aw 
5 
i 
Refraction coefficient of the breakwater's depth d 
inal 
tl} 
Wave length at the breakwater's position 
Lo = Deep water wave length 
Sp = Specific gravity of the fluid in which the breakwater rests 
Sy = Specific gravity of the breakwater rock 
Yy = Unit weight of fresh water 
W = Stone weight 
General Equations 
In the article, "A Formula for the Calculation of Rock Fill Dikes," (1) 
Iribarren presented formulae for the design of rubble mound structures. These 
formulae permitted calculation of sea-side slopes and weight of individual 
stones above the water surface. His result for the calculation of the weight 
of cap rock, in wide use for many years, is 
WKS 
W = = (1) 
(cos & - sin & 3 (S, - 1)? 
where 
Sp = specific gravity of the rock 
e = the angle the sea-slopes makes with the horizontal 
(A slope is usually referred to as l/cot. ) 
H = wave height (in feet) 
W = weight of stone (in tons) 
_K = an empirically determined coefficient for all unevaluated 
variables 
4.68 x 1074 for natural rubble 
5.93 x 1074 for artificial blocks 
This equation however, is not dimensionally homogeneous and has been modified 
by Hudson (3 » using the same assumptions and force diagram as Iribarren 
ale 
