than a narrow one.

From such opposite principles has resulted
that variety of standards adopted by different
shipwrights; and a servile imitation of these me-
chanical methods has, to the great reproach of
the art, produced all these pretended rules of
proportion; for the various models they have
hitherto adopted indisputably prove their doubt
Hence these pretended mysteries
and uncertainty with regard to their proper
standard.
which are only to be revealed to such as are ini-
tiated into the craft! And hence violence of
artists! Indeed, nothing appears more effec-
opposition and mutual contempt amongst the
tually to have retarded the progress of naval
architecture than the involving it in mysteries
which the professors would gravely insinuate are
only intelligible to themselves. This ridiculous
affectation is, nevertheless, too generally retained,
notwithstanding the example to the contrary of
some of the most able shipwrights in Europe,
who are real masters of the theory of their art,
and do honor to their profession, and who are
justly exempted from the censure to which the
others are often exposed.

It is not to be expected that an art so compli-
cated and various, comprehending such a diver-
sity of structures, can be treated at large in a
work of this sort. To enter into a particular
detail of the theory and practice, to explain the
different parts with sufficient accuracy and perspi-
cuity, would of itself require a large volume, and,
consequently, much exceed the limits of our de-
description into a narrow compass, it will be
sign. Being thus necessitated to contract our
sufficient to give a general idea of the subject, to
describe the principal pieces of which a ship is
composed, and to explain the principal draughts
used in the construction thereof.

As the several lines exhibited in the planes of elevation, projection, &c., will be rendered more intelligible by a previous account of the principal of those pieces, it may be proper to begin with reciting their names, and giving a summary description of their uses and stations. They are, for the most part, represented according to the order of their disposition, in fig. 4, and termed pieces of the hull.

A, the pieces which compose the keel, and B, the stern-post, which is tenoned into the which are securely bolted together, and clenched. C, the stem, which is composed of three pieces, keel, and which unites the sides of the ship abaft. scarfed together, into which the ship's sides are united forwards.

let.

D, the inner post, into which the transoms are

E, the false post, which serves to augment the
F, the pieces of dead-wood, which form the
breadth of the stern-post.
after-part of the ship.

G, the knee of the stern-post, which unites it
to the keel.

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O, the foremost fashion-piece on one side; the heel of which is connected with the dead-wood, and the head is secured to the wing-transom P, the middle fashion-piece.

Q, the after fashion-piece.

keel, by which we shall be enabled to judge of the rake of the stem and stern-post. The rake is known to be the projection of the ship at the height of the stem and stern-post, beyond the ends of the keel afore and abaft; or the angle by which the length is increased as the fabric rises. To these we may also add the height of the stem and wing-transom.

As a ship is much broader at the middle than at the extremities, the arms of the floor-timber will form a very obtuse angle at the extreme breadth; but this angle decreases in proportion to the distance of the timbers from the midshipsection, so that the foremost and aftmost ones will form a very acute angle.

Shipwrights differ extremely in determining the station of the midship-section; some placing it at the middle of the ship's length, and others

R, the side counter-timber, which steps on the farther forward. They who place it before the end of the wing-transom.

S, the sternson.

T, the gripe.

U, the lengthening piece on the side countertimber.

V, the scarf of the after-piece of the keel. W, the pieces which compose the kelson, and which are scarfed together, and placed over the middle of the floor timbers, upon each of which they are scored about an inch.

Y, the several pieces of the knee of the head; the lower part of which is fayed to the stem; the heel being scarfed to the gripe.

In vessels of war the general dimensions are established by authority of officers appointed by the government to superintend the building of ships. In the merchant-service the extreme breadth, length of the keel, depth of the hold, height between decks and in the waist, are agreed on by contract; and from these dimensions the shipwright is to form a draught suitable to the trade for which the ship is designed.

In projecting the draught of a vessel of war, the first article to be considered is her length. As every ship is much longer above than below, it is also necessary to distinguish the precise part of her height, from which her length is taken this is usually the lower gun-deck, or the load-water-line. It has been already observed that water-lines are described longitudinally on a ship's bottom by the surface of the water in which she floats, and that the line which determines her depth under the water is usually termed the load-water-line. In this draught it will be particularly necessary to leave sufficient distance between the ports.

The next object is to establish the breadth by the midship-beam. Although there is great difference of opinion about proportioning the breadth to the length, yet it is most usual to conform to the dimensions of ships of the same rate. After the dimensions of the breadth and length are determined, the depth of the hold must be fixed, which is generally half the breadth: but the form of the body should be considered on this occasion; for a flat floor will require less depth in the hold than a sharp one. The distance between the decks must also be settled.

He may then proceed to fix the length of the

middle, allege that, if a ship is full forward, she will meet with no resistance after she has opened a column of water; and that the water so displaced will easily unite abaft, and by that means force the ship forward; besides, having more power on the rudder, in proportion to its distance from the centre of gravity; this also comes nearer the form of fishes, which should seem the most advantageous for dividing the fluid. When the rising of the midship-floor-timber is decided, we may then proceed to describe the rising-line of the floor, on the stern-post abaft, and on the stem afore.

The height of the lower-deck is the next thing to be considered. It is determined in the middle by the depth of the hold; and some builders make it no higher than the stem; but they raise it abaft as much above its height in the middle as the load-water-mark, or draught of water abaft, exceeds that afore. With regard to the height between decks, it is altogether arbitrary, and must be determined by the rate of the ship, and the service she is designed for. It is also necessary to remember the sheer of the wales, and to give them a proper hanging; because the beauty and stateliness of a ship greatly depend upon their figure and curve, which, if properly drawn, will make her appear airy and graceful on the water.

We come now to consider the upper-works, and all that is above water, called the deadwork and here the ship must be narrower, so that all the weight lying above the load-waterline may thereby be brought nearer the middle of the breadth, when of course the ship will be less strained by the working of her guns, &c. But, although some advantages are acquired by diminishing the breadth above water, we must be careful not to narrow her too much; as there must be sufficient room left on the upper-deck for the guns to recoil. The security of the masts should likewise be remembered, which requires sufficient breadth to spread the shrouds. A deficiency of this sort may indeed be in some measure supplied by enlarging the breadth of the channels.

We shall now proceed to explain the plane of elevation or sheer-draft of a modern seventyfour gun ship as represented in Plate I. fig. 1.

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