No recordings of wave conditions have been made. Boat wake loadings are 

 frequent, because boat traffic is heavy, with vessels ranging in size from 

 small pleasure craft to the fishing fleet size, including heavy trawlers, 

 purse seiners, oceangoing cruise ships, ferries, and freighters. 



c. Breakwater Des cription. 



(1) Design. The structure is of the Alaska-catamaran or ladder type, 

 23 feet wide and 6 feet deep, made of posttensioned, foam-filled modules of 

 lightweight reinforced concrete (Fig. 3). The main breakwater is 963 feet 

 long, parallel to the shore (and Tongass Narrows). A separate 120-foot sec- 

 tion was positioned off the end of a rock breakwater forming Bar Harbor No. 2 

 to attenuate waves from the south. The layout is shown in Figure 4. A 165- 

 foot section planned at the northern end was omitted to avoid conflict with a 

 loading pier. Anchor chains at 60-foot intervals connect the breakwater to 

 concrete anchor blocks weighing 18 tons on the inside and 60 tons on the out- 

 side; 100-ton anchors hold the 120-foot section. 



(2) Installat ion. Installation began in October 1979. Storm damage 

 occurred during construction to unassembled units moored at the site. The 

 cost (1980) of the breakwater was $1,400 per foot. Those responsible for the 

 breakwater design, construction, and operation are as follows: 



Owner-Operator: City and Borough of Ketchikan, Alaska 



Designers: U.S. Army Engineer District, Alaska 

 Anchorage, Alaska 



Tryck, Nyman and Hayes 

 Anchorage, Alaska 



Builder: Concrete Technology 

 Tacoraa , Washington 



Installers: Dawson Construction 



Bellingham, Washington 



Smart Crane Company 

 Ketchikan, Alaska 



The following comments on installation were abstracted from an interview 

 with one of the installers of Smart Crane Company (B. Smart): 



The major difficulty experienced was stringing, flushing, greas- 

 ing, and sealing the posttension cables in the stress-strand ducts. 

 Holes between adjacent modules rarely lined up. The general assembly 

 technique was a difficult procedure to carry out in field condi- 

 tions. Larger diameter, lower stressed galvanized rods would have 

 been easier to use. The I-inch cable with threaded studs used to 

 join 240-foot sections was difficult to tighten, since the cable 

 rotated as the nuts were turned. Towing of the 240-foot sections was 

 very difficult except at a very low speed. A skiff was almost as 

 effective as a tug. The accurate placement of the outer row of 

 anchors on a stable site was difficult because of the anchor weights. 



11 



