FLOATING BREAKWATER FIELD EXPERIENCE, WEST COAST 



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Eugene P. Riahey 



I. INTRODUCTION 



The increased demand by the boating public and industry for more moorage 

 facilities challenges the planners and designers of small-craft harbors to 

 explore all alternatives in developing harbors that have adequate protection 

 from wind waves and boat wakes . Most of the natural harbors developed near 

 population centers, where boating demands are greatest, are overcrowded. 

 Floating breakwaters have become an alternative with an active potential in 

 future harbor-marina design. The floating breakwater has been adopted at a 

 number of sites where water depth or other constraints render a fixed struc- 

 ture too costly, and is proposed for countless others. Although there are 

 other uses for floating breakwaters, such as in waterfront construction and 

 operation, log rafting in the timber harvesting industry, beach erosion con- 

 trol, etc., the most prominent applications relate to the small-craft harbor 

 or marina. 



On location, the floating breakwater is subject to random wave loadings 

 which can induce motions with components in all directions. The intended job 

 of the breakwater is to reduce the incident wave system to an acceptable 

 level. The transmission characteristics of this reduction capability are 

 very sensitive to the period (or length) of the incident wave field. Numerous 

 reports on model tests of transmission characteristics are available, but 

 reports on actual field experiences with floating breakwaters are few. 

 Although several floating breakwaters have been in use for as long as 

 8 years, there has been little information exchanged as to the type of break- 

 water, the anchorages, and the connections between units. These are con- 

 sidered major points of interest in improving the design of floating break- 

 waters. 



To cover these points, the following questions were established as a 

 checklist for evaluating field experience with construction and subsequent 

 performance of floating breakwaters: 



(1) What were the site conditions and why was the floating 

 breakwater chosen? 



(2) How was it deployed? 



(3) Were there any unusual installation problems? 



(4) What anchoring and connector systems were used? 



(5) Have there been any fouling, corrosion, or fatiguing prob- 

 lems? 



(6) What maintenance has been carried out? 



(7) Have any environmental problems (shoreline changes, icing, 

 stability) been encountered? 



