300 



HYDRODYNAMICS IN SHIP DESIGN 



Sec. 56.4 



for Cp values of 0.48 through 0.80, are shown in 

 Fig. 51. A, based upon data from the following 

 references: 



(1) S and P, 1910, Vol. II, Figs. 79 and 80 



(2) S and P, 1933, Figs. 70 and 71, p. 191 



(3) PNA, 1939, Vol. II, Fig. 28, p. 92 



(4) S and P, 1943, Figs. 184, 185, and 186, pp. 182-183. 



The end results, in the form of contours of 

 residuary resistance Rr in pounds per ton of 

 displacement A for the given proportions, were 

 pubhshed in the three editions of "The Speed 

 and Power of Ships," as noted: 



1910, Vol. II, Figs. 81 through 120, covering a range of 

 r, from 0.60 through 2.00, for two B/H ratios, namely 

 2.25 and 3.75, and for various ranges of displacement- 

 length quotient and prismatic coefficient 



1933, Figs. 72 through HI, pages 193 through 271, 

 covering the same range of Tq , A/(0.010L)', and Cp as 

 for the 1910 edition 



1943, Figs. 189 through 240, pages 189 through 240, 

 covering a range of Tq of from 0.30 through 2.00, with the 

 other variables remaining the same. 



Two sets of contours from the latter reference 

 are reproduced in Figs. 56. A and 56. B. They were 

 selected to fit the ABC ship example of Sec. 57.6. 



To use these contours, values of Rr/A are: 



(a) Picked from two sheets for a B/H ratio of 

 2.25, (1) for a speed-length quotient just below 

 that desired and (2) for a speed-length quotient 

 just above it. The contours are entered with the 

 Cp value along the horizontal scale and the 

 A/(0.010L)' value along the vertical scale. 



(b) Picked from two sheets for a B/H ratio of 

 3.75, (1) for speed-length or Taylor quotients 

 just below and (2) just above the desired value. 

 These are the same T, values as for (a) preceding. 



The correct value of Rr/A is then found by 

 linear interpolation first, between the B/H ratios 

 of 2.25 and 3.75, and then between the two speed- 

 length quotients. 



To illustrate this procedure an example is 

 worked out in Sec. 57.6 and Table 57. b for the 

 transom-stern ABC ship having the preliminary 

 characteristics listed as the fifth approximation in 

 Table 66.e of Sec. 66.11. 



56.4 Japanese Fishing- Vessel Standard Series. 

 Because the Taylor Standard Series extended 

 only to a maximum displacement-length quotient 

 of 250, corresponding to a 0-diml fatness ratio 

 V/iO.lOLf of 250/28.51 or 8.77, it could not be 

 used for predicting the performance of fat, chubby 

 ship forms such as those of tugs, fishing vessels, 



and icebreakers. During the years 1946-1949 a 

 group of Japanese, Atsushi Takagi, Takao Inui, 

 and Shoichi Nakamura, undertook the testing of 

 a standard fishing-vessel series covering 0-diml 

 fatness ratios of from 6 through 15, corresponding 

 to a range of Taylor displacement-length quotient 

 of 171 through 428. The B/H values were 2.2 and 

 3.0, while the Cp values were 0.55, 0.60, 0.65, 

 0.70, and 0.75. The range of Froude number F„ 

 was 0.16 to 0.38, corresponding to a T^ of 0.537 

 to 1.28. 



Following their procedure of putting all param- 

 eters in 0-diml form, the Japanese plotted contours 

 of specific residuary resistance C„ , where C„ = 

 Z?^/(0.5pV'^'F'). The data were published in 

 final form in 1950 by the Fisheries Agency of 

 Japan in a book entitled "Graphical Methods for 

 Power Estimation of Fishing Boats." 



-10 y 



SCALEtoPRISMATIC ODEFHCENT if 



Fig. 56. C Typical Sheet of Contours of Residuary- 

 Resistance Coefficient for Japanese Fishing- 

 Vessel Series 



Fig. 56. C is a reproduction of one of the contour 

 sheets of this book, suitable for estimating the 

 Cr values for the European fishing-boat model of 

 J.-O. Traung, shown in Fig. 76. G. In this sheet 

 the Japanese B/T, C, , and </)(phi) expressions 

 correspond to the B/H, C r , and Cp expressions 

 in the present book. 



Unfortunately, the parent form selected for 

 the Japanese fishing-boat series has too large a 

 prismatic coefficient and gives a rather indifferent 

 performance. It is possible to improve upon it in 

 modern designs by as much as 10 per cent by 

 lowering the Cp value from 0.70 to the order of 

 0.58. Furthermore, the models tested were not 



