constructed to allow the marine-related activities in the research programs to 

 be operational year round. 



b. Site Conditions. Tide data are the same as Port of Friday Harbor. 

 The breakwater was designed for a 1.5-knot current. 



The design parameters were 46-knot wind, fetch-limited, significant wave 

 height of 3.0 feet, period of 3.5 seconds, current of 1.5 knots. Boat wakes 

 are common. 



c. Breakwater Description. 



(1) Design and Installation. The breakwater is a reinforced con- 

 crete caisson cast over a polystyrene foam core with a cross section 4.5 by 15 

 feet with an 18-inch freeboard and is L-shaped with two 130-foot sections on 

 the long leg parallel to the shore, and one similar section on the short leg 

 (see Fig. 22). The anchor system is laid out to maintain about a 6-foot space 

 between the sections to avoid linkage problems. Short gangways provide access 

 between units. The breakwaters are used as staging areas to handle nets and 

 other gear, and also to provide a protected mooring area. The surface of the 

 units was left rough for good footing. 



The anchor system consists of two anchor lines of 1-inch stud-link chain 

 at each end of each section, with one line to the outside at 45° to the break- 

 water, and the second at the same angle to the inside. 



The bottom conditions at the site, a shallow covering of rock, led to 

 restraint supplied by attaching clump weights to the anchor lines. These were 

 concrete blocks 4.5 by 4.5 by 3 feet. The main anchors were concrete blocks 8 

 by 8 by 6 feet. 



The breakwater was installed in 1979 at a cost of $790 per foot. Those 

 responsible for the breakwater design and operation are as follows: 



Owner-Operator: University of Washington 

 Oceanographic Laboratory 

 Friday Harbor, Washington 



Designer : ABAM Engineers 



1127 Port of Tacoma Road 

 Tacoma, Washington 



(2) Performance. The users are satisfied with the breakwater per- 

 formance which has made possible the desired year-round operation of the labo- 

 ratory activities. The roughened surface provides good footing, but is hard 

 to clean. An unforeseen benefit from the view of the marine biologist is that 

 the breakwater has attracted marine growths and animals distinctly different 

 from those around the Port of Friday Harbor breakwater, only a few hundred 

 yards distant. 



Some adjustments in the breakwater were necessary after installation. 

 The gangways between the sections had to be redesigned to provide greater 

 freedom of movement to avoid being overstressed. One of the sections did not 



40 



