198 



1IM)R()|)N\ \\ll( s |\ Mill' 1)1 s|(;\ 



Sec. 19.1 1 



Port of Dio^rom on Film Overlay Carruinq 

 Circles of Corvotore of Venous Rodii 



Parollel 

 Portion of Line 



Lenqlh in Inches of o l-Deqree Arc on Eoch Circulor Arc 



\ \ 



Rodiu» of Circle of 



IS Somewhat Smoller 

 than the Correct Value. 

 to Make It Visible 



-^- 



.Lenqth of 

 This Rodius \ l-Deqree 

 \of Curvoture \ '^"' "<• "^^ » 

 ^ij Infinite \ ''«""*■ '» 

 0.10 in 



Circle of Curvoture 



Beam Bi 

 ts 5.49 in 



0-Diml 

 Curvature! 

 5.49/0O I 

 ■0 



Fig. 49.F Instruction Plan foh Determining 0-Diml, Curvature ok any Ship Line 



beyond the bow (or stern). It appears advisable 

 in this ca-se to terminate the plot at a point where 

 the circles of curvature no longer fit, say at about 

 0.02oB.r on each side of the centerline. 



A legible waterlinc drawing of any scale may be 

 analj'zed, -provided the longitudinal and transverse 

 scales are identical. Although the circles of curva- 

 ture are fitted by eye to the cur\-e underneath, 

 this graphic method is extremely sensitive to 

 sudden changes in curvature, unfairness, and 

 inaccuracies in the ship line being analyzed. 



For determining the 0-diml longitudinal curva- 

 ture of a bow line or buttock the procedure is 

 exactly the same as described for the watcrline. 

 However, instead of the maximum beam Bx , the 

 traiKWerse Uncar dinicnsi(jn in the numerator is 

 luncc the maximum depth from the DWL to the 

 lowest point of the buttock measured on the 

 drawing. This corresponds to the existence of a 

 mirror image of the ship above the DWL, and 

 to measuring tht; traiisvcr.sc! dimension from the 

 highest to the lowest point.s of the imagc-aiui-ship 

 combination. 



For any diagonal on the ship lines the transverse 

 linear dimension in thf numerator is taken as 



tufire the maximum diagonal offset on the drawing, 

 measured along the diagonal trace from its 

 intersection with the plane of symmetry. This is 

 equivalent to the waterline-analysis procedure 

 if both port and starboard diagonal i)lancs are 

 swung upward about the centerplane inter.section 

 so as to coincide at the plane of the watcrline at 

 that intersection. 



49.11 Mathematic Delineation and Fairing of 

 a Section-Area Curve. Those working on tlie 

 analytic phase of wavemaking resistance, develop- 

 ing methods whereby tiiis resistance may be 

 calculated for certain .shij) forms, have endeavored 

 to determine the effect on ship resistance of the 

 distribution of volume along the length. This 

 distribution is shown l)y the ortiiodox section- 

 area or /l-curvc, described in Sec. 24.12 and 

 illustrated in Fig. 24. F. Indeed, the optimum 

 form of .l-curve, for minimum resistance, has 

 l)ecn found for a soit of geometric sliij) having 

 rectangular .sections througliout and moving in a 

 non-viscous licpiid ISN'.VMi;, lit").!, Kig. ;i.S, p. 

 582]. 



SupplcniiMitiiig this wiirk, P. (,'. I'icii has 

 ileveloped malliriuatic section-area curves wliicli 



