BOA 



BOA 



Draw theftraight line VO,Jg. i. Pftrtel. {Ship liiMMg) 

 eqvial to 31 feet, tht extrtrnie lcnj(th of tlie bo;it, and alio 

 to reprefent the upper edge pf the keel. Let © be the 

 ftation of the midfhip frame. From the points P, 0, and 

 O, draw the lines PT, ©M, and OS, perpendicular to PO. 

 Make ©M, ©N, equal to the upper and lower heights of 

 breadth refpedlively at the main fra:r.e, PT, the height of 

 breadth at the tranfom, and OS, the height at the liern. 

 Defcribe the curve IMS, to reprtlcnt the flieer, or extreme 

 height of the lide, which, in a fliip, would be called either 

 the upper height of breadth line, or the upper edge of the 

 wale. Through the point N draw a curve parallel to 

 TMS, to reprefent the breadth of the upper drake of a boat, 

 or lower edge of the wale, if in a fliip. The dotted liiie 

 TNS may alfo be drawn to reprefent the lower height of 

 breadth. 



Set off the rake of the poft from P iop, and draw the line 

 pt, to reprefent the aft fide of the pofl ; then 'Yt will repre- 

 fent the round up of the tranfom. Set oif the breadth of 

 the poll from p to r, and from T to s, and draw the line rs 

 to reprefent the forefide of tl'.e poll, which may either be a 

 curve or a ftraight line at pleafure. Set up the height of the 

 tuck from/) to k. Let Lx be the thicknelo of the tranlom, 

 and draw the line Z .v to reprefent the fore fide of the 

 tranfom. 



There is given the point S the height of the Iheer on 

 the forefide of the Item ; now that fide of the ftem is to 

 be formed either by fweeps, or fome other contrivance. 

 Set off the breadth of the ftem, and form the aft fide 

 of it. 



Set up the dead-iifing from © to </, and form the rifing 

 line ris. Draw the line KL parallel to PO, to reprefent 

 the lower edge of the keel, and another to reprefent the 

 thicknefs of the plank or the rabbet. The rabbet on the 

 poft and ftem may alfo be reprefented ; and the ftalions of 

 the timbers affigned, as ©, ( i ), 1,2, 3,4, 5, 6, 7, 8, 9 ; and 

 ©, (A), A, B, C, D, E, F, G, H ; and the !heer plan will 

 be completed. 



The half-breadth plan is to be formed next ; for this pur- 

 pofe the perpendiculars TP, 9, 8, Sic. mult be prodi.ced. 

 Upon M© produced fet off the half-breadth from the line 

 KL to R (Jig. 2.) : fet off alfo the half-breadth at the tran- 

 fom from K to i, and defcribe the extreme half-bread.h line 

 ^RX, making the fore-part of the curve agreeable to the 

 propofed round of the harpin. 



We may next proceed to form the timbers in the body 

 plan. Let AB fjig. 3.) be the breadth moulded at @. 

 Lrect the perpendicular CD in the middle of the line AB, 

 draw the line mn diftapt therefrom the half thicknefs of the 

 poft, and xy the half thicknefs of the ftem. Then take oft" 

 the feveral portions of the perpendiculars ©, 1, 2, Sec. inter- 

 cepted between the upper edge of the keel and the rifing 

 line in the llieer plan, and fet them up from C upon the line 

 CD; through thefe points draw lines parallel to AC ; take 

 off alfo the feveral lower heights of the breadth at @, I, z, 

 &c. frc m the Iheer ]j\^n ; and fet them up from C upon the 

 middle line in the body plan ; and draw hues parallel to AC, 

 through thefe points ; then take off the feveral halt-breadths 

 correfpondir.g to each from the fioor plan ; and fet them off 

 on their proper hall-breadth lines, from the middle line in the 

 body plan. 



