f. Wave Types (Block 25) . Waves are classified into the following four 

 types : 



(1) A spilling breaker occurs when the wave crest becomes 

 unstable at the top and breaks to flow down the front face of the 

 wave producing a foam surface (Fig. 8). 



Figure 8. Spilling breaker. 



(2) A plunging breaker occurs when the wave crest curls over the 

 front face of the wave and falls onto the base to produce a high 

 splash and much foam (Fig. 9). This hollow part under the curled- 

 over crest is sometimes termed the "pipeline." 





Figure 9. Plunging breaker. 



15 



