SHIP.BUILDING. 



true principles upon which the conftruftion of (hips, fo as 

 to anfwer the particular purpofes of war or commerce, is 

 founded, muft conduce to remedy all the prefent defefts, to 

 render the theory more perfeft, and enable the Englilh 

 artifts to become as eminently Ikilful in the fcientific, as 

 they now confelfedly are in the praftical branches of fhip- 

 building. 



In order to fmooth the way in a fcience thought fo incom- 

 prehenfible, our readers muil be made familiar with the 

 feveral draughts and plans requifite to conftruft and raife fo 

 noble a body of architefture ; for the proportional fize of 

 every part muft be laid down, from whence the form and 

 dimenfions of the feveral timbers, and every particular part 

 that enters into the conltruttion, are to be obtained. There- 

 fore, as a fhip has length, breadth, and depth, three dif- 

 ferent plans at lealt are neceffary to reprefent the form of 

 the feveral parts of her ; as in the (heer-draught, Plate I. 

 of Ship-building, which comprehends the (heer-plan, the body- 

 flan, mA ihehalf-breaJlh plan. 



The Jhecr-plan, or, as it is called in civil architefture, the 

 plan of elevation, is a vertical feftion, palling through the 

 veflel in its whole length, or fore and aft. Upon this plan 

 the length and depth of the keel are reprefented, alfo the 

 height and rake of the ftem and ftern-poft ; the fituatiou 

 and height of the midfhip and other frames ; the water- 

 lines ; heights of the decks, gun-ports, and wales; the centres 

 of the mails ; the fituation of the channels ; length and 

 depth of the head and rails, quarter-galleries, rudder, 

 &c. &c. 



The body-plan, or plan of projeSion, to the left of the 

 fheer-plan, is a tranfverfe feftion of the fliip at the midfhip. 

 frame, or broadeft place perpendicular to the keel. The 

 feveral breadths, and the particular form of every frame- 

 timber, are defcribed on this plan. Now as the two fides 

 of the fhip are, or fliould be, exaftly fimilar to each other, 

 it is therefore unneceilary to reprefent both : hence the 

 frames contained in the fore-body, between the midlliip-frame 

 add the ftem, are defcribed on the right-hsnd fide of the 

 middle line, and the aftermoft frames on the left of the faid 

 middle line. 



The half-breadth or floor-plan, under the (heer-plan, and 

 parallel thereto, or as it is frequently called, the horf^ontal 

 plan, contains the feveral half-breadths at every frame- 

 timber, at the different heights of the water-lines, main- 

 breadth, top-fide, ribband-lines, &c. 



The confideration of thefe three principal plans is fo 

 much the more important, as it comprehends a fufficient 

 knowledge of the figures of all vefTels. For although thefe 

 three plans do not really determine the figure of the veffel, 

 and may belong to an infinity of different kinds, yet all 

 thefe differences cannot exceed certain limits fufficiently con- 

 fined ; fo that whatever idea we might form of the figure of 

 the veffel, it cannot deviate confiderably from the truth. 



In order to explain this better, we will proceed to con- 

 ftruft the (heer-draught, Plate I.; and here the nature, and 

 all the properties of the veffel, according to her defign for 

 war or commerce, muft be taken into confideration, upon 

 which the whole theory of the art depends : fuch are, capa- 

 city, ftability, velocity, and eafe in the fea or at anchor. 

 Thefe properties are not to be adopted merely from fpecu- 

 lative theory, but from thofe that have aftuallybeen demon- 

 ttrated by repeated experiments. That our readers may 

 have the cleareft conception of the various parts of a 

 fhip, reprefented by the plates of the 74-guii fhip, we 

 will endeavour to defcribe them in as familiar a manner as 

 pofGble, introducing alfo all that is neceffary to be known as 

 we proceed. The 74-gun fhip is preferred as the medium 



between the firfl-rate and the frigate, and is efleemed the 

 moft ufeful of all others. 



