SHIP-BUILDING. 



particularlv thofc in the fervice of the Eall India Com- 

 pany. 



Tiie round-headed rudder is reprefented in the fheer-plan of 

 the Eaft India (hij), Plate XII., wliich confifts in making the 

 upper part of the rudder above, and fome inches below the 

 hoV- in ttiecnunicr, cylindrical, and giving that part, at the 

 fime time, a call forward above the upper brace, fo that the 

 axis of rotation nay by th^t means be the line palling, as 

 ufual, from the heel of the rudder to tlie upper brace, or that 

 next below ih; counter, and from thence upwards through the 

 axi>of the cyhndrical part. or head, in orderthat the tranfverfe 

 feftion at the counter may be a circle revolving upon its cen- 

 tre : in which ca(e the fpace of half an inch is more than 

 fufUcient between the rudder and the counter, and confe- 

 quently the neceflity of a rudder-coat entirely done away. 

 Ikit as it was forefeen, that if the rudder was by any acci- 

 dent unlhipped, this alteration might endanger the tearing 

 away of ihe counter, the hole is made from two to four 

 inches larger all round, according to the fize of the fhip, 

 than the tranfverfe ieftion of the cylindric part of the rudder, 

 but that fpace is eafily covered over with a wooden rim, about 

 two inches thick, and of fufficient breadth to nail to the 

 counter clear of the hole : this rim is fitted nearly clofe to 

 the rudder, and is capable of refilling the fhock of the fea, 

 but eafily carried away with the rudder, leaving the coun- 

 ter, under luch circumftances, in as fafe a itate as it would 

 be, agreeable to the prefent form of making rudders in the 

 navy. 



It is eafy to conceive that the braces cannot be carried up 

 fo high on the llern-poft with a round-headed rudder, as in 

 Plate I. But then the head is better Iteadied, as it has a 

 large bolt driven down through the centre, that traverfes in a 

 thick brafs plate confined in a ftrong oaken frame, fixed 

 over tlie head. 



It may alfo be readily feen, that to bring the axis of ro- 

 tation through the centre of the rudder-head, it mull call 

 fo much forward, as was before ohiervcd, which requires a 

 fudden hance between the upper brace and the counter ; 

 but to avoid this hance cutting away the main poll too much 

 at the head, a falfe poft, fufficientlv thick, is tabled or 

 coaked to the aft-fide of the main poll, as in Plate XII. 



The body and half-breadth plans may now be completed, 

 as it remains to add the fupernatant part, or top-fide. 



Transfer the heights of the top timber-line from the 

 fheer-plan, Plate I. to the body-plan, and draw an liori- 

 zontal line, at each height, acrois each refpcftive body. 

 Now the breadth of the Ihip at this height determines 

 the tumbling-homc of the top-fide, which Ihonld not be 

 too much, as formerly, as it creates an unnecefiary con- 

 fumption of crooked or compafs-tinibcr, or an extra- 

 vagant wafle of large timber, which muft be much weak- 

 ened by being cut acrofs the grain. Ag.iin, great ad- 

 vantages would be derived from having little or no tumbling- 

 home to the fides, as it gives more room upon deck, a greater 

 fpread to the Ihrouds, additional fecurity to the mails, 

 makes the fiiip llitfer, a much better fea-boat, and in every 

 refpcfl fafer, itroiiger, and better. On the contrary, it 

 may be argued, that by the top-fide tumbling-home, par- 

 ticularly in (hips of war, all the weight of guns, &c, 

 lying above the load-water-line, may thereby be brought 

 nearer to the middle line, when of courle the fliip will be 

 lefs ilrained by tlie working of her guns alfo ; but others 

 have endeavoured to prove, that by the weights being equal 

 on both fides, they counterpoife each other, and do not 

 llrainthe (flip, whatever diilance they may be removed from 

 the middle line. Again, the top-fide narrowing or tumbling- 

 liome, as it approaches the top of the fide, particularly in 



2 



(hips having two or three gun-decks, the fmokenf the lort-cf 

 guns in aftion lefs annoys thofe on the decks above. 



