half-breadth plan, Plate I. thus: first, draw in the collar beams or carlings at the height of the beak-head, to its siding abaft the fore part of the beak-head, upon which draw in the stantions; observing to keep the two outer stantions to the size of the round-houses, and so that they may be kept far enough out for the funnel to come clear of the side. The third stantion from the middle line must be spaced so as to make the bow-chase port. The next stantion within makes the head door; and, the stantion next the middle line is made by the large stantion into which the collar carling is tenoned. On the midship side of the head door is a scuttle over which a flap is hung. The fore tack leads on board through this scuttle to the capstan, occasionally.

The partners of the foremast may next be drawn in the same manner as the main part runs on the gun deck.

The fore hatch and ladderway, as likewise the partners or steps of the capstans, may be represented; also the ladderway and main hatch, the main mast partners, and after hatchway, as directed in the table of dimensions, likewise the partners of the mizen mast.

Upon the plan of this deck the flat is shifted, having strict regard to the lengths. The flat of the deck, close to the side, in ships of war, is oak, which is shifted in suitable lengths from twenty to four and twenty feet, and anchor stocked, or else top and butt, to assist the conversion of the top end. Between the riders the waterways and first strake are consequently cut off, and abaft the riders are two iron standards.

From the deck transom to the aft part of the forecastle, excepting next the side, this deck is laid with deal; and much waste would be made if the butts were not correctly shifted to their lengths, which will be from thirty-six feet to forty feet.

The butts of the binding strakes are to be so disposed as to give as much shift as possible to the hatchways. The binding strakes may be of Eastcountry plank, as English plank can hardly be procured of the lengths required.

Upon this plan is to be drawn the plan of the breast rail and foot rail, with their stantions.

On each side of the main mast, is framed a flat scuttle through which the pumps, &c. may be lifted; and, abaft the mast, is drawn the bracebitts. Abaft the brace bitts, on each side, is a scuttle made use for leading the main top-tackles to an eye-bolt in the upper deck.

The framing of the gratings and ladderway may next be drawn, as directed in the table of dimensions; and, abaft these, the bulk-head of the captain's cabin.

There will be no occasion for a drawing or plan of the round-house; as, besides its beams, there are only the mizen-top-sail sheet bitts, a companion over the captain's cabin, and the steering wheel, if the rudder head is chosen to run so high.

1

GENERAL EXPLANATION

OF THE

METHODS OF LAYING-OFF, OR OF TRANSFERRING THE LINES OF THE SHEER-DRAUGHT AND OTHER PLANS, TO THEIR TRUE DIMENSIONS ON THE MOULD-LOFTFLOOR, PREPARATORY TO THE ACTUAL BUILDING.

We have already shewn, in a full and copious manner, the methods of delineating the Sheer Draught and other plans of a ship. Now, as laying-off in the mould-loft is, in fact, a delineation or expansion of the same plans upon an enlarged scale, the principles of each are similar; yet it is to be observed, that the present subject will not admit of a clear explanation, without the aid of a set of plates upon a scale too large and expensive to be admitted into this work. We are therefore, in this case, under the necessity of referring the reader to the " Elements and Practice of Naval Architecture," noticed at the conclusion of this volume, in which this subject, with all its ramifications, will be found most clearly and fully explained.

From a draught designed upon paper, for the purpose of laying it down, and expanding it to its full size, on the Mould-loft Floor, we must, in the first instance, take off all the dimensions for laying off the body: and, in the manner that we have shewn, with respect to the dimensions of bodies in the construction of the draught, take off what scantlings may be wanted, which will be found in the table of dimensions. These are to be entered in a small book; for, were the draught used upon the floor, it would disfigure it very much.