Conftruft the midftiip frame according to the directions 

 mentioned in that article, the form of which will in lome 

 meafurc determine the form of the reit. For if a mould be 

 made on any fide of the middle line to fit the curve part of 

 it, and the rifing line, or that marked tend mould, (Jig. 4.) 

 and laid in fuch a manner that the lower part of it, which is 



ftraiglit, may be upon the feveral rifing lines, and the upper 

 part juit touch the point of the half-breadth in the breadth 

 line corrcfponding to that rifing upon which the mould is 

 placed, a curve may then be drawn by the mould to the rifing 

 line. In this manner we may proceed fo far as the rifing 

 line is parallel to the lovver heiglit of the breadth line. Then 

 a hollow mould muft be made, the upper end of which is left 

 ftraight, as that maiked holioiu mould (Jig. t^..). This is ap- 

 plied in fuch a manner, that tome part of the hollow may 

 touch the fide of the keel, and the ftraight part touch the 

 back of the curve before dcfcribed by the bend mould ; and 

 beginning abaft, the ftraight part will always come lovver on 

 every timber, till we arrive at the midfhip timber, when it 

 comes to the fide of the keel. Having thus formed the tim- 

 bers, as far as the whole mouldings will ferve, the timbers 

 abaft them are next formed. Their half-breadths are deter- 

 mined by the ftieer and floor plans, which are the only fixed 

 points through which the curves of thefe timbers muJl pafs. 

 Some form thefe after timbers before the whole is moulded, 

 and then make the hollow mould, which will be ftraighter 

 than the hollow of either of thefe timbers. It is indifferent 

 vrhich are firft formed, or what methods are ufed : for after 

 the timbers are all formed, though every timber may appear 

 very fair when confidered by itfelf, it is uncertain what the 

 form of the fide will be. In order to find which, we muft form 

 feveral ribband and water lines ; and if thefe do not make 

 fair curve?, they muft be reilified, and the timbers formed 

 from thefe ribband and water lines. In ufing the hollow 

 mould, when it is applied to the curve of each timber, if the 

 ftraight part is produced to the middie line, we ftiall have as 

 many points of interfeftion as there are timbers ; and if the 

 heights above the bafe be transferred to the corrcfponding 

 timbers in the fheer plan, a curve paffing through thefe 

 points is called a rifing Jlrait . This may be formed Ijy fixing 

 a point for the aftermoft timber that is whole moulded, and 

 transferring that height to the flieer plan. The curve mult 

 pafs through this point, and fall in with the rifing line fome- 

 where abaft dead-flat ; and if the feveral heights of this line 

 be transferred from the ftieer to the middle line in the body 

 plan, thefe points will regulate what is called the hauling 

 down of the hollow mould. 



The timbers in the after-body being all formed, thofe in the 

 fore-body are formed in the fame manner, by transferring the 

 feveral heights of the rifing and breadth lines from the ftieer 

 to the body plan ; the half-breadths corrcfponding to each 

 height muft alfo be transferred from the floor to the body 

 plan. The fame hollow mould will ferve both for the fore 

 and after-body ; and the level lines, by which the water lines 

 to prove the after-body were formed, may be produced into 

 the fore-body, and by thefe the water lines to prove the fore- 

 body may be defcribed. 



Another method of proving the body is by ribband lines, 

 which are formed by fedtions of planes inclined to the flieer 

 plan, and interlefting the body plan diagonally, as before ob- 

 ferved, of which there may be as many as may be judged ne- 

 ceffary. In this, four ribband lines are laid down, marked 

 diag. which are drawn in fuch a manner as to be perpendicular 

 to as many timbers as conveniently may be. After they are 

 drawn in the body plan, the feveral portions of the diagonal, 

 intercepted between the middle line and each timber, muft be 

 transferred to the floor plan. Thus, fix one foot of the com- 

 pais in the point where the diagonal interfeds the middle 

 line in the body plan, extend the other foot to the point 

 where the diagonal interfedts the timber, for example, timber 

 9. Set off the fame extent upon the perpendicular repre- 

 ienting tlie plane of timber 9, from the point where it inter- 

 fetts the line KL, on the floor plan ; in like maiiacr proceed 



with 