In Plate I. the top-tmiber breadth in midlhip is four feet 

 lefs than the main breadth, confequently the top-fide tumbles 

 home two feet on each fide, y.nd may be fo continued in the 

 half-breadth plan parallel to the mam breadth, from frame 

 2 2 abaft to H forward ; tlien from the middle line at K fet 

 up 2 I feet 1 1 inches ; at M, 2 I feet 8 inches ; at O, 2 I feet 

 6 inches ; at O, 2 1 feet ; at S, 20 feet 4 inches ; at U, 19 

 feet ; and at the beak-head, 17 feet : at 24, in the after body, 

 20 feet 7 inches ; at 26, 20 feet ; at 28, 19 feet 6 inche? ; 

 at 50, 18 feet 9 inches; at 32, iS feet; at ^4, 17 feet 2 

 inches ; at 36, 16 feet ; then to end it abaft, fquare down to 

 the half-breadth plan the interfefhion of the top timber-line 

 at the fide counter-timber in the flieer-plnn, and fet up, as 

 before, 12 feet. Then a fair curve-line drawn throuo-li 

 thefe fpots, reprefents the top-timber half-breadth. 



Transfer the top-timber half-breadths from the half- 

 breadth plan to their correfponding horizontal lines at the 

 top timber-line from the middle line in the body-plan. Now 

 the timbers may be formed above the lower height of 

 breadth in the body-plan, thus ; transfer the upper height of 

 breadth-line from the (heer-plan to the bocy-plan, drawing 

 thereat horizontal lines ; then fquare up the timbers already 

 drawn to interfeft the upper height of breadth refpeclively ; 

 open the compades to 15 feet, the length of the upper- 

 breadth fweeps, and fix one foot on each line lalt drawn ; 

 then from the lines, as fquared up, defcribe an arc of a 

 circle upwards at each timber; then draw at rf4 a curve to 

 the hollow of the top-fide, touching the back of the upper- 

 breadth fweep, and the breadth at the top timber-line, thus ; 

 the timber at the top-fide is formed in midlhip*, to which 

 let a mould be made from the upper height of breadth up- 

 wards, continuing the fame hollow of top-fide fonie feet 

 above the top timber-line at -f j by which mould all the tim- 

 bers of the top-fide, except two or three quite aft and for- 

 ward, may be drawn, and both bodies completed to the top 

 of the fide, by moving the mould at each timber gradually 

 upwards, fo as to make a fair line with the upper breadth 

 fweep, touching the breadth at the top timber-line. 



The foremoll frames, as X, U, and S, towards the top 

 of the fide, curve outwards, or the contrary way to thofe 

 abaft them ; becaufe the breadth at the toj) timber-line pro- 

 jcfts the main breadth below, by which the anchor is hove 

 up clear of the bow. From their breadth at the top timber- 

 line, fquare up a perpendicular line to the top of the fide, 

 which produces , a ludden angle or knuckle at the top 

 timber-line, from nhence they are called Lnucklc-limlers. 



From tlie fheer-plan transfer the heights of the top-fide to 

 their refpeclive timbers in the body-plan, and draw a curve 

 line through thofe heights, and the top of the fide will be 

 reprelcnted in the body-plan. Then, to prove that the heads 

 of the timbers make a fair longitudinal curve, transfer tlieir 

 half-breadths at the height of the top-fide in the body-plan 

 to their refpeftive timbers in the half-breadth plan ; that is, 

 from frame D forward, and from 10 abaft ; if they produce 

 iair curves, the top of tlie fide is correct. 



Now the fide fierii-timber may be drawn in the body-plan, 

 thus: transfer the height of the wing-tranfom, lower coun- 

 ter, upper counter-knuckles, top timber-line, and top-fide, 

 from the fide ilern-timber in the (heer-plan to the after 

 body-plan, and draw an horizontal line at each height ; draw 

 likewife two horizontal lines, equally fpaced, between the 

 wing-tranfom and lower counter-knuckle, and one equally 

 between the upper counter-knuckle and the top tnnbir-liiie. 

 Transfer the half-breadths of the (\ti. after-frames, where 

 they are interfcfted by the above horizontal lines, to their 



corrc- 



