(3) Per formance . The users are satisfied with protection afforded 

 by the breakwater. Mooring lines and dispositions are adapted to accept the 

 swell and boat wake that enter the harbor. 



No underwater components of the breakwater have been checked. The only 

 maintenance problem has been repairing and replacing worn chain links con- 

 necting the modules; several rubber bumpers, part of the connecting systems 

 between modules, have disappeared (Fig. 9). There is some correlation between 

 missing bumpers and worn chain links. Although the breakwater is not consid- 

 ered the responsibiity of the harbormaster, he has been welding worn connect- 

 ing links and checking for other stress points. 



Lightweight concrete was used in forming the breakwater modules. There 

 are several spall areas that have been attributed to banging of corners, etc., 

 during transport and construction. Some of these were successfully patched 

 with epoxy shortly after construction. Some of the reinforcement is exposed 

 and rusty, but spalling is slow, if at all. 



Because of the shortage of mooring spaces, large trawlers tie up to both 

 sides of the breakwater, and may be the cause of the nonlinear breakwater 

 alineraent observed. The mass per foot of the trawlers may exceed that of the 

 breakwater. A differential draft has developed on some sections, with 14 

 inches of freeboard on one side of a pontoon and only 12 inches on the other 

 side. No explanation is offered. Marine growth at Sitka is not as active as 

 at Ketchikan. 



d. Discussion . The breakwater has performed satisfactorily during its 

 7-year life. Although the swell transmitted into the harbor has been a nui- 

 sance, the users have adapted. Maintenance problems have been minor, mostly 

 involving replacing worn chain links. Underwater components should be inspec- 

 ted. The present 3-link chain-rubber bumper module connections should be 

 replaced with a newer, improved design such as that employed in the revisions 

 at the Tenakee Springs breakwater, discussed in the following section. Tran- 

 sient boats usually tie up at a floating breakwater, whether or not such use 

 is authorized. Designs should recognize this pattern or operations personnel 

 should be given time and authority to restrict tie-ups. 



3. Tenakee Springs , Alaska . 



a. Location. Tenakee Springs, Alaska (Fig. 10), is a small village about 

 60 miles southwest of Juneau, Alaska, with about 80 permanent residents who 

 are income-dependent upon fishing, crabbing (cannery recently closed), log- 

 ging, retirement incomes, and limited tourism. 



b. Site Conditions . A small natural harbor is unprotected from the 

 west with a fetch of about 5 miles out of Crab Bay around to the southeast 

 where the fetch is about 3 miles from Corner Bay. Storms from these direc- 

 tions are common winter occurrences. There are no wind records for the site, 

 but according to local residents, speeds ranging from 60 to 70 miles per hour 

 have occurred. 



Tide data include a maximum range from -5 to +20 feet MLLW. Tidal cur- 

 rents are less than 1 knot at the breakwater site. Bottom elevations are as 

 follows: 



23 



