The depth of breaker, d^, is determined from Diagram D for the forecast 

 period, T, and the breaker height, H b , obtained from Diagram C„ 



Breaker Angle 



The angle with which the breakers make with the bottom contours is 

 obtained from the same data used in preparing Diagram B» Referring to 

 Table I s it is noted that breaker angle, ocb , and deep water wave direction 

 <x , will give a family of curves of constant Hq/t^o Such a plot is 

 shown in Diagram E, Figure 2„ As in the case of Diagram B, the scale of 

 <Xp may be replaced by true azimuth when a particular beach is under con- 

 sideration o Thus, in Figure 1 for Las Pulgas Beach, the true azimuth and 

 compass points are shown instead of the deep water angle, cc Q „ 



Distance to Breaker from Edge of Still Water 



The distance Xfc from the edge of still water to the point of break- 

 ing is a function of the bottom profile and the stage of the tide„ A 

 simple diagram to give this distance would be merely a bottom profile with 

 various stages of the tide indicated as shown in the following sketch,. 



With the stage of tide known and the depth at breaking determined from 

 Diagram D, the point at breaking can be located„ The distance from this 

 point to the edge of still water is scaled from the sketch „ Because such a 

 diagram requires a sliding scale, a family of profile curves is used to 

 simplify the procedure „ The intersections between the water surface (at 

 various stages of the tide) and the bottom are determined, and the profiles 

 below these points then are plotted with the above mentioned intersections 

 at a common point,, Diagram F (Figure 1) shows such a diagram for' Las 

 Pulgas Beacho It is to be noted that Diagrams A-E, inclusive, are general 

 in character and apply to any straight beach with proper notation as to the 

 oc scales in Diagrams B and E| however, Diagram F is different for each 

 locality and therefore is omitted from the general diagrams. Figure 2„ 



When available it is also planned to include a diagram for forecasting 

 the strength of the littoral current „ 



28 



