Lewis 



Also wave bending moment, if expressed in non-dimensional form, may be di- 

 vided by wave slope, giving [11]: 



h^A 



277L/^ 



where h^ is effective wave height and h^A is a non-dimensional bending mo- 

 ment coefficient, 



cpgL'BC 



where 



M^ is wave bending moment in irregular sea (such as average or highest 

 expected value in 10,000 cycles), 



C is a static bending moment coefficient = static wave bending moment in 



L/20 wave/pgL^B(L/20)C^, 



p is mass density of water, 



g is acceleration of gravity, 



L is ship length, 



B is ship breadth, 



C^ is waterplane coefficient. 



An important step in the application of the superposition principle to ship 

 behavior was taken by Gerritsma [7] when he showed that the added resistance, 

 power, torque, or propeller revolutions in waves could also be handled in this 

 way. However, the work of Maruo [8] had indicated that these quantities are 

 roughly proportional to the square of wave amplitude and therefore should not 

 be squared as are motion amplitude operators. The non-dimensional coefficient 

 of power increase, AP, used by Gerritsma was 



AP 



pgf^vBVL 



which is also the response amplitude operator. Swaan has applied the superpo- 

 sition procedure to predicting trends of power and speed in waves [9], using this 

 coefficient and a conventional amplitude or energy spectrum. 



194 



