where H = the significant wave height with an annual probability of 

 exceedance of 0.0000001 computed by the program using F(Hg). The program 

 also requires that a representative repair cost per unit volume of armor layer 

 and the total volume of the armor layer per unit trunk length by input. This 

 allows the expected annual cost of repairs E($D/yr} to be estimated as 



EJMl . vol -^ eM (D6) 



(yr/ vol (yrj 



5. The interval at which a specified level of damage will occur is 

 estimated in two ways. The first simply divides the specified level of per- 

 cent damage by the expected annual amount to give an average repair interval 

 in years. This is considered to be much more appropriate since it includes an 

 account of all the events addressed in the computation of expectation and in- 

 directly measures the real world accumulation of damage from successive 

 storms. The other method involves solving the %D{U^/H^) function for the 

 wave height H^ which would cause the specified level of damage. The speci- 

 fied Extremal Type I F(H ) is then applied to determine the return period 



RT of this Hg as 



f^T(H^) = ,p Jf(h^)j (D7) 



This second method is much less conservative and will predict an interval on 

 the order of A times as long as that predicted by the first method. 

 Program input 



6. Written in FORTRAN IV as implemented on the US Army Engineer Water- 

 ways Experiment Station (WES) Honeywell DPS-8 mainframe system, BWDAMAGE is 

 completely interactive in its present form. A BASIC version written for the 

 IBM PC is also available. 



Sample Interactive Session 



7. The following sample interactive session demonstrates the required 

 and optional user input: 



D3 



