Chapter 6 

 BREAKERS AND SURF; THEIR IMPORTANCE AND ORIGIN 



When waves break, whether as a result of advancing into shoaling 

 water or of dashing against ledges or breakwaters, they are known as 

 "breakers," to distinguish them from the storm waves that break out 

 at sea. "Surf" is the name commonly applied to the composite phe- 

 nomenon when breakers develop in a more or less continuous belt 

 along the shore, or over some submerged bank or reef. 



Any type of wave that moves shoreward, or even parallel with the 

 shore line, may produce a surf; whether it will actually do so, in any 

 given case, depends on various factors to be discussed below. In 

 considering surf, it is therefore necessary to include storm waves that 

 may be generated by high winds blowing at the time and place, and 

 also swells that may have come from a long distance, for it is not 

 unusual to encounter a heavy surf in calm weather as well as in 

 stormy. 



An observer standing on the shore is in an excellent position to 

 judge the state of the breakers, and most of the published discussions 

 of surf have been from the standpoint of the landsman in relation 

 to engineering problems, such as the construction of breakwaters and 

 sea walls, for example, or in relation to the erosion of coast lines. In 

 the following account we attempt to present the matter from the 

 standpoint of the man at sea, who may have occasion to bring landing 

 craft in to the beach through the surf, or out again through it. 



THE IMPORTANCE OF SURF 



Breakers, when seen from the seaward, never seem as dangerous as 

 they really are, because a view of their backs gives a very inadequate 

 idea of their heights or steepness ; what appears to be a mere swash on 

 the beach, when seen from offshore, may actually be a very dangerous 

 surf indeed. (This point is emphasized in Knight's Modern Seaman- 

 ship, 31 a book with which every ship's officer ought to be familiar.) 

 A heavy surf also carries an enormous power of destruction; any sea- 

 man knows that no one can hold his footing on the deck if it be swept 

 by heavy breakers. 



A general knowledge of the characteristics of surf, and especially 

 an ability to forecast its height, is therefore of great importance in 



31 Kni£ht, A. M. 1945. Modern Seamanship. 11th ed. New York. p. 388. 



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