measuring (Figure 40) the vertical linear distance from the B and C lines to the 

 design H/L^ of interest; denote these values, Aj and A^, respectively. Weighting 

 factors, W, are then established as: 



W, = 



A 



L Ai + Az 



(50) 



W„ = 



U Ai + A2 

 The interpolated F^ value is finally determined as: 



(Fd)d = Wl (Fd)l + Wu (Fd)^j 



where the subscripts, D, L and U outside the parentheses denote: "Design," "Lower" 

 (Case B), and "Upper" (Case C). 



Example 7-a— Numerical Illustration of Interpolation Procedure 



Consider the following wave conditions selected for design 



Hp = 44 ft 

 T = 10 sec 

 hj^ = 160 ft 



which yield 



^"D = 2^ '^' = 512 ft 



^ 

 ^Od 



= 0.313 



'D 



T = 0.0859 



and suppose that we require the maximum dimensionless drag force on a piling that extends 

 from the bottom to above the crest level. This maximum value would occur at6-0° and is 

 the value labeled "SURFACE" in the tabulations. Plotting of the wave steepness and relative 

 depth on Figure 40 indicates that the design values are spanned by Cases 7-B, 7-C, 8-B and 

 8-C. In accordance with the preceding section the values of F^(0°, Surf.) for Cases 6-B, 6-C, 

 7-B, 7-C, 8-B, 8-C, 9-B, and 9-C are required for interpolation and are summarized in 

 Table Q. 



90 



