periods of slack water, occasional large swells from the southeast, and occa- 

 sional heavy wash from shipping operations. Testing was conducted at slack 

 water to minimize undesirable effects. 



The design at Stokes Bay consisted of equally spaced crossmembers connect- 

 ing the front and back booms (leading and trailing edge) (Fig. 181). This 

 produced a rectangular floating plate on the surface with slots of open water 

 between the crossmembers. These slots generate turbulence which helps dissi- 

 pate a large part of the wave energy. The model was composed essentially of 

 five units, each 9.6 by 10 meters (31 by 33 feet), joined by two 10- by 10- 

 inch steel sections along the entire length of the front and back booms; the 

 overall dimensions were 48 by 10 meters (157 by 33 feet). This form of 

 construction greatly reduced launching problems because the breakwater was 

 constructed in sections and assembled together while afloat. The marine 

 plywood model was 0.3 meter (1 foot) in overall depth and floated with about 

 0.045 meter (0.15 foot) freeboard, this value being controlled by buoyancy 

 compartments throughout the complete structure. In the mooring arrangement 

 (Fig. 182), nylon lines, each attached to 50 feet of 3/4-inch chain with a 

 plow anchor on the end, were fastened to each corner of the breakwater. Nylon 

 was used to eliminate shock loads on the breakwater from movement in the 

 seaway. 



Figure 181. Scale model of Harris floating breakwater at Stokes Bay, England 

 (after Harris and Thomas, 1974). 



242 



