Wove Period For 60-ft Depth (s) 



'•" p — r 



iij 



total bag width 



(D CD 



O H/l. = 



1.(11 hi i 



<D H.i. = 



1 ill ..i i 



® II. 1. =■ 



I.D5 hi i 



© H/l. = 



I.(l7..r 1 



• H/l. = 



III'/ in 1 



Ratio of Wavelength-to-Water Depth, L/d 



Figure 178. Effect of relative water depth, L/d, and incident wave steep- 

 ness, H/L, on transmission coefficients, C t , for flat, water- 

 filled bag floating breakwater (after Jones, 1974). 



XI. TURBULENCE-GENERATOR FLOATING BREAKWATERS 



A floating breakwater concept of relatively thin, horizontal barriers, 

 developed and tested in both laboratory and field conditions, causes dissipa- 

 tion of wave energy without creating major stresses in the structure and 

 moorings. The dissipative mechanism for this design arises as the greater 

 part of the wave breaks over the upper surface of the system with great tur- 

 bulence and energy loss taking place as the fluid interacts with the structure 

 members. Major eddy formations exist as the fluid moves between and around 

 the breakwater elements with supplementary loss of energy, and the inertia of 

 the breakwater itself opposes the orbital motion reflecting a small part of 

 the wave energy. The advantages of this design include shallow draft, rela- 

 tively lightweight, and modest mooring loads, even in fairly strong currents. 



1. Seabreaker Floating Breakwater . 



Hasler (1974) developed the floating breakwater concept known as the 

 "Seabreaker," which uses a long, stiff, horizontal surface for wave attenua- 

 tion. This design evolved during flume tests in England in 1963. Further 

 tank tests and model experiments in simulated prototype waves led to the con- 

 struction in 1971 of a long, rigid pontoon of specialized design (Fig. 179), 

 131 feet long, full size, with a universal joint at either end for joining a 

 string of units. 



239 