Therefore, the firft thing to be determined is the length 

 on the gun-deck ; and here fufficient dittance muft be 

 allowed for the ports, which are fifteen in number, three 

 feet five inches wide, or fore and aft, each, fo as to hare 

 a fufficient diftance between each port for working the 

 guns, which is about feven feet eight inches ; likewife 

 room forward, between the foremoft-port and the ftem, for 

 the manger ; and alfo abaft the after-port, to the tranfoms ; 

 thefe confidered make the length on the gun-deck 180 

 feet. 



Draw therefore, as in (heer-plan, Plate I., a ftraight line, 

 which reprefents the upper edge of the keel, and in naval 

 (hips the upper edge of the rabbet (Eait India (hips and 

 mcrchant-fhips in general have the rabbet in the middle of 

 the keel), leaving under this line fufficient fpace for the 

 main and falfe keels, fcale, and half-breadth plan. Upon- 

 this line fquare up a perpendicular towards the right hand, 

 leaving a fufficient fpace to reprefent the head, and call it 

 the foremoft-perpendicular ; then, at 22^ inches abaft it, 

 fquare up the after-perpendicular, which is 180 feet, by 

 one-eighth of an inch to a foot, or the length on the 

 gun-deck, from the aft-fide of the rabbet of the ftem to the 

 fore-fide of the rabbet at the ftern-poft. Below the upper 

 edge of the keel, and parallel thereto, fet down two feet 

 for the main and falfe keel, and under it draw the fcale of 

 equal parts, of one-eighth of an inch to a foot, and from 

 this fcale fet off all the following dimenfions. Obferve, 

 draughts in general are drawn from a fcale of one quarter 

 of an inch to a foot, but this, for convenience, to ene- 

 eighth. 



The length between the foremoft and aftermoft perpendi- 

 culars, in merchant-fhips, is given from the aft-fide of the 

 ftern-poft, at the height of the wing-tranfom, to the fore-fide 

 of the item, at the lame height. 



The ftem, or fore-boundary of the fhip, may now be drawn, ' 

 and a fegmcnt of a circle for its lower part has long bees 

 confidered as the beft form for dividing the fluid ; therefore, 

 fix its centre fo that the aft-fide of the rabbet (which is in 

 the middle of the ftem, towards the upper part) may inter- 

 feft the foremoft-perpendicular at the height of the gun- 

 deck ; thus, fet aft from the foremoft-perpendicular, as in 

 Plate I. upon an horizontal line, 24 feet above the upper 

 edge of the keel, 24 ft. 3 in. ; and from thence, as the centre, 

 draw an arc of a circle from the upper edge of the keel- 

 line, and another arc 18 inches before it, from the fame 

 centre ; then will the moulding, or fore and after-fides 

 of the ftem, be reprefented : fweep likewife the rabbet, 

 as in Plate I.; then fet up 36 feet for the height of the 

 head of the ftem, and at that height fet forward 15 inches 

 from the foremoft-perpendicular ; from thence draw a faint 

 curve, to interfeft with the foremoft fegment, and the 

 fore-part of the ftem will be fhewn : continue upwards an- 

 other parallel thereto, and the aft-fide or whole ftem is com- 

 pleted, except the lower end or boxing, which will be de- 

 termined hereafter. 



The itern-poil, or after-boundary under water, may be 

 next drawn ; thus, fet up from the upper edge of the keel- 

 line 26 ft. 10 in., which is the upper fide of the wing-tran- 

 fom at the after-perpendicular, and upon that line fet aft 

 from the perpendicular I ft. 10 in., and upon the upper edge 

 of the keel, fix inches before the after-perpendicular; then 

 a line drawn through thefe points will reprefent tlie aft-fide 

 of the ftern-poft ; another fine, drawn at fourteen inches be- 

 fore the aft fide of the ftern-poft, at the wing-tranfom, and 

 at two feet one inch on the upper edge of the keel, will be 

 II the 



