io 



Effect of Shoaling ; An additional item included in the table is the 

 ratio of wave height in shallow water to its deep water wave height when 

 unaffected by refraction „# This is equal to 



H/H ' =/l o 1 o ~ 



^2 n C7C^ (21) 



Hyperbolic Functions of d/L ; In addition to the above functions, 

 values of sinh 2 it d/L, cosh 2 7rd/L, sinh 47rd/L and cosh 4- TT d/L have been 

 put in the tables as well as 2 TT d/L and 4 IT d/L° These have been put in 

 as functions of d/Lo, that is, for a given d/L,-, the values of sinh 2 TT d/L 

 and etc are given. 



Accuracy of Computations ; The values were arrived at using five place 

 figures and then after all of the work was completed, the last place was 

 dropped with the corresponding change of one figure up or down in the fourth 

 place . Because the basic interpolation was done with graphs, errors of 

 one in the fourth significant figure may exist. Because of this, and 

 because the square of the hyperbolic tangent is used to find the energy 

 coefficient, only three places were reported for a certain range as it was 

 felt that the additional figure could not be justified,, Actually, in 

 practice, it has been found that usually three figures are the greatest 

 accuracy to which measurements can be made. However, when dealing with 

 differences, this last place is needed to give the desired results. 



It must be remembered that occasionally an accumulation must be added 

 to one of the values of d/L. Thus in 4 TT d/L the accumulation is in- 

 creased by the factor of 47Tand so the first differences between values of 

 the sinh and cosh of 4 rr d/L will jump. However, the corresponding values 

 of n were plotted on an extended series of graphs and a curve drawn through 

 them and then the correct values read off and placed in the table. Thus 



the true values of n vs d/L are in the tables. 



' o 



It is to be noted that for the convenience of the user the summary of 

 the various data is presented in two tables. Table 1 shows the various 

 terms for even values of d/L , and Table II shows the same terms for even 

 values of d/L over the range°where interpolation in Table I is inconvenient ■ 



Breakers and Surf, Principles of Forecasting, Hydrographic Office 

 Publication No. 234, 



