II 



SHIP-BUILDING. 



..flrufted, Vi'lien the radii of the floor-fwccps alter much 



their length. 



Neither the rifing-line in the (hccr-plan, nor the half- 

 breadth of the rifing, would continue to be the curves as firll 

 conftrufted, if the form of the body firll defigned were to be 

 altered in that part. It is evident, then, that the rifing-line 

 may be drawn according to the judgment of the artill in the 

 conftruftion of any draught, obferviug to make it a fair 

 elliptical curve, (tor much depends on the conllruftion of 

 the lower part of the body,) by judicioufly narrowing the 

 floor-fweep, or half-breadth of the rifing ; for the more pa- 

 rallel it is kept with the middle line, the lefs will be the ve- ' 

 locity of the (hip. Again, the quicker this curve is, the lefs 

 bearing will the fliip have ; and though it may be fuppofed, 

 when the rifing-line is formed in the (hecr-plan, and likewifc 

 its half-breadth, it is reafonable to expecl a fair body, yet we 

 cannot be certain of its producing that form of body which 

 is really intended agreeable to the ufe which the (hip is de- 

 figned for, unlefs by frequently defigning of bodies we can 

 form an exadl idea before we proceed. Therefore the young 

 artilt Ihould improve himfelf by drawing bodies conftrufted 

 by the rifing-line of (hips of different properties, till he forms 

 in his own judgment a perfeft idea of this mode of conftruc- 

 tion. For inftance, if it be required to make the fliip cleaner, 

 lift the rifing-line in the (heer-plan, and narrow its half- 

 breadth ; and where it may be required to make the fhip fuller, 

 lower tlie rifing-line in the (heer-plan, and increafe its half- 

 breadth ; which fufficiently proves that the rifing-line is as 

 ■variable as the different forms of (hips' bodie:^ may require. 

 See for fulnefs the plate of the Eall India (hip, the plate of 

 the 74-gun fhip, which is ftiarper, and alfo the frigate of 

 40 guns, wliich is (harper (till ; and we (hall then find it a very 

 complete method ot conltruCting the lower parts of (ucli 

 fhips fair, particularly thofe that require fome provifion or 

 fulnefs of body to atiill them in taking the ground. The 

 further forward and aft the body is allilted by the lifing- 

 line, the more merit there will be in tlie conllruftion, and 

 the greater certainty of producing a fair body : notwith- 

 ftanding all this, fome bodies are conftrufted without any 

 floor-fweeps, which muft be the cafe in very fliarp bodies, 

 fuch as cuttere, &c. 



It may be further obferved, that the rifing-line cannot, 

 from its nature, be formed by any regular proportional 

 method, from which there can be no variation without 

 impropriety; nor can it be conftrufted to any fixed 

 proportion, unlefs fhips of different clades were built ex- 

 aftly timilarto each other, becaufe the riiing-line in fhips of 

 war, and thofe wliicli are conftrufted for velocity, though 

 fuitable to the conllruftion of the lower part of cich fhip, 

 and likely to anfwer the purpofc for whicli they are de- 

 figned, cannot be equally proper for ftiips ot the fame length 

 and breadth, if required chiefly for burden ; as in ihelaft cafe 

 not only the form of the mid(hip-bend, but every part of 

 the bottom muft be differently formed, which will be clearly 

 feen by examining the plates of the 74 and 40-gun (liips, 

 and the plate of the Eaft India fhip, which was found to an- 

 fwer admirably well. 



Whole-moulding was formerly a method nf conftruftiiig 

 the immerfed part of (hips' bodies, by the mould beuig made 

 to the form of the midfhip-bend, which, with the addition 

 of the floor-holiow, would mould all the timbers below the 

 main-breadth in the fipiare body. But fince the art of fliip- 

 building has arrived to its prefent perfeftion, the method of 

 whole-moulding, for the following reaions, has been jullly 

 laid afide. For by whole-moulding, 110 more is narrowed at 

 the floor than at the main-breadlh, that is to fay, the curves 

 of each are kept parallel; nor mull tiic rifing-line in the 



ftieer-plan lift any more than the lower height of breadth ; 

 which, according to the form of fome midfliip-bcnds, would 

 make a very ill-con(lrufted body; for by continuing that 

 nearly forward and aft, the (hip would not only be incapable 

 of rifing in a heavy fea, but be deprived in a great meafure 

 of the more advantageous ufe of her rudder. Neverthelefs 

 this method is ftill continued in the formation of boats. 



