145. Plunge distance was also plotted as a function of the local surf 

 similarity parameter (Figure 46) . The visual-fit solid line through the data 

 is expressed as 



Xp 



= 0.65£ b 105 + 1.80 



(90) 



5.0 



Xp/Hb 































Barred Profiles 













Plane Slopes 



4.0 



V 



• ' ~~ -. 









3.0 



■ 





■ 



."■ 



■ 



2.0 





1 1 





1 



i i 



0.0 



0.5 



1.0 



1.5 



4 



2.0 



2.5 



3.0 



Figure 46. Xp/H b as a function of £ b 



for 0.31 < £ b < 2.74 , where £ b is an inshore surf similarity parameter. 

 Both Figures 45 and 46 show comparable scatter of the data, and neither 

 Equation 89 nor 90 appears to be a better predictor of plunge distance. 



146. The equations developed in Part II for plunge distance on plane 

 slopes is shown by the dashed line in Figures 45 and 46. Plunge distance for 

 barred profiles are shorter than those for plane slopes with common values of 

 £ . This can be explained by the transformation of breaker type caused by 

 the barred profiles. Spilling and plunging waves would be expected for the 

 range of £ -values shown in Figures 45 and 46, whereas spilling, plunging, 

 and collapsing waves occurred for the barred profiles. The data obtained for 

 barred profiles indicate that Xp/H b decreases steeply for smaller surf 



100 



