PART II: THE MODEL 



Design of the Model 



4. Tests were conducted at an undistorted linear scale of 1:25, model 

 to prototype. Scale selection was based on the size of model armor units 

 available compared to the estimated size of prototype armor units required for 

 stability, capabilities of the available wave generator, and elimination of 

 stability scale effects (Hudson 1975). Based on Froude's Model Law (Stevens 

 et al. 1942) and the linear scale of 1:25, the following model-to-prototype 

 relations were derived. Dimensions are in terms of length (L) and time (T). 







Model-to-Prototype 



Characteristic 



Dimension 



Scale Relation (r) 



Length 



L 



L^ = 1:25 



Area 



L^ 



A = L^ = 1:625 

 r r 



Volume 



l3 



V^ = lJ = 1:15,625 



Time 



T 



T -l''^ -^:5 



5. The specific weight of water used in the model was assumed to be 

 62.4 pcf and that of seawater is 64.0 pcf. Specific weights of the model con- 

 struction materials were not identical to their prototype counterparts. These 

 variables were related using the following transference equation: 



("a) Aa) /L 



\ /m \ /m / 



a"H^ 



(S, 



- 1 



5). 



- 1 



(1) 



where 



m and p = model and prototype quantities, respectively 

 W = weight of an individual armor unit, lb 



Y = specific weight of an individual armor unit, pcf 



Lm/Lp 



linear scale of the model 



S_ = specific gravity of an individual armor unit relative to the 

 water in which it was placed, i.e., S^ = Y„/y„ , 



where y is the specific weight of water, pcf. 



