Computations 



6. The sequence of computations is summarized in the BWCOMP flowchart 

 in Figure B1. The narrative below describes the assumptions and equations 

 applied in this sequence. 



7. The program performs all computations for each of seven pairs 

 of seaward and leeward slopes: 1:1.5/1:1.5, 1:2.0/1:1.5, 1:2.0/1:2.0, 

 1:2.5/1:1.5, 1:2.5/1:2.0, 1:3.0/1:1.5, and 1:3.0/1:2.0. Identical computa- 

 tions are performed for each of 10 armor units for each of these slope com- 

 binations. The stability, geometry, and runup coefficients which are assumed 

 for each armor unit are specified in DATA statements at the beginning of the 

 program listing, as summarized in Table B1. The crest elevation is first as- 

 sumed as 0.3 m then increased in 0.3-m increments until the estimated trans- 

 mitted wave height is less than the specified maximum. The computed dimen- 

 sions and costs for all 10 armor units are then printed in a table for each 

 slope combination (i.e. in seven tables). 



8. The wave conditions are checked for breaking or nonbreaking condi- 

 tions by Goda's breaker index formula (Goda 1975) assuming a horizontal bot- 

 tom. The stability or transmission incident heights are set equal to the 

 breaker height at the specified depth if the breaker height is smaller. The 

 stability coefficient K. for Hudson's formula (Equation 1 in the main text) 

 is chosen accordingly for each armor unit type. The weight computed by Hud- 

 son's formula is then applied to compute the armor thickness and minimum crest 

 width by Equation 9 (main text) by assuming "n" values of 2 and 3, respec- 

 tively. The crest elevation derived from wave transmission computations then 

 allows all dimensions of the parameterized cross section (Figure 17, main 

 text) and the corresponding volumes and costs per unit trunk length to be 

 estimated. Specifications from Figures 7-109 through 7-115 in the SPM (1984) 

 are applied to estimate the armor thickness and number of individual armor 

 units per unit trunk length. 



9. The crest elevation is determined by first assuming a crest eleva- 

 tion (initially 1 ft* above the still-water level) and then estimating the 



x^ transmitted wave for the specified incident wave condition and the current 

 breakwater geometry. The estimated transmitted wave height is compared to the 



* To convert feet to metres, use a conversion factor of 0.3048. 



B3 



