APPENDIX 4 



Useful Data for Analysis and Comparison 



X4.1 General 926 X4.4 Conversion Ratios, English-Metric and 



X4.2 Customary Units of Measurement in the Metric-English 929 



English System 926 X4.5 Ratios of Ship Parameters and Coefficients . 930 



X4.3 Ratios Between English Units of Measure- X4.6 Frequently Used Numbers, Their Powers, and 



ment; Standard Values 926 Logarithms 932 



X4.1 General. Hydrodynamic analysis and 

 design can rarely proceed very far without getting 

 into the realm of numbers, for expressing magni- 

 tudes and intensities of one kind or another. 



The recent phenomenal growth in the avail- 

 ability of tabular material [Luke, Y. L., "Numer- 

 ical Analysis," Appl. Mech. Rev., Aug 1955, p. 

 310], prepared and published for the scientist and 

 the engineer in general, should find its counter- 

 part in an expansion of similar material for the 

 naval architect and marine engineer. This 

 appendix, taken in conjunction with Appendix 3, 

 is considered a minor but appreciable beginning 

 for both hydrodynamicist and marine architect. 



X4.2 Customary Units of Measurement in the 

 English System. It is customary, although not 

 universal, to express the magnitudes of all 

 important physical terms or concepts in units of 



some system of measurement. The units of the 

 English engineering system, listed in Table X4.a, 

 are used in this book unless indicated otherwise 

 for a particular case. 



The "consistent" units of the English system 

 are normally the pound, the foot, and the second. 



X4.3 Ratios Between English Units of Meas- 

 urement; Standard Values. Most of the ratios 

 between units used to express given concepts are 

 simple numbers, learned in elementary school. 

 Examples applying to the length concept are 

 1 yd = 3 ft and 1 mile = 5,280 ft. However, 

 certain other relationships are not so simple, nor 

 do they always remain fixed. One such ratio is 

 the number of degrees in a radian, represented 

 by 360/2ir = 57.2956, usually abbreviated to 

 57.3. Another familiar example is the number of 

 feet in a nautical mile. This ratio has had a 



TABLE X4.a — Customary Units of Measurement in the English System 



926 



