the full range of tides and thereby to reduce the horizontal excursions of the 

 breakwater, particularly at lower tide elevations. Initial anchor line ten- 

 sions were 5,000 ± 1,000 lb. Four months prior to the termination of the 

 field test, the clump weights were removed. During this 4-month period, the 

 effects of this clump weight removal on float motions, anchor forces, and wave 

 attenuation were monitored. 



The pipe-tire breakwater was anchored alongside the concrete breakwater 

 (Photograph 15) with ten 20-ft-long steel H-piles (HP 12 by 53). Anchor lines, 

 which consisted of 1-1/4- in. -diameter, three-strand, nylon rope with 10 ft of 

 3/4-in. stud link chain at each end, were attached to both ends of each pipe. 

 Minimum slope for these anchor lines was about 1 vertical to 4 horizontal. The 

 center and end H-piles had one anchor line each, while the remaining four 

 anchor piles were attached to three anchor lines apiece. The four end pilings 

 were offset at an outward angle to counteract the opposing longitudinal com- 

 ponent of force from the adjacent anchor lines. 



TEST CONDITIONS 



The prototype breakwater test site at West Point was selected for its ex- 

 posed location. This choice proved to be more than adequate for providing the 

 desired wave conditions. During the 16-month test period more than 20 storms 

 moved through Puget Sound. One storm brought winds in excess of 60 knots and 

 generated waves over 4 ft high. But most often storm winds were in the 20- to 

 40-knot range with wave heights between 2 and 3.5 ft (Photograph 16). Access 

 to the breakwater was difficult when winds exceeded 10 knots; 15- knot winds 

 made working conditions potentially hazardous. 



Advantage was taken of calm periods to make repairs and to conduct addi- 

 tional tests. Four boat wake tests and an anchor line stiffness (pull) test 

 were conducted at various points in the program. For two of the boat wake 

 tests, 41- ft Coast Guard cutters were used to generate waves (Photograph 17). 

 The other two tests used large (75-ft and 110-ft) tugboats. Boat-generated 

 waves were in the 2- to 3-ft range. For the anchor stiffness test, a 4,000-hp 

 tugboat was used to pull on the breakwater with varying loads, while surveying 

 instruments measured displacements, and load cells in the anchor lines moni- 

 tored anchor forces (Photograph 18). This test was conducted to obtain simul- 

 taneous measurements of breakwater lateral displacement and the resisting 



115 



