Hf ^1/3 Rj. 



and © = -7- • X 1000 = x 2938 



■^ (0.5834-F)2 A2/3 . 72 



whore R and A are both in tons or, in terms of horsepower, 



©= _HLx 427.1 



^2/3^3 



A presentation of resistance data in the ©-® system is therefore compatible and 

 places models or ships in a correct merit order. In the design of a merchant ship, the two 

 principal basic design factors are the speed and displacement— how much displacement (and 

 therefore deadweight) has the ship to carry at a given speed? The ©-® system involves 

 only V and A and leaves length along with other dimensions and coefficients among the 

 variables which are at the designer's disposal in attempting to find that combination which 

 will result in the most economical overall design. 



From the various charts and tables presented in this report, the designer can extract 

 the data he desires in either form, according to his needs and in keeping with the method 

 with which he is most familiar or in which his own data are recorded. The conversion of the 

 @ data using the ATTC line, as given in this paper, to the equivalent © data using Froude, 

 or vice versa, can also be quickly made by the use of the chart given in Appendix D (Figure 

 D-4), thus giving a connecting link with the large quantity of © data in existence in this 

 form. 



XII-15 