It may, perhaps, be necessary here to premise a few observations relative to the transferring of lines from one plan to another. The three principal plans are denominated sheer-plan, half-breadth plan, and bodyplan. In order to facilitate the laying off, and to prove the fairness or correctness of the various curves, certain operations are performed, in which the lines peculiar to one plan are transferred to, or shewn upon, another plan. Thus the lines on the body-plan are transferred occasionally, some to the sheer-plan, and some to the half-breadth plan; those of the sheer and half-breadth plan are, in like manner, sometimes transferred to the body-plan: but there is very seldom any occasion to transfer the lines of the sheer-plan to the half-breadth plan, nor those of the latter to the former. The sheer-plan is intended to exhibit heights and lengths on a perpendicular plane or longitudinal section. The half-breadth plan exhibits half the breadth of those heights and lengths on a horizontal

plane; and the body-plan is compounded of heights, breadths, and lengths, on a perpendicular or transverse plane. The lines of the sheerplan are transferred to the body-plan by means of their heights taken at various parts on the sheer-plan, and those same heights, measured off as heights upon the body-plan from the base line. If those heights are set off successively along the base line in the body-plan, they form curves, as, the main-breadth and top-timber line; or diagonals, as the ribband lines; if they are set off above the base line, in succession, on the same vertical, they ascertain the places of other lines on that vertical, as the buttocklines ascertain the places of the timbers. All horizontal lines on the sheerplan will be horizontal on the body-plan, as the water lines when parallel to the keel.

The lines of the half-breadth plan are transferred to the body-plan by means of their distances taken at various parts from the middle line on the half-breadth plan, and those same distances measured off from the middle line of the body-plan, either in a horizontal or diagonal direction. If measured off successively along the middle line, they form curves as the boundary of the floor sweeps. If measured diagonally, they ascertain the places of other lines on that diagonal, as the timbers are by the diagonals. All lines parallel with the middle line on the half-breadth plan are equally parallel with, and equidistant from, the middle line of the body-plan as the buttock-lines.

Mould-lofts are seldom long enough to admit the laying off of any large vessel in one length; in small mould-lofts they must, of course, lay off in three or four lengths. To lay off in one length would also cause unnecessary waste of time, for many of the perpendiculars of the forebody answer alike for the after-body also.

The Mould-loft Floor being cleared, we begin by striking a straight line from one end to the other, in distance from the side of the loft about as much as the keel is deep, if it will admit of it.

This line will represent the upper edge of the rabbet of the keel, in the sheer and body plans, above which all heights are to be set up; and, it will represent, also, the middle line of the half-breadth plan.

Now, upon this line set off and erect towards the right hand, the foremost perpendicular; from the foremost perpendicular set off the station of dead-flat, and two or three timbers abaft it. Then strike in the intermediate perpendiculars representing the joints of the frame timbers taking their Room and Space from the draught or table of bodies.

Having erected the perpendiculars, or joints of the frame timbers, the stem may be represented in the sheer-plan, and the square bodies laid off according to the method before described, for drawing the sheer draught: nothing more being requisite, than to enlarge them to their full size on the floor.

The moulds for the timbers of the square body being made, the bevellings may be taken, as till then the timbers which have bevellings cannot be cut out. It is a custom with some to have only two bevelling boards, one to each body, and so making them very long in order that they may take all the bevellings, but this is a very unhandy way in large ships, where a great number of people are employed, and being so very confused, occasion a great many mistakes. Others will have a bevelling board to every ribband and head, which is altogether as unhandy as the former

method; for then, when they want the bevellings for one futtock, they have to fly to six or seven boards before they can have them, besides sometimes taking a wrong board by mistake, and by that means spoiling the timber. Therefore the method we recommend would be, to have one bevelling board for every futtock, and likewise one for the floors, each containing every square timber in the body; the fore-body might be marked on one side, and the after-body on the other; then to take the bevellings for a floor, or a futtock, it would only be to look for the floor or that futtock bevelling board, where the bevellings would all appear regularly one after the other at one view, for their respective timbers, which might then be taken off with little trouble, and it would then be impossible to make a mistake, unless one timber were taken for another.