Proceed now to draw the plan of projtftion, or body- 

 plan, thus : continue the line at the upper edge of the keel 

 beyond the after-end of the (heer-plan, as in Plate I., and 

 fquarc up a perpendicular for tlie fide-line of the fore-body, 

 obferving to keep it clear of the ftern ; from that perpendi- 

 cular fet off 48 feet, the (hip's main breadth at dead-flat, 

 and fquare up another perpendicular for the fide-line of the 

 after-body, and equally between both fquare up another 

 perpendicular, which is the middle line to both bodies re- 

 fpectively ; then the line prolonged from the upper edge of 

 the keel is the bale line of the body-plan. Draw in the 

 horizontal lines, as may be feen in the body-plan, Plate I. 

 at the lower heights of breadth, by transferring their heights 

 from the flieer-plan at the fevcral frame-timbers : thofe before 

 the dead-flat, fet up in the body-plan to the right of the 

 middle line, which arc to reprefent tlie fore-body, and thofe 

 lieiglits abaft dead-flat, to the left hand for tlie after-body. 

 Then from the half-breadth plan take the main half-breadth of 

 each frame, and fet it off from the middle line in tlie body- 

 plan, upon its correfponding height of breadth-hne ; and 

 from thence fet ofi' towards the middle line the length of 

 their rcfpeftive lower-breadth fweeps : thus, to defcribe the 

 midfhip-timber, or dead-flat, extend the compafl'es to 18 feet 

 6 inches, the radii of lower-breadth fweeps at dead-flat, and 

 draw part of a circle downwards, interfefting its main 

 breadth at its horizontal height. 



Then the centre heights of the floor-fweeps in the body- 

 plan muft be taken from the curve-line reprefenting their 

 heights in the fheer-plan, which at dead-flat will be found to 

 interfeft the upper edge of the keel ; but in the body- 

 plan, its height at dead-flat is 1 1 feet 6 inches, and there an 

 horizontal line is drawn to the diftance of the centre, or its 

 half-breadth from the middle line, and all the heights of 

 centres are refpeftively fet upwards above this line, on per- 

 pendiculars fquared upwards at the half-breadth of the centre 

 of each floor-ivveep of its correfponding frame or timber, as 

 taken from the half-breadth plan ; and the reafon for not 

 keeping the faid curve-line or heii;hts in the fheer-plan as in 

 the body-plan, i^ becaufe it would interfere with the curve- 

 lines above. Now by infpefting Plate I. it will be readily 

 feen, that by raifing tlie heights of thofe centres in the fheer. 

 plan, confequently in the body-plan, and by narrowing their 

 halt-breadths in tiie half-breadlli plan, liicir centres would be 

 brought nearer the middle line in the body-plan, the floor- 

 rifing would become quicker, and the fliip have lefs bearing, 

 and vice ver/,1, more full and burthenfome : thus mull the 

 rifing and narrowing of the centres be adjulledlill the body 

 of the vedel iias the capacity required for whatever fcrvice 

 (he may be defigned. 



Uut as in this mode of conllruftion the centres only, and 

 not tlie length of the floor-fweeps, are given, a diagonal rib- 

 band muft be drawn in the half-breadth j)lan, as 111 /'/ate I., by 

 letting oft' from the middle line at ®, 16 fei.1 ; at D, 15 feel 

 (J inches ; at D, 15 feet 5 inches ; at F, 1 5 feet l inch ; at H, 

 14 feet 7 inclies; at K, 14 feet ; at M, 13 feet -.J an inch ; at 

 O, I 1 feet 1 1 inches ; at Q, 10 feet 4 inches ; at S, 8 feet 

 6 inches ; at U, 6 feet i inch ; and at X, 2 feet j inches. 

 Then in the after-body let oft at 2, 15 feet 11^ inches; at 

 4, I J feet I oi inches ; at 6, 1 5 feet 9 inches ; at 8, 15 feci (\ 

 inches; at 10, 15 feet 4 inches ; at 12, 15 feci 1 inch; at l^, 



14 feet 



