R = . A + . S 



A S 



To simplify the use of the contours, a nomograph is given in Apf)endix B from which the 



R p 

 frictional resistance per square foot of wetted surface can be determined. Contours 



S 

 are also given for estimating the wetted surface for any combination of design parameters. 



The (C) - (k) contours are for the total resistance, residuary plus frictional, and the 



© values are those appropriate to a ship of 400 ft LBP. For any other length, a correction 



o 



must be made which depends upon the actual length and the wetted surface coefficient . 



V2/3 



For those who wish to compare the Series 60 (C) values with those of other models 

 in which the Froude values of 0^ and 0^ have been used in the analysis, a rapid method of 

 making the conversion has been given by Gertler,'*^ See also Appendix D. 



In the(0 charts and the nomograph for determining , an allowance for ship correla- 



o 



tion amounting to +0.0004 has been made in accordance with the ATTC 1947 recommendation. 

 Calculation forms for finding the (0 400 ft and ehp values for any single-screw merchant 

 ship having lines derived from the Series 60 contours and proportions within the range 

 covered by the Series are also given in Appendix B. Methods are also described there for 

 calculating (c) for a ship of other than 400-ft length and for including a ship correlation 

 allowance C^ having some value different from +0.0004. Although the calculation forms are 

 largely self-explanatory, a numerical example is worked out in Appendix D to clear up any 

 difficulties still remaining after reading the text. 



As stated on page V-14 the ITTC agreed in 1957 to the use of a new "model-ship 

 correlation line" in future published work. However, pending some agreement on a standard 

 ship correlation allowance to be associated with the new line, it has not yet come into 

 general use. The ITTC and ATTC lines differ both over the model and ship ranges of 

 Reynolds number, and so affect the division of the model resistance into its "frictional" 

 and "residuary" components, as well as the values of the corresponding ones for the ship. 

 It is thus not merely a question of using different values of R^.; all the values of residuary 



resistance — — will be different also. Som.e riotes and an additional nomograph are given 

 in Appendices D and E for readers who may wish to make estimates using the ITTC line. 



IX-2 