Provide a bevelling board for the floors, in breadth as much as the floor timbers are sided, and in length sufficient to take all the floor be vellings thereon. The first bevelling to be taken is from the cutting down line: therefore, beginning at dead flat, we shall find that to be a square, and also all the other midship timbers, which may be marked as such upon the board; then, apply the stock of a bevel to the next timber abaft the midship ones, keeping it beneath the cutting down line, and place the tongue of it well with the cutting down line, and that will give the bevelling for that timber; and proceeding the same with every other timber, all the bevellings may be taken, and may then be marked on the board, distinguishing them by writing their respective names upon every line; these bevellings will all be standing both in the fore and after bodies, and are for the purpose of trimming the throats of the floors.

In the next place, the bevellings for the outside of the floors must be taken, which are always under bevellings in both bodies, in consequence of the floors being always placed on that side of the joint that the body declines; those bevellings are the lower diagonal floor-ribband, and floorhead; and in order to take them from the body plan, proceed as follows: the bevelling board being parallèl, set off the breadth of it square from each timber aft, on each of the floor diagonals in the half-breadth plan; then, take the distance of each spot set off from the middle line of the half-breadth plan, and set them off on their corresponding diagonals, from the middle line in the body plan, making of spots; then take a pair of compasses, and place one foot in each of these spots, and sweep the other till it touches the nearest place of its corresponding timber, and the radius of that sweep will determine the bevelling of the timber at that place where taken, and shew how much it is under, or within a square, in the breadth of the bevelling board; the bevellings may then be taken in that manner for every sirmark upon every floor timber, and from thence may be marked on the bevelling board.

In the next place, provide other bevelling boards, one for each futtock, and one for the top timbers, observing to let the breadth of each be the siding of their respective futtocks or toptimber; then, in order to take the bevellings for each, we must act as before described for the floors, only observing which futtocks are standing bevellings, and which are under; as those which are standing the breadth of their bevelling board must be set off on the diagonal lines in the half-breadth plan, at the foreside of the timber for the after body, and the aftside of the timber for the fore body, and vice versâ for those which are under. (See Second

Futtock Diagonal in the Body and Half Breadth Plan, at Timber 24, Plate I.)

Therefore observe, the floors are under, first futtocks standing, second futtocks under, third futtocks standing, fourth futtocks under, and toptimbers standing, bevellings; the bevellings for which, at every diagonal and every timber, may now be taken, and marked on their respective boards, placing one body on one side, and the other body on the other.

The most essential particulars of laying-off, with respect to the canttimbers, differ from, and are not explained in, the methods of draughting heretofore given; but the principle admits, notwithstanding, of a verbal description; and, as this is a very material and essential branch of the art, we annex the following description and instructions with regard to this and some other operations, which will, we doubt not, be highly accept able to the young practitioner.

OF THE CANT TIMBERS,

In order to comprehend, clearly, the nature of the cant timbers, observe, firstly, in the half-breadth plans of Plate I. where the cant timbers intersect the middle line, at which place suppose them hung in a moveable manner, (as a door upon its hinges) and also suppose the line drawn for the cant timber u, to represent the upper edge of a large surface, the breadth of which shall be equal to the line of the cant timber, from the top of the ship to the upper edge of the keel; and, supposing the horizontal view of that surface to be represented by that one line, it immediately follows, that the surface must stand perpendicularly from the upper edge of the keel. If, therefore, we draw the proper shape of the cant timber, according to the shape given in the body plan, upon this surface from the keel to the top of the side (not moving its position) and then cut it out, we shall have the true position of the cant timber as in its place on the ship, which will stand in a perpendicular direction. We may also, (supposing it to be hung,) swing it either forward or aft, and it will still maintain its perpendicular direction.

The canting of the timbers is of great utility, as it contributes very much to the strength of the ship in the fore and after parts; and, likewise, greatly assists the conversion of the timber. For, in the first place, by canting the timbers gradually from a thwartship line, we thereby bring each timber nearer to a square with the planks of the bottom, which is not only better for the security of the planks, but the timbers are also more able to bear that security. And, secondly, were all the timbers to be placed square, as those of the square body, though the scantlings of the timbers on a square should be equal to the scantlings of the timbers if canted, yet the bevellings of the timbers will be so great, that the consumption in some places, in order to get the timbers clear of sap, would be greater by one half than that in the timbers which are canted.